first configure+compile version

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/trunk-md@1804123 13f79535-47bb-0310-9956-ffa450edef68

41 files changed, 12861 insertions, 70 deletions

diff --git a/modules/http2/h2_util.c b/modules/http2/h2_util.c
index e1879cb200..47dcdf56b2 100644
--- a/modules/http2/h2_util.c
+++ b/modules/http2/h2_util.c
@@ -112,6 +112,8 @@ void h2_util_camel_case_header(char *s, size_t len)
     }
 }
 
+/* base64 url encoding ****************************************************************************/
+
 static const int BASE64URL_UINT6[] = {
 /*   0   1   2   3   4   5   6   7   8   9   a   b   c   d   e   f        */
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  0 */
@@ -174,6 +176,7 @@ apr_size_t h2_util_base64url_decode(const char **decoded, const char *encoded,
             n = ((BASE64URL_UINT6[ e[mlen+0] ] << 18) +
                  (BASE64URL_UINT6[ e[mlen+1] ] << 12));
             *d++ = n >> 16;
+            remain = 1;
             break;
         case 3:
             n = ((BASE64URL_UINT6[ e[mlen+0] ] << 18) +
@@ -181,6 +184,7 @@ apr_size_t h2_util_base64url_decode(const char **decoded, const char *encoded,
                  (BASE64URL_UINT6[ e[mlen+2] ] << 6));
             *d++ = n >> 16;
             *d++ = n >> 8 & 0xffu;
+            remain = 2;
             break;
         default: /* do nothing */
             break;
@@ -189,78 +193,35 @@ apr_size_t h2_util_base64url_decode(const char **decoded, const char *encoded,
 }
 
 const char *h2_util_base64url_encode(const char *data, 
-                                     apr_size_t len, apr_pool_t *pool)
+                                     apr_size_t dlen, apr_pool_t *pool)
 {
-    apr_size_t mlen = ((len+2)/3)*3;
-    apr_size_t slen = (mlen/3)*4;
-    apr_size_t i;
+    long i, len = (int)dlen;
+    apr_size_t slen = ((dlen+2)/3)*4 + 1; /* 0 terminated */
     const unsigned char *udata = (const unsigned char*)data;
-    char *enc, *p = apr_pcalloc(pool, slen+1); /* 0 terminated */
+    char *enc, *p = apr_pcalloc(pool, slen);
     
     enc = p;
-    for (i = 0; i < mlen; i+= 3) {
+    for (i = 0; i < len-2; i+= 3) {
         *p++ = BASE64URL_CHARS[ (udata[i] >> 2) & 0x3fu ];
-        *p++ = BASE64URL_CHARS[ ((udata[i] << 4) + 
-                                 ((i+1 < len)? (udata[i+1] >> 4) : 0)) & 0x3fu ];
-        *p++ = BASE64URL_CHARS[ ((udata[i+1] << 2) + 
-                                 ((i+2 < len)? (udata[i+2] >> 6) : 0)) & 0x3fu ];
-        if (i+2 < len) {
-            *p++ = BASE64URL_CHARS[ udata[i+2] & 0x3fu ];
-        }
+        *p++ = BASE64URL_CHARS[ ((udata[i] << 4) + (udata[i+1] >> 4)) & 0x3fu ];
+        *p++ = BASE64URL_CHARS[ ((udata[i+1] << 2) + (udata[i+2] >> 6)) & 0x3fu ];
+        *p++ = BASE64URL_CHARS[ udata[i+2] & 0x3fu ];
     }
     
-    return enc;
-}
-
-int h2_util_contains_token(apr_pool_t *pool, const char *s, const char *token)
-{
-    char *c;
-    if (s) {
-        if (!apr_strnatcasecmp(s, token)) {   /* the simple life */
-            return 1;
-        }
-        
-        for (c = ap_get_token(pool, &s, 0); c && *c;
-             c = *s? ap_get_token(pool, &s, 0) : NULL) {
-            if (!apr_strnatcasecmp(c, token)) { /* seeing the token? */
-                return 1;
-            }
-            while (*s++ == ';') {            /* skip parameters */
-                ap_get_token(pool, &s, 0);
-            }
-            if (*s++ != ',') {               /* need comma separation */
-                return 0;
-            }
+    if (i < len) {
+        *p++ = BASE64URL_CHARS[ (udata[i] >> 2) & 0x3fu ];
+        if (i == (len - 1)) {
+            *p++ = BASE64URL_CHARS[ (udata[i] << 4) & 0x3fu ];
         }
-    }
-    return 0;
-}
-
-const char *h2_util_first_token_match(apr_pool_t *pool, const char *s, 
-                                      const char *tokens[], apr_size_t len)
-{
-    char *c;
-    apr_size_t i;
-    if (s && *s) {
-        for (c = ap_get_token(pool, &s, 0); c && *c;
-             c = *s? ap_get_token(pool, &s, 0) : NULL) {
-            for (i = 0; i < len; ++i) {
-                if (!apr_strnatcasecmp(c, tokens[i])) {
-                    return tokens[i];
-                }
-            }
-            while (*s++ == ';') {            /* skip parameters */
-                ap_get_token(pool, &s, 0);
-            }
-            if (*s++ != ',') {               /* need comma separation */
-                return 0;
-            }
+        else {
+            *p++ = BASE64URL_CHARS[ ((udata[i] << 4) + (udata[i+1] >> 4)) & 0x3fu ];
+            *p++ = BASE64URL_CHARS[ (udata[i+1] << 2) & 0x3fu ];
         }
     }
-    return NULL;
+    *p++ = '\0';
+    return enc;
 }
 
-
 /*******************************************************************************
  * ihash - hash for structs with int identifier
  ******************************************************************************/
diff --git a/modules/http2/h2_util.h b/modules/http2/h2_util.h
index b2c25f69cc..01ccccd765 100644
--- a/modules/http2/h2_util.h
+++ b/modules/http2/h2_util.h
@@ -337,15 +337,6 @@ unsigned char h2_log2(int n);
  */
 apr_size_t h2_util_table_bytes(apr_table_t *t, apr_size_t pair_extra);
 
-/**
- * Return != 0 iff the string s contains the token, as specified in
- * HTTP header syntax, rfc7230.
- */
-int h2_util_contains_token(apr_pool_t *pool, const char *s, const char *token);
-
-const char *h2_util_first_token_match(apr_pool_t *pool, const char *s, 
-                                      const char *tokens[], apr_size_t len);
-
 /** Match a header value against a string constance, case insensitive */
 #define H2_HD_MATCH_LIT(l, name, nlen)  \
     ((nlen == sizeof(l) - 1) && !apr_strnatcasecmp(l, name))
diff --git a/modules/http2/h2_version.h b/modules/http2/h2_version.h
index ac029bbe6b..50e9abc03f 100644
--- a/modules/http2/h2_version.h
+++ b/modules/http2/h2_version.h
@@ -26,7 +26,7 @@
  * @macro
  * Version number of the http2 module as c string
  */
-#define MOD_HTTP2_VERSION "1.10.10-DEV"
+#define MOD_HTTP2_VERSION "1.10.11-DEV"
 
 /**
  * @macro
diff --git a/modules/md/Makefile.in b/modules/md/Makefile.in
new file mode 100644
index 0000000000..4395bc3ac7
--- /dev/null
+++ b/modules/md/Makefile.in
@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+#
+#   standard stuff
+#
+
+include $(top_srcdir)/build/special.mk
diff --git a/modules/md/config2.m4 b/modules/md/config2.m4
new file mode 100644
index 0000000000..62b809fd6e
--- /dev/null
+++ b/modules/md/config2.m4
@@ -0,0 +1,296 @@
+dnl Licensed to the Apache Software Foundation (ASF) under one or more
+dnl contributor license agreements.  See the NOTICE file distributed with
+dnl this work for additional information regarding copyright ownership.
+dnl The ASF licenses this file to You under the Apache License, Version 2.0
+dnl (the "License"); you may not use this file except in compliance with
+dnl the License.  You may obtain a copy of the License at
+dnl
+dnl      http://www.apache.org/licenses/LICENSE-2.0
+dnl
+dnl Unless required by applicable law or agreed to in writing, software
+dnl distributed under the License is distributed on an "AS IS" BASIS,
+dnl WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+dnl See the License for the specific language governing permissions and
+dnl limitations under the License.
+
+dnl
+dnl APACHE_CHECK_CURL
+dnl
+dnl Configure for libcurl, giving preference to
+dnl "--with-curl=<path>" if it was specified.
+dnl
+AC_DEFUN([APACHE_CHECK_CURL],[
+  AC_CACHE_CHECK([for curl], [ac_cv_curl], [
+    dnl initialise the variables we use
+    ac_cv_curl=no
+    ap_curl_found=""
+    ap_curl_base=""
+    ap_curl_libs=""
+
+    dnl Determine the curl base directory, if any
+    AC_MSG_CHECKING([for user-provided curl base directory])
+    AC_ARG_WITH(curl, APACHE_HELP_STRING(--with-curl=PATH, curl installation directory), [
+      dnl If --with-curl specifies a directory, we use that directory
+      if test "x$withval" != "xyes" -a "x$withval" != "x"; then
+        dnl This ensures $withval is actually a directory and that it is absolute
+        ap_curl_base="`cd $withval ; pwd`"
+      fi
+    ])
+    if test "x$ap_curl_base" = "x"; then
+      AC_MSG_RESULT(none)
+    else
+      AC_MSG_RESULT($ap_curl_base)
+    fi
+
+    dnl Run header and version checks
+    saved_CPPFLAGS="$CPPFLAGS"
+    saved_LIBS="$LIBS"
+    saved_LDFLAGS="$LDFLAGS"
+
+    dnl Before doing anything else, load in pkg-config variables
+    if test -n "$PKGCONFIG"; then
+      saved_PKG_CONFIG_PATH="$PKG_CONFIG_PATH"
+      AC_MSG_CHECKING([for pkg-config along $PKG_CONFIG_PATH])
+      if test "x$ap_curl_base" != "x" ; then
+        if test -f "${ap_curl_base}/lib/pkgconfig/libcurl.pc"; then
+          dnl Ensure that the given path is used by pkg-config too, otherwise
+          dnl the system libcurl.pc might be picked up instead.
+          PKG_CONFIG_PATH="${ap_curl_base}/lib/pkgconfig${PKG_CONFIG_PATH+:}${PKG_CONFIG_PATH}"
+          export PKG_CONFIG_PATH
+        elif test -f "${ap_curl_base}/lib64/pkgconfig/libcurl.pc"; then
+          dnl Ensure that the given path is used by pkg-config too, otherwise
+          dnl the system libcurl.pc might be picked up instead.
+          PKG_CONFIG_PATH="${ap_curl_base}/lib64/pkgconfig${PKG_CONFIG_PATH+:}${PKG_CONFIG_PATH}"
+          export PKG_CONFIG_PATH
+        fi
+      fi
+      AC_ARG_ENABLE(curl-staticlib-deps,APACHE_HELP_STRING(--enable-curl-staticlib-deps,[link mod_md with dependencies of libcurl's static libraries (as indicated by "pkg-config --static"). Must be specified in addition to --enable-md.]), [
+        if test "$enableval" = "yes"; then
+          PKGCONFIG_LIBOPTS="--static"
+        fi
+      ])
+      ap_curl_libs="`$PKGCONFIG $PKGCONFIG_LIBOPTS --libs-only-l --silence-errors libcurl`"
+      if test $? -eq 0; then
+        ap_curl_found="yes"
+        pkglookup="`$PKGCONFIG --cflags-only-I libcurl`"
+        APR_ADDTO(CPPFLAGS, [$pkglookup])
+        APR_ADDTO(MOD_CFLAGS, [$pkglookup])
+        pkglookup="`$PKGCONFIG $PKGCONFIG_LIBOPTS --libs-only-L libcurl`"
+        APR_ADDTO(LDFLAGS, [$pkglookup])
+        APR_ADDTO(MOD_LDFLAGS, [$pkglookup])
+        pkglookup="`$PKGCONFIG $PKGCONFIG_LIBOPTS --libs-only-other libcurl`"
+        APR_ADDTO(LDFLAGS, [$pkglookup])
+        APR_ADDTO(MOD_LDFLAGS, [$pkglookup])
+      fi
+      PKG_CONFIG_PATH="$saved_PKG_CONFIG_PATH"
+    fi
+
+    dnl fall back to the user-supplied directory if not found via pkg-config
+    if test "x$ap_curl_base" != "x" -a "x$ap_curl_found" = "x"; then
+      APR_ADDTO(CPPFLAGS, [-I$ap_curl_base/include])
+      APR_ADDTO(MOD_CFLAGS, [-I$ap_curl_base/include])
+      APR_ADDTO(LDFLAGS, [-L$ap_curl_base/lib])
+      APR_ADDTO(MOD_LDFLAGS, [-L$ap_curl_base/lib])
+      if test "x$ap_platform_runtime_link_flag" != "x"; then
+        APR_ADDTO(LDFLAGS, [$ap_platform_runtime_link_flag$ap_curl_base/lib])
+        APR_ADDTO(MOD_LDFLAGS, [$ap_platform_runtime_link_flag$ap_curl_base/lib])
+      fi
+    fi
+
+    AC_CHECK_HEADERS([curl/curl.h])
+
+    AC_MSG_CHECKING([for curl version >= 7.50])
+    AC_TRY_COMPILE([#include <curl/curlver.h>],[
+#if !defined(LIBCURL_VERSION_MAJOR)
+#error "Missing libcurl version"
+#endif
+#if LIBCURL_VERSION_MAJOR < 7
+#error "Unsupported libcurl version " LIBCURL_VERSION
+#endif
+#if LIBCURL_VERSION_MAJOR == 7 && LIBCURL_VERSION_MINOR < 50
+#error "Unsupported libcurl version " LIBCURL_VERSION
+#endif],
+      [AC_MSG_RESULT(OK)
+       ac_cv_curl=yes],
+      [AC_MSG_RESULT(FAILED)])
+
+    if test "x$ac_cv_curl" = "xyes"; then
+      ap_curl_libs="${ap_curl_libs:--lcurl} `$apr_config --libs`"
+      APR_ADDTO(MOD_LDFLAGS, [$ap_curl_libs])
+      APR_ADDTO(LIBS, [$ap_curl_libs])
+    fi
+
+    dnl restore
+    CPPFLAGS="$saved_CPPFLAGS"
+    LIBS="$saved_LIBS"
+    LDFLAGS="$saved_LDFLAGS"
+  ])
+  if test "x$ac_cv_curl" = "xyes"; then
+    AC_DEFINE(HAVE_CURL, 1, [Define if curl is available])
+  fi
+])
+
+
+dnl
+dnl APACHE_CHECK_JANSSON
+dnl
+dnl Configure for libjansson, giving preference to
+dnl "--with-jansson=<path>" if it was specified.
+dnl
+AC_DEFUN([APACHE_CHECK_JANSSON],[
+  AC_CACHE_CHECK([for jansson], [ac_cv_jansson], [
+    dnl initialise the variables we use
+    ac_cv_jansson=no
+    ap_jansson_found=""
+    ap_jansson_base=""
+    ap_jansson_libs=""
+
+    dnl Determine the jansson base directory, if any
+    AC_MSG_CHECKING([for user-provided jansson base directory])
+    AC_ARG_WITH(jansson, APACHE_HELP_STRING(--with-jansson=PATH, jansson installation directory), [
+      dnl If --with-jansson specifies a directory, we use that directory
+      if test "x$withval" != "xyes" -a "x$withval" != "x"; then
+        dnl This ensures $withval is actually a directory and that it is absolute
+        ap_jansson_base="`cd $withval ; pwd`"
+      fi
+    ])
+    if test "x$ap_jansson_base" = "x"; then
+      AC_MSG_RESULT(none)
+    else
+      AC_MSG_RESULT($ap_jansson_base)
+    fi
+
+    dnl Run header and version checks
+    saved_CPPFLAGS="$CPPFLAGS"
+    saved_LIBS="$LIBS"
+    saved_LDFLAGS="$LDFLAGS"
+
+    dnl Before doing anything else, load in pkg-config variables
+    if test -n "$PKGCONFIG"; then
+      saved_PKG_CONFIG_PATH="$PKG_CONFIG_PATH"
+      AC_MSG_CHECKING([for pkg-config along $PKG_CONFIG_PATH])
+      if test "x$ap_jansson_base" != "x" ; then
+        if test -f "${ap_jansson_base}/lib/pkgconfig/libjansson.pc"; then
+          dnl Ensure that the given path is used by pkg-config too, otherwise
+          dnl the system libjansson.pc might be picked up instead.
+          PKG_CONFIG_PATH="${ap_jansson_base}/lib/pkgconfig${PKG_CONFIG_PATH+:}${PKG_CONFIG_PATH}"
+          export PKG_CONFIG_PATH
+        elif test -f "${ap_jansson_base}/lib64/pkgconfig/libjansson.pc"; then
+          dnl Ensure that the given path is used by pkg-config too, otherwise
+          dnl the system libjansson.pc might be picked up instead.
+          PKG_CONFIG_PATH="${ap_jansson_base}/lib64/pkgconfig${PKG_CONFIG_PATH+:}${PKG_CONFIG_PATH}"
+          export PKG_CONFIG_PATH
+        fi
+      fi
+      AC_ARG_ENABLE(jansson-staticlib-deps,APACHE_HELP_STRING(--enable-jansson-staticlib-deps,[link mod_md with dependencies of libjansson's static libraries (as indicated by "pkg-config --static"). Must be specified in addition to --enable-md.]), [
+        if test "$enableval" = "yes"; then
+          PKGCONFIG_LIBOPTS="--static"
+        fi
+      ])
+      ap_jansson_libs="`$PKGCONFIG $PKGCONFIG_LIBOPTS --libs-only-l --silence-errors libjansson`"
+      if test $? -eq 0; then
+        ap_jansson_found="yes"
+        pkglookup="`$PKGCONFIG --cflags-only-I libjansson`"
+        APR_ADDTO(CPPFLAGS, [$pkglookup])
+        APR_ADDTO(MOD_CFLAGS, [$pkglookup])
+        pkglookup="`$PKGCONFIG $PKGCONFIG_LIBOPTS --libs-only-L libjansson`"
+        APR_ADDTO(LDFLAGS, [$pkglookup])
+        APR_ADDTO(MOD_LDFLAGS, [$pkglookup])
+        pkglookup="`$PKGCONFIG $PKGCONFIG_LIBOPTS --libs-only-other libjansson`"
+        APR_ADDTO(LDFLAGS, [$pkglookup])
+        APR_ADDTO(MOD_LDFLAGS, [$pkglookup])
+      fi
+      PKG_CONFIG_PATH="$saved_PKG_CONFIG_PATH"
+    fi
+
+    dnl fall back to the user-supplied directory if not found via pkg-config
+    if test "x$ap_jansson_base" != "x" -a "x$ap_jansson_found" = "x"; then
+      APR_ADDTO(CPPFLAGS, [-I$ap_jansson_base/include])
+      APR_ADDTO(MOD_CFLAGS, [-I$ap_jansson_base/include])
+      APR_ADDTO(LDFLAGS, [-L$ap_jansson_base/lib])
+      APR_ADDTO(MOD_LDFLAGS, [-L$ap_jansson_base/lib])
+      if test "x$ap_platform_runtime_link_flag" != "x"; then
+        APR_ADDTO(LDFLAGS, [$ap_platform_runtime_link_flag$ap_jansson_base/lib])
+        APR_ADDTO(MOD_LDFLAGS, [$ap_platform_runtime_link_flag$ap_jansson_base/lib])
+      fi
+    fi
+
+    # attempts to include jansson.h fail me. So lets make sure we can at least
+    # include its other header file
+    AC_TRY_COMPILE([#include <jansson_config.h>],[],
+      [AC_MSG_RESULT(OK) 
+       ac_cv_jansson=yes], 
+       [AC_MSG_RESULT(FAILED)])
+
+    if test "x$ac_cv_jansson" = "xyes"; then
+      ap_jansson_libs="${ap_jansson_libs:--ljansson} `$apr_config --libs`"
+      APR_ADDTO(MOD_LDFLAGS, [$ap_jansson_libs])
+      APR_ADDTO(LIBS, [$ap_jansson_libs])
+    fi
+
+    dnl restore
+    CPPFLAGS="$saved_CPPFLAGS"
+    LIBS="$saved_LIBS"
+    LDFLAGS="$saved_LDFLAGS"
+  ])
+  if test "x$ac_cv_jansson" = "xyes"; then
+    AC_DEFINE(HAVE_JANSSON, 1, [Define if jansson is available])
+  fi
+])
+
+
+dnl #  start of module specific part
+APACHE_MODPATH_INIT(md)
+
+dnl #  list of module object files
+md_objs="dnl
+mod_md.lo dnl
+md_config.lo dnl
+md_core.lo dnl
+md_crypt.lo dnl
+md_curl.lo dnl
+md_http.lo dnl
+md_json.lo dnl
+md_jws.lo dnl
+md_log.lo dnl
+md_os.lo dnl
+md_reg.lo dnl
+md_store.lo dnl
+md_store_fs.lo dnl
+md_util.lo dnl
+md_acme.lo dnl
+md_acme_acct.lo dnl
+md_acme_authz.lo dnl
+md_acme_drive.lo dnl
+"
+
+
+dnl # hook module into the Autoconf mechanism (--enable-md)
+APACHE_MODULE(md, [Managed Domain handling], $md_objs, , most, [
+    APACHE_CHECK_OPENSSL
+    if test "x$ac_cv_openssl" = "xno" ; then
+        AC_MSG_WARN([libssl (or compatible) not found])
+        enable_md=no
+    fi
+    
+    APACHE_CHECK_JANSSON
+    if test "x$ac_cv_jansson" != "xyes" ; then
+        AC_MSG_WARN([libjansson not found])
+        enable_md=no
+    fi
+
+    APACHE_CHECK_CURL
+    if test "x$ac_cv_curl" != "xyes" ; then
+        AC_MSG_WARN([libcurl not found])
+        enable_md=no
+    fi
+])
+
+# Ensure that other modules can pick up mod_md.h
+APR_ADDTO(INCLUDES, [-I\$(top_srcdir)/$modpath_current])
+
+
+
+dnl #  end of module specific part
+APACHE_MODPATH_FINISH
+
diff --git a/modules/md/md.h b/modules/md/md.h
new file mode 100644
index 0000000000..23b7543a78
--- /dev/null
+++ b/modules/md/md.h
@@ -0,0 +1,230 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_h
+#define mod_md_md_h
+
+#include "md_version.h"
+
+struct apr_array_header_t;
+struct apr_hash_t;
+struct md_json_t;
+struct md_cert_t;
+struct md_pkey_t;
+struct md_store_t;
+
+#define MD_TLSSNI01_DNS_SUFFIX     ".acme.invalid"
+
+typedef enum {
+    MD_S_UNKNOWN,                   /* MD has not been analysed yet */
+    MD_S_INCOMPLETE,                /* MD is missing necessary information, cannot go live */
+    MD_S_COMPLETE,                  /* MD has all necessary information, can go live */
+    MD_S_EXPIRED,                   /* MD is complete, but credentials have expired */
+    MD_S_ERROR,                     /* MD data is flawed, unable to be processed as is */ 
+} md_state_t;
+
+typedef enum {
+    MD_SV_TEXT,
+    MD_SV_JSON,
+    MD_SV_CERT,
+    MD_SV_PKEY,
+    MD_SV_CHAIN,
+} md_store_vtype_t;
+
+typedef enum {
+    MD_SG_NONE,
+    MD_SG_ACCOUNTS,
+    MD_SG_CHALLENGES,
+    MD_SG_DOMAINS,
+    MD_SG_STAGING,
+    MD_SG_ARCHIVE,
+    MD_SG_TMP,
+    MD_SG_COUNT,
+} md_store_group_t;
+
+typedef enum {
+    MD_DRIVE_DEFAULT = -1,          /* default value */
+    MD_DRIVE_MANUAL,                /* manually triggered transmission of credentials */
+    MD_DRIVE_AUTO,                  /* automatic process performed by httpd */
+    MD_DRIVE_ALWAYS,                /* always driven by httpd, even if not used in any vhost */
+} md_drive_mode_t;
+
+typedef struct md_t md_t;
+struct md_t {
+    const char *name;               /* unique name of this MD */
+    md_state_t state;               /* state of this MD */
+    apr_time_t expires;             /* When the credentials for this domain expire. 0 if unknown */
+    apr_interval_time_t renew_window;/* time before expiration that starts renewal */
+    
+    struct apr_array_header_t *domains; /* all DNS names this MD includes */
+    md_drive_mode_t drive_mode;     /* mode of obtaining credentials */
+    int must_staple;                /* certificates should set the OCSP Must Staple extension */
+    
+    const char *ca_url;             /* url of CA certificate service */
+    const char *ca_proto;           /* protocol used vs CA (e.g. ACME) */
+    const char *ca_account;         /* account used at CA */
+    const char *ca_agreement;       /* accepted agreement uri between CA and user */ 
+    struct apr_array_header_t *ca_challenges; /* challenge types configured for this MD */
+    struct apr_array_header_t *contacts;   /* list of contact uris, e.g. mailto:xxx */
+
+    const char *cert_url;           /* url where cert has been created, remember during drive */ 
+
+    const char *defn_name;          /* config file this MD was defined */
+    unsigned defn_line_number;      /* line number of definition */
+};
+
+#define MD_KEY_ACCOUNT          "account"
+#define MD_KEY_AGREEMENT        "agreement"
+#define MD_KEY_CA               "ca"
+#define MD_KEY_CA_URL           "ca-url"
+#define MD_KEY_CERT             "cert"
+#define MD_KEY_CHALLENGES       "challenges"
+#define MD_KEY_CONTACT          "contact"
+#define MD_KEY_CONTACTS         "contacts"
+#define MD_KEY_CSR              "csr"
+#define MD_KEY_DISABLED         "disabled"
+#define MD_KEY_DIR              "dir"
+#define MD_KEY_DOMAIN           "domain"
+#define MD_KEY_DOMAINS          "domains"
+#define MD_KEY_DRIVE_MODE       "drive-mode"
+#define MD_KEY_EXPIRES          "expires"
+#define MD_KEY_HTTP             "http"
+#define MD_KEY_HTTPS            "https"
+#define MD_KEY_ID               "id"
+#define MD_KEY_IDENTIFIER       "identifier"
+#define MD_KEY_KEY              "key"
+#define MD_KEY_KEYAUTHZ         "keyAuthorization"
+#define MD_KEY_LOCATION         "location"
+#define MD_KEY_NAME             "name"
+#define MD_KEY_PROTO            "proto"
+#define MD_KEY_REGISTRATION     "registration"
+#define MD_KEY_RENEW_WINDOW     "renew-window"
+#define MD_KEY_RESOURCE         "resource"
+#define MD_KEY_STATE            "state"
+#define MD_KEY_STATUS           "status"
+#define MD_KEY_TOKEN            "token"
+#define MD_KEY_TYPE             "type"
+#define MD_KEY_URL              "url"
+#define MD_KEY_URI              "uri"
+#define MD_KEY_VALUE            "value"
+#define MD_KEY_VERSION          "version"
+
+#define MD_FN_MD                "md.json"
+#define MD_FN_PKEY              "pkey.pem"
+#define MD_FN_CERT              "cert.pem"
+#define MD_FN_CHAIN             "chain.pem"
+#define MD_FN_HTTPD_JSON        "httpd.json"
+
+/* Check if a string member of a new MD (n) has 
+ * a value and if it differs from the old MD o
+ */
+#define MD_VAL_UPDATE(n,o,s)    ((n)->s != (o)->s)
+#define MD_SVAL_UPDATE(n,o,s)   ((n)->s && (!(o)->s || strcmp((n)->s, (o)->s)))
+
+#define MD_SECS_PER_HOUR      (60*60)
+#define MD_SECS_PER_DAY       (24*MD_SECS_PER_HOUR)
+
+/**
+ * Determine if the Managed Domain contains a specific domain name.
+ */
+int md_contains(const md_t *md, const char *domain);
+
+/**
+ * Determine if the names of the two managed domains overlap.
+ */
+int md_domains_overlap(const md_t *md1, const md_t *md2);
+
+/**
+ * Determine if the domain names are equal.
+ */
+int md_equal_domains(const md_t *md1, const md_t *md2);
+
+/**
+ * Determine if the domains in md1 contain all domains of md2.
+ */
+int md_contains_domains(const md_t *md1, const md_t *md2);
+
+/**
+ * Get one common domain name of the two managed domains or NULL.
+ */
+const char *md_common_name(const md_t *md1, const md_t *md2);
+
+/**
+ * Get the number of common domains.
+ */
+apr_size_t md_common_name_count(const md_t *md1, const md_t *md2);
+
+/**
+ * Look up a managed domain by its name.
+ */
+md_t *md_get_by_name(struct apr_array_header_t *mds, const char *name);
+
+/**
+ * Look up a managed domain by a DNS name it contains.
+ */
+md_t *md_get_by_domain(struct apr_array_header_t *mds, const char *domain);
+
+/**
+ * Find a managed domain, different from the given one, that has overlaps
+ * in the domain list.
+ */
+md_t *md_get_by_dns_overlap(struct apr_array_header_t *mds, const md_t *md);
+
+/**
+ * Find the managed domain in the list that has the most overlaps in domains to the
+ * given md.
+ */
+md_t *md_find_closest_match(apr_array_header_t *mds, const md_t *md);
+
+/**
+ * Create and empty md record, structures initialized.
+ */
+md_t *md_create_empty(apr_pool_t *p);
+
+/**
+ * Create a managed domain, given a list of domain names.
+ */
+const char *md_create(md_t **pmd, apr_pool_t *p, struct apr_array_header_t *domains);
+
+/**
+ * Deep copy an md record into another pool.
+ */
+md_t *md_clone(apr_pool_t *p, const md_t *src);
+
+/**
+ * Shallow copy an md record into another pool.
+ */
+md_t *md_copy(apr_pool_t *p, const md_t *src);
+
+/** 
+ * Convert the managed domain into a JSON representation and vice versa. 
+ *
+ * This reads and writes the following information: name, domains, ca_url, ca_proto and state.
+ */
+struct md_json_t *md_to_json (const md_t *md, apr_pool_t *p);
+md_t *md_from_json(struct md_json_t *json, apr_pool_t *p);
+
+/**************************************************************************************************/
+/* domain credentials */
+
+typedef struct md_creds_t md_creds_t;
+struct md_creds_t {
+    struct md_cert_t *cert;
+    struct md_pkey_t *pkey;
+    struct apr_array_header_t *chain;      /* list of md_cert* */
+    int expired;
+};
+
+#endif /* mod_md_md_h */
diff --git a/modules/md/md_acme.c b/modules/md/md_acme.c
new file mode 100644
index 0000000000..6eedb55d2a
--- /dev/null
+++ b/modules/md/md_acme.c
@@ -0,0 +1,506 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_buckets.h>
+#include <apr_hash.h>
+#include <apr_uri.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_json.h"
+#include "md_jws.h"
+#include "md_http.h"
+#include "md_log.h"
+#include "md_store.h"
+#include "md_util.h"
+#include "md_version.h"
+
+#include "md_acme.h"
+#include "md_acme_acct.h"
+
+
+static const char *base_product;
+
+typedef struct acme_problem_status_t acme_problem_status_t;
+
+struct acme_problem_status_t {
+    const char *type;
+    apr_status_t rv;
+};
+
+static acme_problem_status_t Problems[] = {
+    { "acme:error:badCSR",                       APR_EINVAL },
+    { "acme:error:badNonce",                     APR_EAGAIN },
+    { "acme:error:badSignatureAlgorithm",        APR_EINVAL },
+    { "acme:error:invalidContact",               APR_BADARG },
+    { "acme:error:unsupportedContact",           APR_EGENERAL },
+    { "acme:error:malformed",                    APR_EINVAL },
+    { "acme:error:rateLimited",                  APR_BADARG },
+    { "acme:error:rejectedIdentifier",           APR_BADARG },
+    { "acme:error:serverInternal",               APR_EGENERAL },
+    { "acme:error:unauthorized",                 APR_EACCES },
+    { "acme:error:unsupportedIdentifier",        APR_BADARG },
+    { "acme:error:userActionRequired",           APR_EAGAIN },
+    { "acme:error:badRevocationReason",          APR_EINVAL },
+    { "acme:error:caa",                          APR_EGENERAL },
+    { "acme:error:dns",                          APR_EGENERAL },
+    { "acme:error:connection",                   APR_EGENERAL },
+    { "acme:error:tls",                          APR_EGENERAL },
+    { "acme:error:incorrectResponse",            APR_EGENERAL },
+};
+
+static apr_status_t problem_status_get(const char *type) {
+    int i;
+
+    if (strstr(type, "urn:ietf:params:") == type) {
+        type += strlen("urn:ietf:params:");
+    }
+    else if (strstr(type, "urn:") == type) {
+        type += strlen("urn:");
+    }
+     
+    for(i = 0; i < (sizeof(Problems)/sizeof(Problems[0])); ++i) {
+        if (!apr_strnatcasecmp(type, Problems[i].type)) {
+            return Problems[i].rv;
+        }
+    }
+    return APR_EGENERAL;
+}
+
+apr_status_t md_acme_init(apr_pool_t *p, const char *base)
+{
+    base_product = base;
+    return md_crypt_init(p);
+}
+
+apr_status_t md_acme_create(md_acme_t **pacme, apr_pool_t *p, const char *url)
+{
+    md_acme_t *acme;
+    const char *err = NULL;
+    apr_status_t rv;
+    apr_uri_t uri_parsed;
+    size_t len;
+    
+    if (!url) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, p, "create ACME without url");
+        return APR_EINVAL;
+    }
+    
+    if (APR_SUCCESS != (rv = md_util_abs_uri_check(p, url, &err))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "invalid ACME uri ($s): %s", err, url);
+        return rv;
+    }
+    
+    acme = apr_pcalloc(p, sizeof(*acme));
+    acme->url = url;
+    acme->p = p;
+    acme->user_agent = apr_psprintf(p, "%s mod_md/%s (Something, like certbot)", 
+                                    base_product, MOD_MD_VERSION);
+    acme->pkey_bits = 4096;
+    acme->max_retries = 3;
+    
+    if (APR_SUCCESS != (rv = apr_uri_parse(p, url, &uri_parsed))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "parsing ACME uri: ", url);
+        return APR_EINVAL;
+    }
+    
+    len = strlen(uri_parsed.hostname);
+    acme->sname = (len <= 16)? uri_parsed.hostname : apr_pstrdup(p, uri_parsed.hostname + len - 16);
+    
+    *pacme = (APR_SUCCESS == rv)? acme : NULL;
+    return rv;
+}
+
+apr_status_t md_acme_setup(md_acme_t *acme)
+{
+    apr_status_t rv;
+    md_json_t *json;
+    
+    assert(acme->url);
+    if (!acme->http && APR_SUCCESS != (rv = md_http_create(&acme->http, acme->p,
+                                                           acme->user_agent))) {
+        return rv;
+    }
+    md_http_set_response_limit(acme->http, 1024*1024);
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, acme->p, "get directory from %s", acme->url);
+    
+    rv = md_acme_get_json(&json, acme, acme->url, acme->p);
+    if (APR_SUCCESS == rv) {
+        acme->new_authz = md_json_gets(json, "new-authz", NULL);
+        acme->new_cert = md_json_gets(json, "new-cert", NULL);
+        acme->new_reg = md_json_gets(json, "new-reg", NULL);
+        acme->revoke_cert = md_json_gets(json, "revoke-cert", NULL);
+        if (acme->new_authz && acme->new_cert && acme->new_reg && acme->revoke_cert) {
+            return APR_SUCCESS;
+        }
+        rv = APR_EINVAL;
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* acme requests */
+
+static void req_update_nonce(md_acme_t *acme, apr_table_t *hdrs)
+{
+    if (hdrs) {
+        const char *nonce = apr_table_get(hdrs, "Replay-Nonce");
+        if (nonce) {
+            acme->nonce = apr_pstrdup(acme->p, nonce);
+        }
+    }
+}
+
+static apr_status_t http_update_nonce(const md_http_response_t *res)
+{
+    if (res->headers) {
+        const char *nonce = apr_table_get(res->headers, "Replay-Nonce");
+        if (nonce) {
+            md_acme_t *acme = res->req->baton;
+            acme->nonce = apr_pstrdup(acme->p, nonce);
+        }
+    }
+    return res->rv;
+}
+
+static apr_status_t md_acme_new_nonce(md_acme_t *acme)
+{
+    apr_status_t rv;
+    long id;
+    
+    rv = md_http_HEAD(acme->http, acme->new_reg, NULL, http_update_nonce, acme, &id);
+    md_http_await(acme->http, id);
+    return rv;
+}
+
+static md_acme_req_t *md_acme_req_create(md_acme_t *acme, const char *method, const char *url)
+{
+    apr_pool_t *pool;
+    md_acme_req_t *req;
+    apr_status_t rv;
+    
+    rv = apr_pool_create(&pool, acme->p);
+    if (rv != APR_SUCCESS) {
+        return NULL;
+    }
+    
+    req = apr_pcalloc(pool, sizeof(*req));
+    if (!req) {
+        apr_pool_destroy(pool);
+        return NULL;
+    }
+        
+    req->acme = acme;
+    req->p = pool;
+    req->method = method;
+    req->url = url;
+    req->prot_hdrs = apr_table_make(pool, 5);
+    if (!req->prot_hdrs) {
+        apr_pool_destroy(pool);
+        return NULL;
+    }
+    req->max_retries = acme->max_retries;
+    
+    return req;
+}
+ 
+apr_status_t md_acme_req_body_init(md_acme_req_t *req, md_json_t *jpayload)
+{
+    const char *payload;
+    size_t payload_len;
+
+    if (!req->acme->acct) {
+        return APR_EINVAL;
+    }
+
+    payload = md_json_writep(jpayload, req->p, MD_JSON_FMT_COMPACT);
+    if (!payload) {
+        return APR_EINVAL;
+    }
+
+    payload_len = strlen(payload);
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, req->p, 
+                  "acct payload(len=%d): %s", payload_len, payload);
+    return md_jws_sign(&req->req_json, req->p, payload, payload_len,
+                       req->prot_hdrs, req->acme->acct_key, NULL);
+} 
+
+
+static apr_status_t inspect_problem(md_acme_req_t *req, const md_http_response_t *res)
+{
+    const char *ctype;
+    md_json_t *problem;
+    
+    ctype = apr_table_get(req->resp_hdrs, "content-type");
+    if (ctype && !strcmp(ctype, "application/problem+json")) {
+        /* RFC 7807 */
+        md_json_read_http(&problem, req->p, res);
+        if (problem) {
+            const char *ptype, *pdetail;
+            
+            req->resp_json = problem;
+            ptype = md_json_gets(problem, "type", NULL); 
+            pdetail = md_json_gets(problem, "detail", NULL);
+            req->rv = problem_status_get(ptype);
+             
+            md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, req->rv, req->p,
+                          "acme problem %s: %s", ptype, pdetail);
+            return req->rv;
+        }
+    }
+    
+    if (APR_SUCCESS == res->rv) {
+        switch (res->status) {
+            case 400:
+                return APR_EINVAL;
+            case 403:
+                return APR_EACCES;
+            case 404:
+                return APR_ENOENT;
+            default:
+                md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, req->p,
+                              "acme problem unknonw: http status %d", res->status);
+                return APR_EGENERAL;
+        }
+    }
+    return res->rv;
+}
+
+/**************************************************************************************************/
+/* ACME requests with nonce handling */
+
+static apr_status_t md_acme_req_done(md_acme_req_t *req)
+{
+    apr_status_t rv = req->rv;
+    if (req->p) {
+        apr_pool_destroy(req->p);
+    }
+    return rv;
+}
+
+static apr_status_t on_response(const md_http_response_t *res)
+{
+    md_acme_req_t *req = res->req->baton;
+    apr_status_t rv = res->rv;
+    
+    if (APR_SUCCESS != rv) {
+        goto out;
+    }
+    
+    req->resp_hdrs = apr_table_clone(req->p, res->headers);
+    req_update_nonce(req->acme, res->headers);
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, rv, req->p, "response: %d", res->status);
+    if (res->status >= 200 && res->status < 300) {
+        int processed = 0;
+        
+        if (req->on_json) {
+            processed = 1;
+            rv = md_json_read_http(&req->resp_json, req->p, res);
+            if (APR_SUCCESS == rv) {
+                if (md_log_is_level(req->p, MD_LOG_TRACE2)) {
+                    const char *s;
+                    s = md_json_writep(req->resp_json, req->p, MD_JSON_FMT_INDENT);
+                    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE2, rv, req->p,
+                                  "response: %s",
+                                  s ? s : "<failed to serialize!>");
+                }
+                rv = req->on_json(req->acme, req->p, req->resp_hdrs, req->resp_json, req->baton);
+            }        
+            else if (APR_STATUS_IS_ENOENT(rv)) {
+                /* not JSON content, fall through */
+                processed = 0;
+            }
+            else {
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, req->p, "parsing JSON body");
+            }
+        }
+        
+        if (!processed && req->on_res) {
+            processed = 1;
+            rv = req->on_res(req->acme, res, req->baton);
+        }
+        
+        if (!processed) {
+            rv = APR_EINVAL;
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, req->p, 
+                          "response: %d, content-type=%s", res->status, 
+                          apr_table_get(res->headers, "Content-Type"));
+        }
+    }
+    else if (APR_EAGAIN == (rv = inspect_problem(req, res))) {
+        /* leave req alive */
+        return rv;
+    }
+
+out:
+    md_acme_req_done(req);
+    return rv;
+}
+
+static apr_status_t md_acme_req_send(md_acme_req_t *req)
+{
+    apr_status_t rv;
+    md_acme_t *acme = req->acme;
+    const char *body = NULL;
+
+    assert(acme->url);
+    
+    if (strcmp("GET", req->method) && strcmp("HEAD", req->method)) {
+        if (!acme->new_authz) {
+            if (APR_SUCCESS != (rv = md_acme_setup(acme))) {
+                return rv;
+            }
+        }
+        if (!acme->nonce) {
+            if (APR_SUCCESS != (rv = md_acme_new_nonce(acme))) {
+                return rv;
+            }
+        }
+        
+        apr_table_set(req->prot_hdrs, "nonce", acme->nonce);
+        acme->nonce = NULL;
+    }
+    
+    rv = req->on_init? req->on_init(req, req->baton) : APR_SUCCESS;
+    
+    if ((rv == APR_SUCCESS) && req->req_json) {
+        body = md_json_writep(req->req_json, req->p, MD_JSON_FMT_INDENT);
+        if (!body) {
+            rv = APR_EINVAL;
+        }
+    }
+
+    if (rv == APR_SUCCESS) {
+        long id = 0;
+        
+        if (body && md_log_is_level(req->p, MD_LOG_TRACE2)) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_TRACE2, 0, req->p, 
+                          "req: POST %s, body:\n%s", req->url, body);
+        }
+        else {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, req->p, 
+                          "req: POST %s", req->url);
+        }
+        if (!strcmp("GET", req->method)) {
+            rv = md_http_GET(req->acme->http, req->url, NULL, on_response, req, &id);
+        }
+        else if (!strcmp("POST", req->method)) {
+            rv = md_http_POSTd(req->acme->http, req->url, NULL, "application/json",  
+                               body, body? strlen(body) : 0, on_response, req, &id);
+        }
+        else if (!strcmp("HEAD", req->method)) {
+            rv = md_http_HEAD(req->acme->http, req->url, NULL, on_response, req, &id);
+        }
+        else {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, req->p, 
+                          "HTTP method %s against: %s", req->method, req->url);
+            rv = APR_ENOTIMPL;
+        }
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, req->p, "req sent");
+        md_http_await(acme->http, id);
+        
+        if (APR_EAGAIN == rv && req->max_retries > 0) {
+            --req->max_retries;
+            return md_acme_req_send(req);
+        }
+        req = NULL;
+    }
+
+    if (req) {
+        md_acme_req_done(req);
+    }
+    return rv;
+}
+
+apr_status_t md_acme_POST(md_acme_t *acme, const char *url,
+                          md_acme_req_init_cb *on_init,
+                          md_acme_req_json_cb *on_json,
+                          md_acme_req_res_cb *on_res,
+                          void *baton)
+{
+    md_acme_req_t *req;
+    
+    assert(url);
+    assert(on_json || on_res);
+
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, acme->p, "add acme POST: %s", url);
+    req = md_acme_req_create(acme, "POST", url);
+    req->on_init = on_init;
+    req->on_json = on_json;
+    req->on_res = on_res;
+    req->baton = baton;
+    
+    return md_acme_req_send(req);
+}
+
+apr_status_t md_acme_GET(md_acme_t *acme, const char *url,
+                         md_acme_req_init_cb *on_init,
+                         md_acme_req_json_cb *on_json,
+                         md_acme_req_res_cb *on_res,
+                         void *baton)
+{
+    md_acme_req_t *req;
+    
+    assert(url);
+    assert(on_json || on_res);
+
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, acme->p, "add acme GET: %s", url);
+    req = md_acme_req_create(acme, "GET", url);
+    req->on_init = on_init;
+    req->on_json = on_json;
+    req->on_res = on_res;
+    req->baton = baton;
+    
+    return md_acme_req_send(req);
+}
+
+/**************************************************************************************************/
+/* GET JSON */
+
+typedef struct {
+    apr_pool_t *pool;
+    md_json_t *json;
+} json_ctx;
+
+static apr_status_t on_got_json(md_acme_t *acme, apr_pool_t *p, const apr_table_t *headers, 
+                                md_json_t *jbody, void *baton)
+{
+    json_ctx *ctx = baton;
+    
+    ctx->json = md_json_clone(ctx->pool, jbody);
+    return APR_SUCCESS;
+}
+
+apr_status_t md_acme_get_json(struct md_json_t **pjson, md_acme_t *acme, 
+                              const char *url, apr_pool_t *p)
+{
+    apr_status_t rv;
+    json_ctx ctx;
+    
+    ctx.pool = p;
+    ctx.json = NULL;
+    
+    rv = md_acme_GET(acme, url, NULL, on_got_json, NULL, &ctx);
+    *pjson = (APR_SUCCESS == rv)? ctx.json : NULL;
+    return rv;
+}
+
diff --git a/modules/md/md_acme.h b/modules/md/md_acme.h
new file mode 100644
index 0000000000..a5a57aab88
--- /dev/null
+++ b/modules/md/md_acme.h
@@ -0,0 +1,260 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_acme_h
+#define mod_md_md_acme_h
+
+struct apr_array_header_t;
+struct apr_bucket_brigade;
+struct md_http_response_t;
+struct apr_hash_t;
+struct md_http_t;
+struct md_json_t;
+struct md_pkey_t;
+struct md_t;
+struct md_acme_acct_t;
+struct md_proto_t;
+struct md_store_t;
+
+#define MD_PROTO_ACME               "ACME"
+
+#define MD_AUTHZ_CHA_HTTP_01        "http-01"
+#define MD_AUTHZ_CHA_SNI_01         "tls-sni-01"
+
+typedef enum {
+    MD_ACME_S_UNKNOWN,              /* MD has not been analysed yet */
+    MD_ACME_S_REGISTERED,           /* MD is registered at CA, but not more */
+    MD_ACME_S_TOS_ACCEPTED,         /* Terms of Service were accepted by account holder */
+    MD_ACME_S_CHALLENGED,           /* MD challenge information for all domains is known */
+    MD_ACME_S_VALIDATED,            /* MD domains have been validated */
+    MD_ACME_S_CERTIFIED,            /* MD has valid certificate */
+    MD_ACME_S_DENIED,               /* MD domains (at least one) have been denied by CA */
+} md_acme_state_t;
+
+typedef struct md_acme_t md_acme_t;
+
+struct md_acme_t {
+    const char *url;                /* directory url of the ACME service */
+    const char *sname;              /* short name for the service, not necessarily unique */
+    apr_pool_t *p;
+    const char *user_agent;
+    struct md_acme_acct_t *acct;
+    struct md_pkey_t *acct_key;
+    
+    const char *new_authz;
+    const char *new_cert;
+    const char *new_reg;
+    const char *revoke_cert;
+    
+    struct md_http_t *http;
+    
+    const char *nonce;
+    int max_retries;
+    unsigned int pkey_bits;
+};
+
+/**
+ * Global init, call once at start up.
+ */
+apr_status_t md_acme_init(apr_pool_t *pool, const char *base_version);
+
+/**
+ * Create a new ACME server instance. If path is not NULL, will use that directory
+ * for persisting information. Will load any inforation persisted in earlier session.
+ * url needs only be specified for instances where this has never been persisted before.
+ *
+ * @param pacme   will hold the ACME server instance on success
+ * @param p       pool to used
+ * @param url     url of the server, optional if known at path
+ */
+apr_status_t md_acme_create(md_acme_t **pacme, apr_pool_t *p, const char *url);
+
+/**
+ * Contact the ACME server and retrieve its directory information.
+ * 
+ * @param acme    the ACME server to contact
+ */
+apr_status_t md_acme_setup(md_acme_t *acme);
+
+/**************************************************************************************************/
+/* account handling */
+
+#define MD_ACME_ACCT_STAGED     "staged"
+
+apr_status_t md_acme_acct_load(struct md_acme_acct_t **pacct, struct md_pkey_t **ppkey,
+                               struct md_store_t *store, md_store_group_t group, 
+                               const char *name, apr_pool_t *p);
+
+/** 
+ * Specify the account to use by name in local store. On success, the account
+ * the "current" one used by the acme instance.
+ */
+apr_status_t md_acme_use_acct(md_acme_t *acme, struct md_store_t *store, 
+                              apr_pool_t *p, const char *acct_id);
+
+apr_status_t md_acme_use_acct_staged(md_acme_t *acme, struct md_store_t *store, 
+                                     md_t *md, apr_pool_t *p);
+
+/**
+ * Get the local name of the account currently used by the acme instance.
+ * Will be NULL if no account has been setup successfully.
+ */
+const char *md_acme_get_acct(md_acme_t *acme, apr_pool_t *p);
+
+/**
+ * Agree to the given Terms-of-Service url for the current account.
+ */
+apr_status_t md_acme_agree(md_acme_t *acme, apr_pool_t *p, const char *tos);
+
+/**
+ * Confirm with the server that the current account agrees to the Terms-of-Service
+ * given in the agreement url.
+ * If the known agreement is equal to this, nothing is done.
+ * If it differs, the account is re-validated in the hope that the server
+ * accounces the Tos URL it wants. If this is equal to the agreement specified,
+ * the server is notified of this. If the server requires a ToS that the account
+ * thinks it has already given, it is resend.
+ */
+apr_status_t md_acme_check_agreement(md_acme_t *acme, apr_pool_t *p, const char *agreement);
+
+/**
+ * Get the ToS agreement for current account.
+ */
+const char *md_acme_get_agreement(md_acme_t *acme);
+
+
+/** 
+ * Find an existing account in the local store. On APR_SUCCESS, the acme
+ * instance will have a current, validated account to use.
+ */ 
+apr_status_t md_acme_find_acct(md_acme_t *acme, struct md_store_t *store, apr_pool_t *p);
+
+/**
+ * Create a new account at the ACME server. The
+ * new account is the one used by the acme instance afterwards, on success.
+ */
+apr_status_t md_acme_create_acct(md_acme_t *acme, apr_pool_t *p, apr_array_header_t *contacts, 
+                                 const char *agreement);
+
+apr_status_t md_acme_acct_save(struct md_store_t *store, apr_pool_t *p, md_acme_t *acme,  
+                               struct md_acme_acct_t *acct, struct md_pkey_t *acct_key);
+                               
+apr_status_t md_acme_save(md_acme_t *acme, struct md_store_t *store, apr_pool_t *p);
+
+apr_status_t md_acme_acct_save_staged(md_acme_t *acme, struct md_store_t *store, 
+                                      md_t *md, apr_pool_t *p);
+
+/**
+ * Delete the current account at the ACME server and remove it from store. 
+ */
+apr_status_t md_acme_delete_acct(md_acme_t *acme, struct md_store_t *store, apr_pool_t *p);
+
+/**
+ * Delete the account from the local store without contacting the ACME server.
+ */
+apr_status_t md_acme_unstore_acct(struct md_store_t *store, apr_pool_t *p, const char *acct_id);
+
+/**************************************************************************************************/
+/* request handling */
+
+/**
+ * Request callback on a successfull HTTP response (status 2xx).
+ */
+typedef apr_status_t md_acme_req_res_cb(md_acme_t *acme, 
+                                        const struct md_http_response_t *res, void *baton);
+
+/**
+ * A request against an ACME server
+ */
+typedef struct md_acme_req_t md_acme_req_t;
+
+/**
+ * Request callback to initialize before sending. May be invoked more than once in
+ * case of retries.
+ */
+typedef apr_status_t md_acme_req_init_cb(md_acme_req_t *req, void *baton);
+
+/**
+ * Request callback on a successfull response (HTTP response code 2xx) and content
+ * type matching application/.*json.
+ */
+typedef apr_status_t md_acme_req_json_cb(md_acme_t *acme, apr_pool_t *p, 
+                                         const apr_table_t *headers, 
+                                         struct md_json_t *jbody, void *baton);
+
+struct md_acme_req_t {
+    md_acme_t *acme;               /* the ACME server to talk to */
+    apr_pool_t *p;                 /* pool for the request duration */
+    
+    const char *url;               /* url to POST the request to */
+    const char *method;            /* HTTP method to use */
+    apr_table_t *prot_hdrs;        /* JWS headers needing protection (nonce) */
+    struct md_json_t *req_json;    /* JSON to be POSTed in request body */
+
+    apr_table_t *resp_hdrs;        /* HTTP response headers */
+    struct md_json_t *resp_json;   /* JSON response body recevied */
+    
+    apr_status_t rv;               /* status of request */
+    
+    md_acme_req_init_cb *on_init;  /* callback to initialize the request before submit */
+    md_acme_req_json_cb *on_json;  /* callback on successful JSON response */
+    md_acme_req_res_cb *on_res;    /* callback on generic HTTP response */
+    int max_retries;               /* how often this might be retried */
+    void *baton;                   /* userdata for callbacks */
+};
+
+apr_status_t md_acme_GET(md_acme_t *acme, const char *url,
+                         md_acme_req_init_cb *on_init,
+                         md_acme_req_json_cb *on_json,
+                         md_acme_req_res_cb *on_res,
+                         void *baton);
+/**
+ * Perform a POST against the ACME url. If a on_json callback is given and
+ * the HTTP response is JSON, only this callback is invoked. Otherwise, on HTTP status
+ * 2xx, the on_res callback is invoked. If no on_res is given, it is considered a
+ * response error, since only JSON was expected.
+ * At least one callback needs to be non-NULL.
+ * 
+ * @param acme        the ACME server to talk to
+ * @param url         the url to send the request to
+ * @param on_init     callback to initialize the request data
+ * @param on_json     callback on successful JSON response
+ * @param on_res      callback on successful HTTP response
+ * @param baton       userdata for callbacks
+ */
+apr_status_t md_acme_POST(md_acme_t *acme, const char *url,
+                          md_acme_req_init_cb *on_init,
+                          md_acme_req_json_cb *on_json,
+                          md_acme_req_res_cb *on_res,
+                          void *baton);
+
+apr_status_t md_acme_GET(md_acme_t *acme, const char *url,
+                         md_acme_req_init_cb *on_init,
+                         md_acme_req_json_cb *on_json,
+                         md_acme_req_res_cb *on_res,
+                         void *baton);
+
+/**
+ * Retrieve a JSON resource from the ACME server 
+ */
+apr_status_t md_acme_get_json(struct md_json_t **pjson, md_acme_t *acme, 
+                              const char *url, apr_pool_t *p);
+
+
+apr_status_t md_acme_req_body_init(md_acme_req_t *req, struct md_json_t *jpayload);
+
+apr_status_t md_acme_protos_add(struct apr_hash_t *protos, apr_pool_t *p);
+
+#endif /* md_acme_h */
diff --git a/modules/md/md_acme_acct.c b/modules/md/md_acme_acct.c
new file mode 100644
index 0000000000..71246c3f86
--- /dev/null
+++ b/modules/md/md_acme_acct.c
@@ -0,0 +1,652 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+
+#include <apr_lib.h>
+#include <apr_file_info.h>
+#include <apr_file_io.h>
+#include <apr_fnmatch.h>
+#include <apr_hash.h>
+#include <apr_strings.h>
+#include <apr_tables.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_json.h"
+#include "md_jws.h"
+#include "md_log.h"
+#include "md_store.h"
+#include "md_util.h"
+#include "md_version.h"
+
+#include "md_acme.h"
+#include "md_acme_acct.h"
+
+static apr_status_t acct_make(md_acme_acct_t **pacct, apr_pool_t *p, 
+                              const char *ca_url, const char *id, apr_array_header_t *contacts)
+{
+    md_acme_acct_t *acct;
+    
+    acct = apr_pcalloc(p, sizeof(*acct));
+
+    acct->id = id? apr_pstrdup(p, id) : NULL;
+    acct->ca_url = ca_url;
+    
+    if (!contacts || apr_is_empty_array(contacts)) {
+        acct->contacts = apr_array_make(p, 5, sizeof(const char *));
+    }
+    else {
+        acct->contacts = apr_array_copy(p, contacts);
+    }
+    
+    *pacct = acct;
+    return APR_SUCCESS;
+}
+
+
+static void md_acme_acct_free(md_acme_acct_t *acct)
+{
+}
+
+static const char *mk_acct_id(apr_pool_t *p, md_acme_t *acme, int i)
+{
+    return apr_psprintf(p, "ACME-%s-%04d", acme->sname, i);
+}
+
+static const char *mk_acct_pattern(apr_pool_t *p, md_acme_t *acme)
+{
+    return apr_psprintf(p, "ACME-%s-*", acme->sname);
+}
+ 
+/**************************************************************************************************/
+/* json load/save */
+
+static md_json_t *acct_to_json(md_acme_acct_t *acct, apr_pool_t *p)
+{
+    md_json_t *jacct;
+
+    assert(acct);
+    jacct = md_json_create(p);
+    md_json_sets(acct->id, jacct, MD_KEY_ID, NULL);
+    md_json_setb(acct->disabled, jacct, MD_KEY_DISABLED, NULL);
+    md_json_sets(acct->url, jacct, MD_KEY_URL, NULL);
+    md_json_sets(acct->ca_url, jacct, MD_KEY_CA_URL, NULL);
+    md_json_setj(acct->registration, jacct, MD_KEY_REGISTRATION, NULL);
+    if (acct->agreement) {
+        md_json_sets(acct->agreement, jacct, MD_KEY_AGREEMENT, NULL);
+    }
+    
+    return jacct;
+}
+
+static apr_status_t acct_from_json(md_acme_acct_t **pacct, md_json_t *json, apr_pool_t *p)
+{
+    apr_status_t rv = APR_EINVAL;
+    md_acme_acct_t *acct;
+    int disabled;
+    const char *ca_url, *url, *id;
+    apr_array_header_t *contacts;
+    
+    id = md_json_gets(json, MD_KEY_ID, NULL);
+    disabled = md_json_getb(json, MD_KEY_DISABLED, NULL);
+    ca_url = md_json_gets(json, MD_KEY_CA_URL, NULL);
+    if (!ca_url) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "account has no CA url: %s", id);
+        goto out;
+    }
+    
+    url = md_json_gets(json, MD_KEY_URL, NULL);
+    if (!url) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "account has no url: %s", id);
+        goto out;
+    }
+
+    contacts = apr_array_make(p, 5, sizeof(const char *));
+    md_json_getsa(contacts, json, MD_KEY_REGISTRATION, MD_KEY_CONTACT, NULL);
+    rv = acct_make(&acct, p, ca_url, id, contacts);
+    if (APR_SUCCESS == rv) {
+        acct->disabled = disabled;
+        acct->url = url;
+        acct->agreement = md_json_gets(json, "terms-of-service", NULL);
+    }
+
+out:
+    *pacct = (APR_SUCCESS == rv)? acct : NULL;
+    return rv;
+}
+
+apr_status_t md_acme_acct_save_staged(md_acme_t *acme, md_store_t *store, md_t *md, apr_pool_t *p)
+{
+    md_acme_acct_t *acct = acme->acct;
+    md_json_t *jacct;
+    apr_status_t rv;
+    
+    jacct = acct_to_json(acct, p);
+    
+    rv = md_store_save(store, p, MD_SG_STAGING, md->name, MD_FN_ACCOUNT, MD_SV_JSON, jacct, 0);
+    if (APR_SUCCESS == rv) {
+        rv = md_store_save(store, p, MD_SG_STAGING, md->name, MD_FN_ACCT_KEY, 
+                           MD_SV_PKEY, acme->acct_key, 0);
+    }
+    return rv;
+}
+
+apr_status_t md_acme_acct_save(md_store_t *store, apr_pool_t *p, md_acme_t *acme, 
+                               md_acme_acct_t *acct, md_pkey_t *acct_key)
+{
+    md_json_t *jacct;
+    apr_status_t rv;
+    int i;
+    const char *id;
+    
+    jacct = acct_to_json(acct, p);
+    id = acct->id;
+    
+    if (id) {
+        rv = md_store_save(store, p, MD_SG_ACCOUNTS, id, MD_FN_ACCOUNT, MD_SV_JSON, jacct, 0);
+    }
+    else {
+        rv = APR_EAGAIN;
+        for (i = 0; i < 1000 && APR_SUCCESS != rv; ++i) {
+            id = mk_acct_id(p, acme, i);
+            md_json_sets(id, jacct, MD_KEY_ID, NULL);
+            rv = md_store_save(store, p, MD_SG_ACCOUNTS, id, MD_FN_ACCOUNT, MD_SV_JSON, jacct, 1);
+        }
+        
+    }
+    if (APR_SUCCESS == rv) {
+        acct->id = id;
+        rv = md_store_save(store, p, MD_SG_ACCOUNTS, id, MD_FN_ACCT_KEY, MD_SV_PKEY, acct_key, 0);
+    }
+    return rv;
+}
+
+apr_status_t md_acme_save(md_acme_t *acme, md_store_t *store, apr_pool_t *p)
+{
+    return md_acme_acct_save(store, p, acme, acme->acct, acme->acct_key); 
+}
+
+apr_status_t md_acme_acct_load(md_acme_acct_t **pacct, md_pkey_t **ppkey,
+                               md_store_t *store, md_store_group_t group, 
+                               const char *name, apr_pool_t *p)
+{
+    md_json_t *json;
+    apr_status_t rv;
+
+    rv = md_store_load_json(store, group, name, MD_FN_ACCOUNT, &json, p);
+    if (APR_STATUS_IS_ENOENT(rv)) {
+        goto out;
+    }
+    if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "error reading account: %s", name);
+        goto out;
+    }
+    
+    rv = acct_from_json(pacct, json, p);
+    if (APR_SUCCESS == rv) {
+        rv = md_store_load(store, group, name, MD_FN_ACCT_KEY, MD_SV_PKEY, (void**)ppkey, p);
+        if (APR_SUCCESS != rv) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "loading key: %s", name);
+            goto out;
+        }
+    }
+out:
+    if (APR_SUCCESS != rv) {
+        *pacct = NULL;
+        *ppkey = NULL;
+    } 
+    return rv;
+}
+
+/**************************************************************************************************/
+/* Lookup */
+
+typedef struct {
+    apr_pool_t *p;
+    md_acme_t *acme;
+    const char *id;
+} find_ctx;
+
+static int find_acct(void *baton, const char *name, const char *aspect,
+                     md_store_vtype_t vtype, void *value, apr_pool_t *ptemp)
+{
+    find_ctx *ctx = baton;
+    md_json_t *json = value;
+    int disabled;
+    const char *ca_url, *id;
+    
+    id = md_json_gets(json, MD_KEY_ID, NULL);
+    disabled = md_json_getb(json, MD_KEY_DISABLED, NULL);
+    ca_url = md_json_gets(json, MD_KEY_CA_URL, NULL);
+    
+    if (!disabled && ca_url && !strcmp(ctx->acme->url, ca_url)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, ctx->p, 
+                      "found account %s for %s: %s, disabled=%d, ca-url=%s", 
+                      name, ctx->acme->url, id, disabled, ca_url);
+        ctx->id = id;
+        return 0;
+    }
+    return 1;
+}
+
+static apr_status_t acct_find(md_acme_acct_t **pacct, md_pkey_t **ppkey, 
+                              md_store_t *store, md_acme_t *acme, apr_pool_t *p)
+{
+    apr_status_t rv;
+    find_ctx ctx;
+    
+    ctx.p = p;
+    ctx.acme = acme;
+    ctx.id = NULL;
+    
+    rv = md_store_iter(find_acct, &ctx, store, p, MD_SG_ACCOUNTS, mk_acct_pattern(p, acme),
+                       MD_FN_ACCOUNT, MD_SV_JSON);
+    if (ctx.id) {
+        rv = md_acme_acct_load(pacct, ppkey, store, MD_SG_ACCOUNTS, ctx.id, p);
+    }
+    else {
+        *pacct = NULL;
+        rv = APR_ENOENT;
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                  "acct_find %s", (*pacct)? (*pacct)->id : "NULL"); 
+    return rv;
+}
+
+/**************************************************************************************************/
+/* Register a new account */
+
+typedef struct {
+    md_acme_t *acme;
+    apr_pool_t *p;
+} acct_ctx_t;
+
+static apr_status_t on_init_acct_new(md_acme_req_t *req, void *baton)
+{
+    acct_ctx_t *ctx = baton;
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("new-reg", jpayload, MD_KEY_RESOURCE, NULL);
+    md_json_setsa(ctx->acme->acct->contacts, jpayload, MD_KEY_CONTACT, NULL);
+    if (ctx->acme->acct->agreement) {
+        md_json_sets(ctx->acme->acct->agreement, jpayload, MD_KEY_AGREEMENT, NULL);
+    }
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t acct_upd(md_acme_t *acme, apr_pool_t *p, 
+                             const apr_table_t *hdrs, md_json_t *body, void *baton)
+{
+    acct_ctx_t *ctx = baton;
+    apr_status_t rv = APR_SUCCESS;
+    md_acme_acct_t *acct = acme->acct;
+    
+    if (!acct->url) {
+        const char *location = apr_table_get(hdrs, "location");
+        if (!location) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, APR_EINVAL, p, "new acct without location");
+            return APR_EINVAL;
+        }
+        acct->url = apr_pstrdup(ctx->p, location);
+    }
+    if (!acct->tos_required) {
+        acct->tos_required = md_link_find_relation(hdrs, ctx->p, "terms-of-service");
+        if (acct->tos_required) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, 
+                          "server requires agreement to <%s>", acct->tos_required);
+        }
+    }
+    
+    apr_array_clear(acct->contacts);
+    md_json_getsa(acct->contacts, body, MD_KEY_CONTACT, NULL);
+    acct->registration = md_json_clone(ctx->p, body);
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "updated acct %s", acct->url);
+    return rv;
+}
+
+static apr_status_t acct_register(md_acme_t *acme, apr_pool_t *p,  
+                                  apr_array_header_t *contacts, const char *agreement)
+{
+    apr_status_t rv;
+    md_pkey_t *pkey;
+    const char *err = NULL, *uri;
+    int i;
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "create new account");
+    
+    if (agreement) {
+        if (APR_SUCCESS != (rv = md_util_abs_uri_check(acme->p, agreement, &err))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, 
+                          "invalid agreement uri (%s): %s", err, agreement);
+            goto out;
+        }
+    }
+    for (i = 0; i < contacts->nelts; ++i) {
+        uri = APR_ARRAY_IDX(contacts, i, const char *);
+        if (APR_SUCCESS != (rv = md_util_abs_uri_check(acme->p, uri, &err))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, 
+                          "invalid contact uri (%s): %s", err, uri);
+            goto out;
+        }
+    }
+    
+    if (APR_SUCCESS == (rv = md_pkey_gen_rsa(&pkey, acme->p, acme->pkey_bits))
+        && APR_SUCCESS == (rv = acct_make(&acme->acct,  p, acme->url, NULL, contacts))) {
+        acct_ctx_t ctx;
+
+        acme->acct_key = pkey;
+        if (agreement) {
+            acme->acct->agreement = agreement;
+        }
+
+        ctx.acme = acme;
+        ctx.p = p;
+        rv = md_acme_POST(acme, acme->new_reg, on_init_acct_new, acct_upd, NULL, &ctx);
+        if (APR_SUCCESS == rv) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, p, 
+                          "registered new account %s", acme->acct->url);
+        }
+    }
+
+out:    
+    if (APR_SUCCESS != rv && acme->acct) {
+        md_acme_acct_free(acme->acct);
+        acme->acct = NULL;
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* acct validation */
+
+static apr_status_t on_init_acct_valid(md_acme_req_t *req, void *baton)
+{
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("reg", jpayload, MD_KEY_RESOURCE, NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t acct_valid(md_acme_t *acme, apr_pool_t *p, const apr_table_t *hdrs, 
+                               md_json_t *body, void *baton)
+{
+    md_acme_acct_t *acct = acme->acct;
+    apr_status_t rv = APR_SUCCESS;
+    const char *body_str;
+    const char *tos_required;
+    
+    apr_array_clear(acct->contacts);
+    md_json_getsa(acct->contacts, body, MD_KEY_CONTACT, NULL);
+    acct->registration = md_json_clone(acme->p, body);
+    
+    body_str = md_json_writep(body, acme->p, MD_JSON_FMT_INDENT);
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, acme->p, "validate acct %s: %s", 
+                  acct->url, body_str ? body_str : "<failed to serialize!>");
+    
+    acct->agreement = md_json_gets(acct->registration, MD_KEY_AGREEMENT, NULL);
+    tos_required = md_link_find_relation(hdrs, acme->p, "terms-of-service");
+    
+    if (tos_required) {
+        if (!acct->agreement || strcmp(tos_required, acct->agreement)) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, acme->p, 
+                          "needs to agree to terms-of-service '%s', "
+                          "has already agreed to '%s'", 
+                          tos_required, acct->agreement);
+        }
+        acct->tos_required = tos_required;
+    }
+    
+    return rv;
+}
+
+static apr_status_t md_acme_validate_acct(md_acme_t *acme)
+{
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, acme->p, "acct validation");
+    if (!acme->acct) {
+        return APR_EINVAL;
+    }
+    return md_acme_POST(acme, acme->acct->url, on_init_acct_valid, acct_valid, NULL, NULL);
+}
+
+/**************************************************************************************************/
+/* account setup */
+
+static apr_status_t acct_validate(md_acme_t *acme, md_store_t *store, apr_pool_t *p)
+{
+    apr_status_t rv;
+    
+    if (APR_SUCCESS != (rv = md_acme_validate_acct(acme))) {
+        if (acme->acct && (APR_ENOENT == rv || APR_EACCES == rv)) {
+            if (!acme->acct->disabled) {
+                acme->acct->disabled = 1;
+                if (store) {
+                    md_acme_save(acme, store, p);
+                }
+            }
+            acme->acct = NULL;
+            acme->acct_key = NULL;
+            rv = APR_ENOENT;
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_acme_use_acct(md_acme_t *acme, md_store_t *store,
+                              apr_pool_t *p, const char *acct_id)
+{
+    md_acme_acct_t *acct;
+    md_pkey_t *pkey;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = md_acme_acct_load(&acct, &pkey, 
+                                               store, MD_SG_ACCOUNTS, acct_id, acme->p))) {
+        if (acct->ca_url && !strcmp(acct->ca_url, acme->url)) {
+            acme->acct = acct;
+            acme->acct_key = pkey;
+            rv = acct_validate(acme, store, p);
+        }
+        else {
+            /* account is from a nother server or, more likely, from another
+             * protocol endpoint on the same server */
+            rv = APR_ENOENT;
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_acme_use_acct_staged(md_acme_t *acme, struct md_store_t *store, 
+                                     md_t *md, apr_pool_t *p)
+{
+    md_acme_acct_t *acct;
+    md_pkey_t *pkey;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = md_acme_acct_load(&acct, &pkey, 
+                                               store, MD_SG_STAGING, md->name, acme->p))) {
+        acme->acct = acct;
+        acme->acct_key = pkey;
+        rv = acct_validate(acme, NULL, p);
+    }
+    return rv;
+}
+
+const char *md_acme_get_acct(md_acme_t *acme, apr_pool_t *p)
+{
+    return acme->acct? acme->acct->id : NULL;
+}
+
+const char *md_acme_get_agreement(md_acme_t *acme)
+{
+    return acme->acct? acme->acct->agreement : NULL;
+}
+
+apr_status_t md_acme_find_acct(md_acme_t *acme, md_store_t *store, apr_pool_t *p)
+{
+    md_acme_acct_t *acct;
+    md_pkey_t *pkey;
+    apr_status_t rv;
+    
+    while (APR_SUCCESS == acct_find(&acct, &pkey, store, acme, acme->p)) {
+        acme->acct = acct;
+        acme->acct_key = pkey;
+        rv = acct_validate(acme, store, p);
+        
+        if (APR_SUCCESS == rv) {
+            return rv;
+        }
+        else {
+            acme->acct = NULL;
+            acme->acct_key = NULL;
+            if (!APR_STATUS_IS_ENOENT(rv)) {
+                /* encountered error with server */
+                return rv;
+            }
+        }
+    }
+    return APR_ENOENT;
+}
+
+apr_status_t md_acme_create_acct(md_acme_t *acme, apr_pool_t *p, apr_array_header_t *contacts, 
+                                 const char *agreement)
+{
+    return acct_register(acme, p, contacts, agreement);
+}
+
+/**************************************************************************************************/
+/* Delete the account */
+
+apr_status_t md_acme_unstore_acct(md_store_t *store, apr_pool_t *p, const char *acct_id) 
+{
+    apr_status_t rv = APR_SUCCESS;
+    
+    rv = md_store_remove(store, MD_SG_ACCOUNTS, acct_id, MD_FN_ACCOUNT, p, 1);
+    if (APR_SUCCESS == rv) {
+        md_store_remove(store, MD_SG_ACCOUNTS, acct_id, MD_FN_ACCT_KEY, p, 1);
+    }
+    return rv;
+}
+
+static apr_status_t on_init_acct_del(md_acme_req_t *req, void *baton)
+{
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("reg", jpayload, MD_KEY_RESOURCE, NULL);
+    md_json_setb(1, jpayload, "delete", NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t acct_del(md_acme_t *acme, apr_pool_t *p,
+                             const apr_table_t *hdrs, md_json_t *body, void *baton)
+{
+    md_store_t *store = baton;
+    apr_status_t rv = APR_SUCCESS;
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, p, "deleted account %s", acme->acct->url);
+    if (store) {
+        rv = md_acme_unstore_acct(store, p, acme->acct->id);
+        acme->acct = NULL;
+        acme->acct_key = NULL;
+    }
+    return rv;
+}
+
+apr_status_t md_acme_delete_acct(md_acme_t *acme, md_store_t *store, apr_pool_t *p)
+{
+    md_acme_acct_t *acct = acme->acct;
+    
+    if (!acct) {
+        return APR_EINVAL;
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, acme->p, "delete account %s from %s", 
+                  acct->url, acct->ca_url);
+    return md_acme_POST(acme, acct->url, on_init_acct_del, acct_del, NULL, store);
+}
+
+/**************************************************************************************************/
+/* terms-of-service */
+
+static apr_status_t on_init_agree_tos(md_acme_req_t *req, void *baton)
+{
+    acct_ctx_t *ctx = baton;
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("reg", jpayload, MD_KEY_RESOURCE, NULL);
+    md_json_sets(ctx->acme->acct->agreement, jpayload, MD_KEY_AGREEMENT, NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+apr_status_t md_acme_agree(md_acme_t *acme, apr_pool_t *p, const char *agreement)
+{
+    acct_ctx_t ctx;
+    
+    acme->acct->agreement = agreement;
+    ctx.acme = acme;
+    ctx.p = p;
+    return md_acme_POST(acme, acme->acct->url, on_init_agree_tos, acct_upd, NULL, &ctx);
+}
+
+static int agreement_required(md_acme_acct_t *acct)
+{
+    return (!acct->agreement 
+            || (acct->tos_required && strcmp(acct->tos_required, acct->agreement)));
+}
+
+apr_status_t md_acme_check_agreement(md_acme_t *acme, apr_pool_t *p, const char *agreement)
+{
+    apr_status_t rv = APR_SUCCESS;
+    
+    /* Check if (correct) Terms-of-Service for account were accepted */
+    if (agreement_required(acme->acct)) {
+        const char *tos = acme->acct->tos_required;
+        if (!tos) {
+            if (APR_SUCCESS != (rv = md_acme_validate_acct(acme))) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, acme->p, 
+                              "validate for account %", acme->acct->id); 
+                return rv;
+            }
+            tos = acme->acct->tos_required; 
+            if (!tos) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, acme->p, "unknown terms-of-service "
+                              "required after validation of account %", acme->acct->id); 
+                return APR_EGENERAL;
+            }
+        }
+        
+        if (acme->acct->agreement && !strcmp(tos, acme->acct->agreement)) {
+            rv = md_acme_agree(acme, p, tos);
+        }
+        else if (agreement && !strcmp(tos, agreement)) {
+            rv = md_acme_agree(acme, p, tos);
+        }
+        else {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, acme->p, 
+                          "need to accept terms-of-service <%s> for account %s", 
+                          tos, acme->acct->id);
+            rv = APR_EACCES;
+        }
+    }
+    return rv;
+}        
diff --git a/modules/md/md_acme_acct.h b/modules/md/md_acme_acct.h
new file mode 100644
index 0000000000..5abd9b5031
--- /dev/null
+++ b/modules/md/md_acme_acct.h
@@ -0,0 +1,44 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_acme_acct_h
+#define mod_md_md_acme_acct_h
+
+struct md_acme_req;
+struct md_json_t;
+struct md_pkey_t;
+
+
+/** 
+ * An ACME account at an ACME server.
+ */
+typedef struct md_acme_acct_t md_acme_acct_t;
+
+struct md_acme_acct_t {
+    const char *id;                 /* short, unique id for the account */
+    const char *url;                /* url of the account, once registered */
+    const char *ca_url;             /* url of the ACME protocol endpoint */
+    apr_array_header_t *contacts;   /* list of contact uris, e.g. mailto:xxx */
+    const char *tos_required;       /* terms of service asked for by CA */
+    const char *agreement;          /* terms of service agreed to by user */
+    
+    struct md_json_t *registration; /* data from server registration */
+    int disabled;
+};
+
+#define MD_FN_ACCOUNT           "account.json"
+#define MD_FN_ACCT_KEY          "account.pem"
+
+#endif /* md_acme_acct_h */
diff --git a/modules/md/md_acme_authz.c b/modules/md/md_acme_authz.c
new file mode 100644
index 0000000000..83c6ca9609
--- /dev/null
+++ b/modules/md/md_acme_authz.c
@@ -0,0 +1,682 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+
+#include <apr_lib.h>
+#include <apr_buckets.h>
+#include <apr_file_info.h>
+#include <apr_file_io.h>
+#include <apr_fnmatch.h>
+#include <apr_hash.h>
+#include <apr_strings.h>
+#include <apr_tables.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_json.h"
+#include "md_http.h"
+#include "md_log.h"
+#include "md_jws.h"
+#include "md_store.h"
+#include "md_util.h"
+
+#include "md_acme.h"
+#include "md_acme_authz.h"
+
+md_acme_authz_t *md_acme_authz_create(apr_pool_t *p)
+{
+    md_acme_authz_t *authz;
+    authz = apr_pcalloc(p, sizeof(*authz));
+    
+    return authz;
+}
+
+md_acme_authz_set_t *md_acme_authz_set_create(apr_pool_t *p, md_acme_t *acme)
+{
+    md_acme_authz_set_t *authz_set;
+    
+    authz_set = apr_pcalloc(p, sizeof(*authz_set));
+    authz_set->authzs = apr_array_make(p, 5, sizeof(md_acme_authz_t *));
+    
+    return authz_set;
+}
+
+md_acme_authz_t *md_acme_authz_set_get(md_acme_authz_set_t *set, const char *domain)
+{
+    md_acme_authz_t *authz;
+    int i;
+    
+    assert(domain);
+    for (i = 0; i < set->authzs->nelts; ++i) {
+        authz = APR_ARRAY_IDX(set->authzs, i, md_acme_authz_t *);
+        if (!apr_strnatcasecmp(domain, authz->domain)) {
+            return authz;
+        }
+    }
+    return NULL;
+}
+
+apr_status_t md_acme_authz_set_add(md_acme_authz_set_t *set, md_acme_authz_t *authz)
+{
+    md_acme_authz_t *existing;
+    
+    assert(authz->domain);
+    if (NULL != (existing = md_acme_authz_set_get(set, authz->domain))) {
+        return APR_EINVAL;
+    }
+    APR_ARRAY_PUSH(set->authzs, md_acme_authz_t*) = authz;
+    return APR_SUCCESS;
+}
+
+apr_status_t md_acme_authz_set_remove(md_acme_authz_set_t *set, const char *domain)
+{
+    md_acme_authz_t *authz;
+    int i;
+    
+    assert(domain);
+    for (i = 0; i < set->authzs->nelts; ++i) {
+        authz = APR_ARRAY_IDX(set->authzs, i, md_acme_authz_t *);
+        if (!apr_strnatcasecmp(domain, authz->domain)) {
+            int n = i +1;
+            if (n < set->authzs->nelts) {
+                void **elems = (void **)set->authzs->elts;
+                memmove(elems + i, elems + n, set->authzs->nelts - n); 
+            }
+            --set->authzs->nelts;
+            return APR_SUCCESS;
+        }
+    }
+    return APR_ENOENT;
+}
+
+/**************************************************************************************************/
+/* Register a new authorization */
+
+typedef struct {
+    size_t index;
+    const char *type;
+    const char *uri;
+    const char *token;
+    const char *key_authz;
+} md_acme_authz_cha_t;
+
+typedef struct {
+    apr_pool_t *p;
+    md_acme_t *acme;
+    const char *domain;
+    md_acme_authz_t *authz;
+    md_acme_authz_cha_t *challenge;
+} authz_req_ctx;
+
+static void authz_req_ctx_init(authz_req_ctx *ctx, md_acme_t *acme, 
+                               const char *domain, md_acme_authz_t *authz, apr_pool_t *p)
+{
+    memset(ctx, 0, sizeof(*ctx));
+    ctx->p = p;
+    ctx->acme = acme;
+    ctx->domain = domain;
+    ctx->authz = authz;
+}
+
+static apr_status_t on_init_authz(md_acme_req_t *req, void *baton)
+{
+    authz_req_ctx *ctx = baton;
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("new-authz", jpayload, MD_KEY_RESOURCE, NULL);
+    md_json_sets("dns", jpayload, MD_KEY_IDENTIFIER, MD_KEY_TYPE, NULL);
+    md_json_sets(ctx->domain, jpayload, MD_KEY_IDENTIFIER, MD_KEY_VALUE, NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t authz_created(md_acme_t *acme, apr_pool_t *p, const apr_table_t *hdrs, 
+                                  md_json_t *body, void *baton)
+{
+    authz_req_ctx *ctx = baton;
+    const char *location = apr_table_get(hdrs, "location");
+    apr_status_t rv = APR_SUCCESS;
+    
+    if (location) {
+        ctx->authz = md_acme_authz_create(ctx->p);
+        ctx->authz->domain = apr_pstrdup(ctx->p, ctx->domain);
+        ctx->authz->location = apr_pstrdup(ctx->p, location);
+        ctx->authz->resource = md_json_clone(ctx->p, body);
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, rv, ctx->p, "authz_new at %s", location);
+    }
+    else {
+        rv = APR_EINVAL;
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, ctx->p, "new authz, no location header");
+    }
+    return rv;
+}
+
+apr_status_t md_acme_authz_register(struct md_acme_authz_t **pauthz, md_acme_t *acme, 
+                                    md_store_t *store, const char *domain, apr_pool_t *p)
+{
+    apr_status_t rv;
+    authz_req_ctx ctx;
+    
+    authz_req_ctx_init(&ctx, acme, domain, NULL, p);
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, acme->p, "create new authz");
+    rv = md_acme_POST(acme, acme->new_authz, on_init_authz, authz_created, NULL, &ctx);
+    
+    *pauthz = (APR_SUCCESS == rv)? ctx.authz : NULL;
+    return rv;
+}
+
+/**************************************************************************************************/
+/* Update an exiosting authorization */
+
+apr_status_t md_acme_authz_update(md_acme_authz_t *authz, md_acme_t *acme, 
+                                  md_store_t *store, apr_pool_t *p)
+{
+    md_json_t *json;
+    const char *s;
+    apr_status_t rv;
+    
+    assert(acme);
+    assert(acme->http);
+    assert(authz);
+    assert(authz->location);
+
+    if (APR_SUCCESS != (rv = md_acme_get_json(&json, acme, authz->location, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "update authz for %s at %s",
+                      authz->domain, authz->location);
+        return rv;
+    }
+    
+    authz->resource = json;
+    s = md_json_gets(json, "identifier", "type", NULL);
+    if (!s || strcmp(s, "dns")) return APR_EINVAL;
+    s = md_json_gets(json, "identifier", "value", NULL);
+    if (!s || strcmp(s, authz->domain)) return APR_EINVAL;
+    
+    authz->state = MD_ACME_AUTHZ_S_UNKNOWN;
+    s = md_json_gets(json, "status", NULL);
+    if (s && !strcmp(s, "pending")) {
+        authz->state = MD_ACME_AUTHZ_S_PENDING;
+    }
+    else if (s && !strcmp(s, "valid")) {
+        authz->state = MD_ACME_AUTHZ_S_VALID;
+    }
+    else if (s && !strcmp(s, "invalid")) {
+        authz->state = MD_ACME_AUTHZ_S_INVALID;
+    }
+    else if (s) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, p, "unknown authz state '%s' "
+                      "for %s in %s", s, authz->domain, authz->location);
+        return APR_EINVAL;
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* response to a challenge */
+
+static md_acme_authz_cha_t *cha_from_json(apr_pool_t *p, size_t index, md_json_t *json)
+{
+    md_acme_authz_cha_t * cha;
+    
+    cha = apr_pcalloc(p, sizeof(*cha));
+    cha->index = index;
+    cha->type = md_json_dups(p, json, MD_KEY_TYPE, NULL);
+    cha->uri = md_json_dups(p, json, MD_KEY_URI, NULL);
+    cha->token = md_json_dups(p, json, MD_KEY_TOKEN, NULL);
+    cha->key_authz = md_json_dups(p, json, MD_KEY_KEYAUTHZ, NULL);
+
+    return cha;
+}
+
+static apr_status_t on_init_authz_resp(md_acme_req_t *req, void *baton)
+{
+    authz_req_ctx *ctx = baton;
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("challenge", jpayload, MD_KEY_RESOURCE, NULL);
+    md_json_sets(ctx->challenge->key_authz, jpayload, MD_KEY_KEYAUTHZ, NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t authz_http_set(md_acme_t *acme, apr_pool_t *p, const apr_table_t *hdrs, 
+                                   md_json_t *body, void *baton)
+{
+    authz_req_ctx *ctx = baton;
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, ctx->p, "updated authz %s", ctx->authz->location);
+    return APR_SUCCESS;
+}
+
+static apr_status_t setup_key_authz(md_acme_authz_cha_t *cha, md_acme_authz_t *authz,
+                                    md_acme_t *acme, apr_pool_t *p, int *pchanged)
+{
+    const char *thumb64, *key_authz;
+    apr_status_t rv;
+    
+    assert(cha);
+    assert(cha->token);
+    
+    *pchanged = 0;
+    if (APR_SUCCESS == (rv = md_jws_pkey_thumb(&thumb64, p, acme->acct_key))) {
+        key_authz = apr_psprintf(p, "%s.%s", cha->token, thumb64);
+        if (cha->key_authz) {
+            if (strcmp(key_authz, cha->key_authz)) {
+                /* Hu? Did the account change key? */
+                cha->key_authz = NULL;
+            }
+        }
+        if (!cha->key_authz) {
+            cha->key_authz = key_authz;
+            *pchanged = 1;
+        }
+    }
+    return rv;
+}
+
+static apr_status_t cha_http_01_setup(md_acme_authz_cha_t *cha, md_acme_authz_t *authz, 
+                                      md_acme_t *acme, md_store_t *store, apr_pool_t *p)
+{
+    const char *data;
+    apr_status_t rv;
+    int notify_server;
+    
+    if (APR_SUCCESS != (rv = setup_key_authz(cha, authz, acme, p, &notify_server))) {
+        goto out;
+    }
+    
+    rv = md_store_load(store, MD_SG_CHALLENGES, authz->domain, MD_FN_HTTP01,
+                       MD_SV_TEXT, (void**)&data, p);
+    if ((APR_SUCCESS == rv && strcmp(cha->key_authz, data)) || APR_STATUS_IS_ENOENT(rv)) {
+        rv = md_store_save(store, p, MD_SG_CHALLENGES, authz->domain, MD_FN_HTTP01,
+                           MD_SV_TEXT, (void*)cha->key_authz, 0);
+        authz->dir = authz->domain;
+        notify_server = 1;
+    }
+    
+    if (APR_SUCCESS == rv && notify_server) {
+        authz_req_ctx ctx;
+
+        /* challenge is setup or was changed from previous data, tell ACME server
+         * so it may (re)try verification */        
+        authz_req_ctx_init(&ctx, acme, NULL, authz, p);
+        ctx.challenge = cha;
+        rv = md_acme_POST(acme, cha->uri, on_init_authz_resp, authz_http_set, NULL, &ctx);
+    }
+out:
+    return rv;
+}
+
+static apr_status_t setup_cha_dns(const char **pdns, md_acme_authz_cha_t *cha, apr_pool_t *p)
+{
+    const char *dhex;
+    char *dns;
+    apr_size_t dhex_len;
+    apr_status_t rv;
+    
+    rv = md_crypt_sha256_digest_hex(&dhex, p, cha->key_authz, strlen(cha->key_authz));
+    if (APR_SUCCESS == rv) {
+        dhex = md_util_str_tolower((char*)dhex);
+        dhex_len = strlen(dhex); 
+        assert(dhex_len > 32);
+        dns = apr_pcalloc(p, dhex_len + 1 + sizeof(MD_TLSSNI01_DNS_SUFFIX));
+        strncpy(dns, dhex, 32);
+        dns[32] = '.';
+        strncpy(dns+33, dhex+32, dhex_len-32);
+        memcpy(dns+(dhex_len+1), MD_TLSSNI01_DNS_SUFFIX, sizeof(MD_TLSSNI01_DNS_SUFFIX));
+    }
+    *pdns = (APR_SUCCESS == rv)? dns : NULL;
+    return rv;
+}
+
+static apr_status_t cha_tls_sni_01_setup(md_acme_authz_cha_t *cha, md_acme_authz_t *authz, 
+                                         md_acme_t *acme, md_store_t *store, apr_pool_t *p)
+{
+    md_cert_t *cha_cert;
+    md_pkey_t *cha_key;
+    const char *cha_dns;
+    apr_status_t rv;
+    int notify_server;
+    
+    if (   APR_SUCCESS != (rv = setup_key_authz(cha, authz, acme, p, &notify_server))
+        || APR_SUCCESS != (rv = setup_cha_dns(&cha_dns, cha, p))) {
+        goto out;
+    }
+
+    rv = md_store_load(store, MD_SG_CHALLENGES, cha_dns, MD_FN_TLSSNI01_CERT,
+                       MD_SV_CERT, (void**)&cha_cert, p);
+    if ((APR_SUCCESS == rv && !md_cert_covers_domain(cha_cert, cha_dns)) 
+        || APR_STATUS_IS_ENOENT(rv)) {
+        
+        if (APR_SUCCESS != (rv = md_pkey_gen_rsa(&cha_key, p, acme->pkey_bits))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: create tls-sni-01 challgenge key",
+                          authz->domain);
+            goto out;
+        }
+
+        /* setup a certificate containing the challenge dns */
+        rv = md_cert_self_sign(&cha_cert, authz->domain, cha_dns, cha_key, 
+                               apr_time_from_sec(7 * MD_SECS_PER_DAY), p);
+        
+        if (APR_SUCCESS != rv) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: setup self signed cert for %s",
+                          authz->domain, cha_dns);
+            goto out;
+        }
+        
+        rv = md_store_save(store, p, MD_SG_CHALLENGES, cha_dns, MD_FN_TLSSNI01_PKEY,
+                           MD_SV_PKEY, (void*)cha_key, 0);
+        if (APR_SUCCESS == rv) {
+            rv = md_store_save(store, p, MD_SG_CHALLENGES, cha_dns, MD_FN_TLSSNI01_CERT,
+                               MD_SV_CERT, (void*)cha_cert, 0);
+        }
+        authz->dir = cha_dns;
+        notify_server = 1;
+    }
+    
+    if (APR_SUCCESS == rv && notify_server) {
+        authz_req_ctx ctx;
+
+        /* challenge is setup or was changed from previous data, tell ACME server
+         * so it may (re)try verification */        
+        authz_req_ctx_init(&ctx, acme, NULL, authz, p);
+        ctx.challenge = cha;
+        rv = md_acme_POST(acme, cha->uri, on_init_authz_resp, authz_http_set, NULL, &ctx);
+    }
+out:    
+    return rv;
+}
+
+typedef apr_status_t cha_starter(md_acme_authz_cha_t *cha, md_acme_authz_t *authz, 
+                                 md_acme_t *acme, md_store_t *store, apr_pool_t *p);
+                                 
+typedef struct {
+    const char *name;
+    cha_starter *start;
+} cha_type;
+
+static const cha_type CHA_TYPES[] = {
+    { MD_AUTHZ_TYPE_HTTP01,     cha_http_01_setup },
+    { MD_AUTHZ_TYPE_TLSSNI01,   cha_tls_sni_01_setup },
+};
+static const apr_size_t CHA_TYPES_LEN = (sizeof(CHA_TYPES)/sizeof(CHA_TYPES[0]));
+
+typedef struct {
+    apr_pool_t *p;
+    const char *type;
+    md_acme_authz_cha_t *accepted;
+    apr_array_header_t *offered;
+} cha_find_ctx;
+
+static apr_status_t collect_offered(void *baton, size_t index, md_json_t *json)
+{
+    cha_find_ctx *ctx = baton;
+    
+    const char *ctype = md_json_gets(json, MD_KEY_TYPE, NULL);
+    if (ctype) {
+        APR_ARRAY_PUSH(ctx->offered, const char*) = apr_pstrdup(ctx->p, ctype);
+    }
+    return 1;
+}
+
+static apr_status_t find_type(void *baton, size_t index, md_json_t *json)
+{
+    cha_find_ctx *ctx = baton;
+    
+    const char *ctype = md_json_gets(json, MD_KEY_TYPE, NULL);
+    if (ctype && !apr_strnatcasecmp(ctx->type, ctype)) {
+        ctx->accepted = cha_from_json(ctx->p, index, json);
+        return 0;
+    }
+    return 1;
+}
+
+apr_status_t md_acme_authz_respond(md_acme_authz_t *authz, md_acme_t *acme, md_store_t *store, 
+                                   apr_array_header_t *challenges, apr_pool_t *p)
+{
+    apr_status_t rv;
+    int i;
+    cha_find_ctx fctx;
+    
+    assert(acme);
+    assert(authz);
+    assert(authz->resource);
+
+    fctx.p = p;
+    fctx.accepted = NULL;
+    
+    /* Look in the order challenge types are defined */
+    for (i = 0; i < challenges->nelts && !fctx.accepted; ++i) {
+        fctx.type = APR_ARRAY_IDX(challenges, i, const char *);
+        md_json_itera(find_type, &fctx, authz->resource, MD_KEY_CHALLENGES, NULL);
+    }
+    
+    if (!fctx.accepted) {
+        rv = APR_EINVAL;
+        fctx.offered = apr_array_make(p, 5, sizeof(const char*));
+        md_json_itera(collect_offered, &fctx, authz->resource, MD_KEY_CHALLENGES, NULL);
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, 
+                      "%s: the server offers no ACME challenge that is configured "
+                      "for this MD. The server offered '%s' and available for this "
+                      "MD are: '%s' (via %s).",
+                      authz->domain, 
+                      apr_array_pstrcat(p, fctx.offered, ' '),
+                      apr_array_pstrcat(p, challenges, ' '),
+                      authz->location);
+        return rv;
+    }
+    
+    for (i = 0; i < CHA_TYPES_LEN; ++i) {
+        if (!apr_strnatcasecmp(CHA_TYPES[i].name, fctx.accepted->type)) {
+            return CHA_TYPES[i].start(fctx.accepted, authz, acme, store, p);
+        }
+    }
+    
+    rv = APR_ENOTIMPL;
+    md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, 
+                  "%s: no implementation found for challenge '%s'",
+                  authz->domain, fctx.accepted->type);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* Delete an existing authz resource */
+
+typedef struct {
+    apr_pool_t *p;
+    md_acme_authz_t *authz;
+} del_ctx;
+
+static apr_status_t on_init_authz_del(md_acme_req_t *req, void *baton)
+{
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("deactivated", jpayload, MD_KEY_STATUS, NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t authz_del(md_acme_t *acme, apr_pool_t *p, const apr_table_t *hdrs, 
+                              md_json_t *body, void *baton)
+{
+    authz_req_ctx *ctx = baton;
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, ctx->p, "deleted authz %s", ctx->authz->location);
+    acme->acct = NULL;
+    return APR_SUCCESS;
+}
+
+apr_status_t md_acme_authz_del(md_acme_authz_t *authz, md_acme_t *acme, 
+                               md_store_t *store, apr_pool_t *p)
+{
+    authz_req_ctx ctx;
+    
+    ctx.p = p;
+    ctx.authz = authz;
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "delete authz for %s from %s", 
+                  authz->domain, authz->location);
+    return md_acme_POST(acme, authz->location, on_init_authz_del, authz_del, NULL, &ctx);
+}
+
+/**************************************************************************************************/
+/* authz conversion */
+
+md_json_t *md_acme_authz_to_json(md_acme_authz_t *a, apr_pool_t *p)
+{
+    md_json_t *json = md_json_create(p);
+    if (json) {
+        md_json_sets(a->domain, json, MD_KEY_DOMAIN, NULL);
+        md_json_sets(a->location, json, MD_KEY_LOCATION, NULL);
+        md_json_sets(a->dir, json, MD_KEY_DIR, NULL);
+        md_json_setl(a->state, json, MD_KEY_STATE, NULL);
+        return json;
+    }
+    return NULL;
+}
+
+md_acme_authz_t *md_acme_authz_from_json(struct md_json_t *json, apr_pool_t *p)
+{
+    md_acme_authz_t *authz = md_acme_authz_create(p);
+    if (authz) {
+        authz->domain = md_json_dups(p, json, MD_KEY_DOMAIN, NULL);            
+        authz->location = md_json_dups(p, json, MD_KEY_LOCATION, NULL);            
+        authz->dir = md_json_dups(p, json, MD_KEY_DIR, NULL);            
+        authz->state = (int)md_json_getl(json, MD_KEY_STATE, NULL);            
+        return authz;
+    }
+    return NULL;
+}
+
+/**************************************************************************************************/
+/* authz_set conversion */
+
+#define MD_KEY_ACCOUNT          "account"
+#define MD_KEY_AUTHZS           "authorizations"
+
+static apr_status_t authz_to_json(void *value, md_json_t *json, apr_pool_t *p, void *baton)
+{
+    return md_json_setj(md_acme_authz_to_json(value, p), json, NULL);
+}
+
+static apr_status_t authz_from_json(void **pvalue, md_json_t *json, apr_pool_t *p, void *baton)
+{
+    *pvalue = md_acme_authz_from_json(json, p);
+    return (*pvalue)? APR_SUCCESS : APR_EINVAL;
+}
+
+md_json_t *md_acme_authz_set_to_json(md_acme_authz_set_t *set, apr_pool_t *p)
+{
+    md_json_t *json = md_json_create(p);
+    if (json) {
+        md_json_seta(set->authzs, authz_to_json, NULL, json, MD_KEY_AUTHZS, NULL);
+        return json;
+    }
+    return NULL;
+}
+
+md_acme_authz_set_t *md_acme_authz_set_from_json(md_json_t *json, apr_pool_t *p)
+{
+    md_acme_authz_set_t *set = md_acme_authz_set_create(p, NULL);
+    if (set) {
+        md_json_geta(set->authzs, authz_from_json, NULL, json, MD_KEY_AUTHZS, NULL);
+        return set;
+    }
+    return NULL;
+}
+
+/**************************************************************************************************/
+/* persistence */
+
+apr_status_t md_acme_authz_set_load(struct md_store_t *store, md_store_group_t group, 
+                                    const char *md_name, md_acme_authz_set_t **pauthz_set, 
+                                    apr_pool_t *p)
+{
+    apr_status_t rv;
+    md_json_t *json;
+    md_acme_authz_set_t *authz_set;
+    
+    rv = md_store_load_json(store, group, md_name, MD_FN_AUTHZ, &json, p);
+    if (APR_SUCCESS == rv) {
+        authz_set = md_acme_authz_set_from_json(json, p);
+    }
+    *pauthz_set = (APR_SUCCESS == rv)? authz_set : NULL;
+    return rv;  
+}
+
+static apr_status_t p_save(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_t *store = baton;
+    md_json_t *json;
+    md_store_group_t group;
+    md_acme_authz_set_t *set;
+    const char *md_name;
+    int create;
+    
+    group = va_arg(ap, int);
+    md_name = va_arg(ap, const char *);
+    set = va_arg(ap, md_acme_authz_set_t *);
+    create = va_arg(ap, int);
+
+    json = md_acme_authz_set_to_json(set, ptemp);
+    assert(json);
+    return md_store_save_json(store, ptemp, group, md_name, MD_FN_AUTHZ, json, create);
+}
+
+apr_status_t md_acme_authz_set_save(struct md_store_t *store, apr_pool_t *p,
+                                    md_store_group_t group, const char *md_name, 
+                                    md_acme_authz_set_t *authz_set, int create)
+{
+    return md_util_pool_vdo(p_save, store, p, group, md_name, authz_set, create, NULL);
+}
+
+static apr_status_t p_purge(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_t *store = baton;
+    md_acme_authz_set_t *authz_set;
+    const md_acme_authz_t *authz;
+    md_store_group_t group;
+    const char *md_name;
+    int i;
+
+    group = va_arg(ap, int);
+    md_name = va_arg(ap, const char *);
+
+    if (APR_SUCCESS == md_acme_authz_set_load(store, group, md_name, &authz_set, p)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "authz_set loaded for %s", md_name);
+        for (i = 0; i < authz_set->authzs->nelts; ++i) {
+            authz = APR_ARRAY_IDX(authz_set->authzs, i, const md_acme_authz_t*);
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "authz check %s", authz->domain);
+            if (authz->dir) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "authz purge %s", authz->dir);
+                md_store_purge(store, p, MD_SG_CHALLENGES, authz->dir);
+            }
+        }
+    }
+    return md_store_remove(store, group, md_name, MD_FN_AUTHZ, ptemp, 1);
+}
+
+apr_status_t md_acme_authz_set_purge(md_store_t *store, md_store_group_t group,
+                                     apr_pool_t *p, const char *md_name)
+{
+    return md_util_pool_vdo(p_purge, store, p, group, md_name, NULL);
+}
+
diff --git a/modules/md/md_acme_authz.h b/modules/md/md_acme_authz.h
new file mode 100644
index 0000000000..0996deb56b
--- /dev/null
+++ b/modules/md/md_acme_authz.h
@@ -0,0 +1,102 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_acme_authz_h
+#define mod_md_md_acme_authz_h
+
+struct apr_array_header_t;
+struct md_acme_t;
+struct md_acme_acct_t;
+struct md_json_t;
+struct md_store_t;
+
+typedef struct md_acme_challenge_t md_acme_challenge_t;
+
+/**************************************************************************************************/
+/* authorization request for a specific domain name */
+
+#define MD_AUTHZ_TYPE_HTTP01        "http-01"
+#define MD_AUTHZ_TYPE_TLSSNI01      "tls-sni-01"
+
+typedef enum {
+    MD_ACME_AUTHZ_S_UNKNOWN,
+    MD_ACME_AUTHZ_S_PENDING,
+    MD_ACME_AUTHZ_S_VALID,
+    MD_ACME_AUTHZ_S_INVALID,
+} md_acme_authz_state_t;
+
+typedef struct md_acme_authz_t md_acme_authz_t;
+
+struct md_acme_authz_t {
+    const char *domain;
+    const char *location;
+    const char *dir;
+    md_acme_authz_state_t state;
+    apr_time_t expires;
+    struct md_json_t *resource;
+};
+
+#define MD_FN_HTTP01            "acme-http-01.txt"
+#define MD_FN_TLSSNI01_CERT     "acme-tls-sni-01.cert.pem"
+#define MD_FN_TLSSNI01_PKEY     "acme-tls-sni-01.key.pem"
+#define MD_FN_AUTHZ             "authz.json"
+
+
+md_acme_authz_t *md_acme_authz_create(apr_pool_t *p);
+
+struct md_json_t *md_acme_authz_to_json(md_acme_authz_t *a, apr_pool_t *p);
+md_acme_authz_t *md_acme_authz_from_json(struct md_json_t *json, apr_pool_t *p);
+
+/* authz interaction with ACME server */
+apr_status_t md_acme_authz_register(struct md_acme_authz_t **pauthz, struct md_acme_t *acme,
+                                    struct md_store_t *store, const char *domain, apr_pool_t *p);
+
+apr_status_t md_acme_authz_update(md_acme_authz_t *authz, struct md_acme_t *acme, 
+                                  struct md_store_t *store, apr_pool_t *p);
+
+apr_status_t md_acme_authz_respond(md_acme_authz_t *authz, struct md_acme_t *acme, 
+                                   struct md_store_t *store, 
+                                   apr_array_header_t *challenges, apr_pool_t *p);
+apr_status_t md_acme_authz_del(md_acme_authz_t *authz, struct md_acme_t *acme, 
+                               struct md_store_t *store, apr_pool_t *p);
+
+/**************************************************************************************************/
+/* set of authz data for a managed domain */
+
+typedef struct md_acme_authz_set_t md_acme_authz_set_t;
+
+struct md_acme_authz_set_t {
+    struct apr_array_header_t *authzs;
+};
+
+md_acme_authz_set_t *md_acme_authz_set_create(apr_pool_t *p, struct md_acme_t *acme);
+md_acme_authz_t *md_acme_authz_set_get(md_acme_authz_set_t *set, const char *domain);
+apr_status_t md_acme_authz_set_add(md_acme_authz_set_t *set, md_acme_authz_t *authz);
+apr_status_t md_acme_authz_set_remove(md_acme_authz_set_t *set, const char *domain);
+
+struct md_json_t *md_acme_authz_set_to_json(md_acme_authz_set_t *set, apr_pool_t *p);
+md_acme_authz_set_t *md_acme_authz_set_from_json(struct md_json_t *json, apr_pool_t *p);
+
+apr_status_t md_acme_authz_set_load(struct md_store_t *store, md_store_group_t group, 
+                                    const char *md_name, md_acme_authz_set_t **pauthz_set, 
+                                    apr_pool_t *p);
+apr_status_t md_acme_authz_set_save(struct md_store_t *store, apr_pool_t *p, 
+                                    md_store_group_t group, const char *md_name, 
+                                    md_acme_authz_set_t *authz_set, int create);
+
+apr_status_t md_acme_authz_set_purge(struct md_store_t *store, md_store_group_t group,
+                                     apr_pool_t *p, const char *md_name);
+
+#endif /* md_acme_authz_h */
diff --git a/modules/md/md_acme_drive.c b/modules/md/md_acme_drive.c
new file mode 100644
index 0000000000..f72e6bd730
--- /dev/null
+++ b/modules/md/md_acme_drive.c
@@ -0,0 +1,926 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_buckets.h>
+#include <apr_hash.h>
+#include <apr_uri.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_json.h"
+#include "md_jws.h"
+#include "md_http.h"
+#include "md_log.h"
+#include "md_reg.h"
+#include "md_store.h"
+#include "md_util.h"
+
+#include "md_acme.h"
+#include "md_acme_acct.h"
+#include "md_acme_authz.h"
+
+typedef struct {
+    md_proto_driver_t *driver;
+    
+    const char *phase;
+    int complete;
+
+    md_pkey_t *pkey;
+    md_cert_t *cert;
+    apr_array_header_t *chain;
+
+    md_acme_t *acme;
+    md_t *md;
+    const md_creds_t *ncreds;
+    
+    apr_array_header_t *ca_challenges;
+    md_acme_authz_set_t *authz_set;
+    apr_interval_time_t authz_monitor_timeout;
+    
+    const char *csr_der_64;
+    apr_interval_time_t cert_poll_timeout;
+    
+    const char *chain_url;
+    
+} md_acme_driver_t;
+
+/**************************************************************************************************/
+/* account setup */
+
+static apr_status_t ad_set_acct(md_proto_driver_t *d) 
+{
+    md_acme_driver_t *ad = d->baton;
+    md_t *md = ad->md;
+    apr_status_t rv = APR_SUCCESS;
+    int update = 0, acct_installed = 0;
+    
+    ad->phase = "setup acme";
+    if (!ad->acme 
+        && APR_SUCCESS != (rv = md_acme_create(&ad->acme, d->p, md->ca_url))) {
+        goto out;
+    }
+
+    ad->phase = "choose account";
+    /* Do we have a staged (modified) account? */
+    if (APR_SUCCESS == (rv = md_acme_use_acct_staged(ad->acme, d->store, md, d->p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "re-using staged account");
+        md->ca_account = MD_ACME_ACCT_STAGED;
+        acct_installed = 1;
+    }
+    else if (APR_STATUS_IS_ENOENT(rv)) {
+        rv = APR_SUCCESS;
+    }
+    
+    /* Get an account for the ACME server for this MD */
+    if (md->ca_account && !acct_installed) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "re-use account '%s'", md->ca_account);
+        rv = md_acme_use_acct(ad->acme, d->store, d->p, md->ca_account);
+        if (APR_STATUS_IS_ENOENT(rv) || APR_STATUS_IS_EINVAL(rv)) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "rejected %s", md->ca_account);
+            md->ca_account = NULL;
+            update = 1;
+            rv = APR_SUCCESS;
+        }
+    }
+
+    if (APR_SUCCESS == rv && !md->ca_account) {
+        /* Find a local account for server, store at MD */ 
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: looking at existing accounts",
+                      d->proto->protocol);
+        if (APR_SUCCESS == md_acme_find_acct(ad->acme, d->store, d->p)) {
+            md->ca_account = md_acme_get_acct(ad->acme, d->p);
+            update = 1;
+        }
+    }
+    
+    if (APR_SUCCESS == rv && !md->ca_account) {
+        /* 2.2 No local account exists, create a new one */
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: creating new account", 
+                      d->proto->protocol);
+        
+        if (!ad->md->contacts || apr_is_empty_array(md->contacts)) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, d->p, 
+                          "no contact information for md %s", md->name);            
+            rv = APR_EINVAL;
+            goto out;
+        }
+    
+        if (APR_SUCCESS == (rv = md_acme_create_acct(ad->acme, d->p, 
+                                                     md->contacts, md->ca_agreement))
+            && APR_SUCCESS == (rv = md_acme_acct_save_staged(ad->acme, d->store, md, d->p))) {
+            md->ca_account = MD_ACME_ACCT_STAGED;
+            update = 1;
+        }
+    }
+    
+out:
+    if (APR_SUCCESS == rv) {
+        const char *agreement = md_acme_get_agreement(ad->acme);
+        /* Persist the account chosen at the md so we use the same on future runs */
+        if (agreement && (!md->ca_agreement || strcmp(agreement, md->ca_agreement))) { 
+            md->ca_agreement = agreement;
+            update = 1;
+        }
+        if (update) {
+            rv = md_save(d->store, d->p, MD_SG_STAGING, ad->md, 0);
+        }
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* authz/challenge setup */
+
+/**
+ * Pre-Req: we have an account for the ACME server that has accepted the current license agreement
+ * For each domain in MD: 
+ * - check if there already is a valid AUTHZ resource
+ * - if ot, create an AUTHZ resource with challenge data 
+ */
+static apr_status_t ad_setup_authz(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv;
+    md_t *md = ad->md;
+    md_acme_authz_t *authz;
+    int i, changed;
+    
+    assert(ad->md);
+    assert(ad->acme);
+
+    ad->phase = "check authz";
+    
+    /* For each domain in MD: AUTHZ setup
+     * if an AUTHZ resource is known, check if it is still valid
+     * if known AUTHZ resource is not valid, remove, goto 4.1.1
+     * if no AUTHZ available, create a new one for the domain, store it
+     */
+    rv = md_acme_authz_set_load(d->store, MD_SG_STAGING, md->name, &ad->authz_set, d->p);
+    if (!ad->authz_set || APR_STATUS_IS_ENOENT(rv)) {
+        ad->authz_set = md_acme_authz_set_create(d->p, ad->acme);
+        rv = APR_SUCCESS;
+    }
+    else if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: loading authz data", md->name);
+        md_acme_authz_set_purge(d->store, MD_SG_STAGING, d->p, md->name);
+        return APR_EAGAIN;
+    }
+    
+    /* Remove anything we no longer need */
+    for (i = 0; i < ad->authz_set->authzs->nelts; ++i) {
+        authz = APR_ARRAY_IDX(ad->authz_set->authzs, i, md_acme_authz_t*);
+        if (!md_contains(md, authz->domain)) {
+            md_acme_authz_set_remove(ad->authz_set, authz->domain);
+            changed = 1;
+        }
+    }
+    
+    /* Add anything we do not already have */
+    for (i = 0; i < md->domains->nelts && APR_SUCCESS == rv; ++i) {
+        const char *domain = APR_ARRAY_IDX(md->domains, i, const char *);
+        changed = 0;
+        authz = md_acme_authz_set_get(ad->authz_set, domain);
+        if (authz) {
+            /* check valid */
+            rv = md_acme_authz_update(authz, ad->acme, d->store, d->p);
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: updated authz for %s", 
+                          md->name, domain);
+            if (APR_SUCCESS != rv) {
+                md_acme_authz_set_remove(ad->authz_set, domain);
+                authz = NULL;
+                changed = 1;
+            }
+        }
+        if (!authz) {
+            /* create new one */
+            rv = md_acme_authz_register(&authz, ad->acme, d->store, domain, d->p);
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: created authz for %s", 
+                          md->name, domain);
+            if (APR_SUCCESS == rv) {
+                rv = md_acme_authz_set_add(ad->authz_set, authz);
+                changed = 1;
+            }
+        }
+    }
+    
+    /* Save any changes */
+    if (APR_SUCCESS == rv && changed) {
+        rv = md_acme_authz_set_save(d->store, d->p, MD_SG_STAGING, md->name, ad->authz_set, 0);
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, rv, d->p, "%s: saved", md->name);
+    }
+    
+    return rv;
+}
+
+/**
+ * Pre-Req: all domains have a AUTHZ resources at the ACME server
+ * For each domain in MD: 
+ * - if AUTHZ resource is 'valid' -> continue
+ * - if AUTHZ resource is 'pending':
+ *   - find preferred challenge choice
+ *   - calculate challenge data for httpd to find
+ *   - POST challenge start to ACME server
+ * For each domain in MD where AUTHZ is 'pending', until overall timeout: 
+ *   - wait a certain time, check status again
+ * If not all AUTHZ are valid, fail
+ */
+static apr_status_t ad_start_challenges(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv = APR_SUCCESS;
+    md_acme_authz_t *authz;
+    int i, changed = 0;
+    
+    assert(ad->md);
+    assert(ad->acme);
+    assert(ad->authz_set);
+
+    ad->phase = "start challenges";
+
+    for (i = 0; i < ad->authz_set->authzs->nelts && APR_SUCCESS == rv; ++i) {
+        authz = APR_ARRAY_IDX(ad->authz_set->authzs, i, md_acme_authz_t*);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: check AUTHZ for %s", 
+                      ad->md->name, authz->domain);
+        if (APR_SUCCESS != (rv = md_acme_authz_update(authz, ad->acme, d->store, d->p))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, d->p, "%s: check authz for %s",
+                          ad->md->name, authz->domain);
+            break;
+        }
+
+        switch (authz->state) {
+            case MD_ACME_AUTHZ_S_VALID:
+                break;
+            case MD_ACME_AUTHZ_S_PENDING:
+                
+                rv = md_acme_authz_respond(authz, ad->acme, d->store, ad->ca_challenges, d->p);
+                changed = 1;
+                break;
+            default:
+                rv = APR_EINVAL;
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, d->p, 
+                              "%s: unexpected AUTHZ state %d at %s", 
+                              authz->domain, authz->state, authz->location);
+                break;
+        }
+    }
+    
+    if (APR_SUCCESS == rv && changed) {
+        rv = md_acme_authz_set_save(d->store, d->p, MD_SG_STAGING, ad->md->name, ad->authz_set, 0);
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, rv, d->p, "%s: saved", ad->md->name);
+    }
+    return rv;
+}
+
+static apr_status_t check_challenges(void *baton, int attemmpt)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    md_acme_authz_t *authz;
+    apr_status_t rv = APR_SUCCESS;
+    int i;
+    
+    for (i = 0; i < ad->authz_set->authzs->nelts && APR_SUCCESS == rv; ++i) {
+        authz = APR_ARRAY_IDX(ad->authz_set->authzs, i, md_acme_authz_t*);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: check AUTHZ for %s", 
+                      ad->md->name, authz->domain);
+        if (APR_SUCCESS == (rv = md_acme_authz_update(authz, ad->acme, d->store, d->p))) {
+            switch (authz->state) {
+                case MD_ACME_AUTHZ_S_VALID:
+                    break;
+                case MD_ACME_AUTHZ_S_PENDING:
+                    rv = APR_EAGAIN;
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, 
+                                  "%s: status pending at %s", authz->domain, authz->location);
+                    break;
+                default:
+                    rv = APR_EINVAL;
+                    md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, d->p, 
+                                  "%s: unexpected AUTHZ state %d at %s", 
+                                  authz->domain, authz->state, authz->location);
+                    break;
+            }
+        }
+    }
+    return rv;
+}
+
+static apr_status_t ad_monitor_challenges(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv;
+    
+    assert(ad->md);
+    assert(ad->acme);
+    assert(ad->authz_set);
+
+    ad->phase = "monitor challenges";
+    rv = md_util_try(check_challenges, d, 0, ad->authz_monitor_timeout, 0, 0, 1);
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_INFO, rv, d->p, 
+                  "%s: checked all domain authorizations", ad->md->name);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* poll cert */
+
+
+static apr_status_t read_http_cert(md_cert_t **pcert, apr_pool_t *p,
+                                   const md_http_response_t *res)
+{
+    apr_status_t rv = APR_SUCCESS;
+    
+    if (APR_SUCCESS != (rv = md_cert_read_http(pcert, p, res))
+        && APR_STATUS_IS_ENOENT(rv)) {
+        rv = APR_EAGAIN;
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                      "cert not in response from %s", res->req->url);
+    }
+    return rv;
+}
+
+static apr_status_t on_got_cert(md_acme_t *acme, const md_http_response_t *res, void *baton)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv = APR_SUCCESS;
+    
+    
+    if (APR_SUCCESS == (rv = read_http_cert(&ad->cert, d->p, res))) {
+        rv = md_store_save(d->store, d->p, MD_SG_STAGING, ad->md->name, MD_FN_CERT, 
+                           MD_SV_CERT, ad->cert, 0);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "cert parsed and saved");
+    }
+    return rv;
+}
+
+static apr_status_t get_cert(void *baton, int attempt)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    
+    return md_acme_GET(ad->acme, ad->md->cert_url, NULL, NULL, on_got_cert, d);
+}
+
+static apr_status_t ad_cert_poll(md_proto_driver_t *d, int only_once)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv;
+    
+    assert(ad->md);
+    assert(ad->acme);
+    assert(ad->md->cert_url);
+    
+    ad->phase = "poll certificate";
+    if (only_once) {
+        rv = get_cert(d, 0);
+    }
+    else {
+        rv = md_util_try(get_cert, d, 1, ad->cert_poll_timeout, 0, 0, 1);
+    }
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, "poll for cert at %s", ad->md->cert_url);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* cert setup */
+
+static apr_status_t on_init_csr_req(md_acme_req_t *req, void *baton)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    md_json_t *jpayload;
+
+    jpayload = md_json_create(req->p);
+    md_json_sets("new-cert", jpayload, MD_KEY_RESOURCE, NULL);
+    md_json_sets(ad->csr_der_64, jpayload, MD_KEY_CSR, NULL);
+    
+    return md_acme_req_body_init(req, jpayload);
+} 
+
+static apr_status_t csr_req(md_acme_t *acme, const md_http_response_t *res, void *baton)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv = APR_SUCCESS;
+    
+    ad->md->cert_url = apr_table_get(res->headers, "location");
+    if (!ad->md->cert_url) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, d->p, 
+                      "cert created without giving its location header");
+        return APR_EINVAL;
+    }
+    if (APR_SUCCESS != (rv = md_save(d->store, d->p, MD_SG_STAGING, ad->md, 0))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, d->p, 
+                      "%s: saving cert url %s", ad->md->name, ad->md->cert_url);
+        return rv;
+    }
+    
+    /* Check if it already was sent with this response */
+    if (APR_SUCCESS == (rv = md_cert_read_http(&ad->cert, d->p, res))) {
+        rv = md_cert_save(d->store, d->p, MD_SG_STAGING, ad->md->name, ad->cert, 0);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "cert parsed and saved");
+    }
+    else if (APR_STATUS_IS_ENOENT(rv)) {
+        rv = APR_SUCCESS;
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, 
+                      "cert not in response, need to poll %s", ad->md->cert_url);
+    }
+    
+    return rv;
+}
+
+/**
+ * Pre-Req: all domains have been validated by the ACME server, e.g. all have AUTHZ
+ * resources that have status 'valid'
+ * - Setup private key, if not already there
+ * - Generate a CSR with org, contact, etc
+ * - Optionally enable must-staple OCSP extension
+ * - Submit CSR, expect 201 with location
+ * - POLL location for certificate
+ * - store certificate
+ * - retrieve cert chain information from cert
+ * - GET cert chain
+ * - store cert chain
+ */
+static apr_status_t ad_setup_certificate(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    md_pkey_t *pkey;
+    apr_status_t rv;
+
+    ad->phase = "setup cert pkey";
+    
+    rv = md_pkey_load(d->store, MD_SG_STAGING, ad->md->name, &pkey, d->p);
+    if (APR_STATUS_IS_ENOENT(rv)) {
+        if (APR_SUCCESS == (rv = md_pkey_gen_rsa(&pkey, d->p, ad->acme->pkey_bits))) {
+            rv = md_pkey_save(d->store, d->p, MD_SG_STAGING, ad->md->name, pkey, 1);
+        }
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: generate pkey", ad->md->name);
+    }
+
+    if (APR_SUCCESS == rv) {
+        ad->phase = "setup csr";
+        rv = md_cert_req_create(&ad->csr_der_64, ad->md, pkey, d->p);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: create CSR", ad->md->name);
+    }
+
+    if (APR_SUCCESS == rv) {
+        ad->phase = "submit csr";
+        rv = md_acme_POST(ad->acme, ad->acme->new_cert, on_init_csr_req, NULL, csr_req, d);
+    }
+
+    if (APR_SUCCESS == rv) {
+        if (!ad->cert) {
+            rv = ad_cert_poll(d, 0);
+        }
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* cert chain retrieval */
+
+static apr_status_t on_add_chain(md_acme_t *acme, const md_http_response_t *res, void *baton)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv = APR_SUCCESS;
+    md_cert_t *cert;
+    const char *ct;
+    
+    ct = apr_table_get(res->headers, "Content-Type");
+    if (ct && !strcmp("application/x-pkcs7-mime", ct)) {
+        /* root cert most likely, end it here */
+        return APR_SUCCESS;
+    }
+    
+    if (APR_SUCCESS == (rv = read_http_cert(&cert, d->p, res))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "chain cert parsed");
+        APR_ARRAY_PUSH(ad->chain, md_cert_t *) = cert;
+    }
+    return rv;
+}
+
+static apr_status_t get_chain(void *baton, int attempt)
+{
+    md_proto_driver_t *d = baton;
+    md_acme_driver_t *ad = d->baton;
+    md_cert_t *cert;
+    const char *url, *last_url = NULL;
+    apr_status_t rv = APR_SUCCESS;
+    
+    while (APR_SUCCESS == rv && ad->chain->nelts < 10) {
+        int nelts = ad->chain->nelts;
+        if (ad->chain && nelts > 0) {
+            cert = APR_ARRAY_IDX(ad->chain, nelts - 1, md_cert_t *);
+        }
+        else {
+            cert = ad->cert;
+        }
+        
+        if (APR_SUCCESS == (rv = md_cert_get_issuers_uri(&url, cert, d->p))
+            && (!last_url || strcmp(last_url, url))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "next issuer is  %s", url);
+#if MD_EXPERIMENTAL
+            if (!strncmp("http://127.0.0.1:", url, sizeof("http://127.0.0.1:")-1)) {
+                /* test boulder instance always reports issuer cert on localhost, but we
+                 * may use a different address to reach the boulder server */
+                apr_uri_t curi, ca;
+                
+                if (APR_SUCCESS == apr_uri_parse(d->p, url, &curi)
+                    && APR_SUCCESS == apr_uri_parse(d->p, ad->acme->url, &ca)) {
+                    url = apr_psprintf(d->p, "%s://%s:%s%s", 
+                                       ca.scheme, ca.hostname, ca.port_str, curi.path);
+                }
+            }
+#endif
+            rv = md_acme_GET(ad->acme, url, NULL, NULL, on_add_chain, d);
+            
+            if (APR_SUCCESS == rv && nelts == ad->chain->nelts) {
+                break;
+            }
+        }
+        else if (APR_STATUS_IS_ENOENT(rv) || !url || !strlen(url)) {
+            rv = APR_SUCCESS;
+            break;
+        }
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, rv, d->p, 
+                  "got chain with %d certs", ad->chain->nelts);
+    return rv;
+}
+
+static apr_status_t ad_chain_install(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv;
+    
+    ad->chain = apr_array_make(d->p, 5, sizeof(md_cert_t *));
+    if (APR_SUCCESS == (rv = md_util_try(get_chain, d, 0, ad->cert_poll_timeout, 0, 0, 0))) {
+        rv = md_store_save(d->store, d->p, MD_SG_STAGING, ad->md->name, MD_FN_CHAIN, 
+                           MD_SV_CHAIN, ad->chain, 0);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "chain fetched and saved");
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* ACME driver init */
+
+static apr_status_t acme_driver_init(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad;
+    apr_status_t rv;
+
+    ad = apr_pcalloc(d->p, sizeof(*ad));
+    
+    d->baton = ad;
+    ad->driver = d;
+    
+    ad->authz_monitor_timeout = apr_time_from_sec(30);
+    ad->cert_poll_timeout = apr_time_from_sec(30);
+
+    /* We can only support challenges if the server is reachable from the outside
+     * via port 80 and/or 443. These ports might be mapped for httpd to something
+     * else, but a mapping needs to exist. */
+    ad->ca_challenges = apr_array_make(d->p, 3, sizeof(const char *)); 
+    if (d->challenge) {
+        /* we have been told to use this type */
+        APR_ARRAY_PUSH(ad->ca_challenges, const char*) = apr_pstrdup(d->p, d->challenge);
+    }
+    else if (d->md->ca_challenges && d->md->ca_challenges->nelts > 0) {
+        /* pre-configured set for this managed domain */
+        apr_array_cat(ad->ca_challenges, d->md->ca_challenges);
+    }
+    else {
+        /* free to chose. Add all we support and see what we get offered */
+        APR_ARRAY_PUSH(ad->ca_challenges, const char*) = MD_AUTHZ_TYPE_TLSSNI01;
+        APR_ARRAY_PUSH(ad->ca_challenges, const char*) = MD_AUTHZ_TYPE_HTTP01;
+    }
+    
+    if (!d->can_http && !d->can_https) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, d->p, "%s: the server seems neither "
+                      "reachable via http (port 80) nor https (port 443). The ACME protocol "
+                      "needs at least one of those so the CA can talk to the server and verify "
+                      "a domain ownership.", d->md->name);
+        return APR_EGENERAL;
+    }
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, d->p, "%s: init driver", d->md->name);
+    
+    rv = md_load(d->store, MD_SG_STAGING, d->md->name, &ad->md, d->p);
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, rv, d->p, "%s: checked stage md", d->md->name);
+    if (d->reset || APR_STATUS_IS_ENOENT(rv)) {
+        /* reset the staging area for this domain */
+        rv = md_store_purge(d->store, d->p, MD_SG_STAGING, d->md->name);
+        if (APR_SUCCESS != rv && !APR_STATUS_IS_ENOENT(rv)) {
+            return rv;
+        }
+        rv = APR_SUCCESS;
+    }
+    
+    if (ad->md) {
+        /* staging in progress.
+         * There are certain md properties that are updated in staging, others are only
+         * updated in the domains store. Are these still the same? If not, we better
+         * start anew.
+         */
+        if (strcmp(d->md->ca_url, ad->md->ca_url)
+            || strcmp(d->md->ca_proto, ad->md->ca_proto)) {
+            /* reject staging info in this case */
+            ad->md = NULL;
+            return APR_SUCCESS;
+        }
+        
+        if (d->md->ca_agreement 
+            && (!ad->md->ca_agreement || strcmp(d->md->ca_agreement, ad->md->ca_agreement))) {
+            ad->md->ca_agreement = d->md->ca_agreement;
+        }
+        
+        /* look for new ACME account information collected there */
+        rv = md_reg_creds_get(&ad->ncreds, d->reg, MD_SG_STAGING, d->md, d->p);
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: checked creds", d->md->name);
+        if (APR_STATUS_IS_ENOENT(rv)) {
+            rv = APR_SUCCESS;
+        }
+    }
+    
+    return rv;
+}
+
+/**************************************************************************************************/
+/* ACME staging */
+
+static apr_status_t acme_stage(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv = APR_SUCCESS;
+    int renew = 1;
+
+    if (md_log_is_level(d->p, MD_LOG_DEBUG)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, d->p, "%s: staging started, "
+                      "state=%d, can_http=%d, can_https=%d, challenges='%s'",
+                      d->md->name, d->md->state, d->can_http, d->can_https,
+                      apr_array_pstrcat(d->p, ad->ca_challenges, ' '));
+    }
+
+    /* Find out where we're at with this managed domain */
+    if (ad->ncreds && ad->ncreds->pkey && ad->ncreds->cert && ad->ncreds->chain) {
+        /* There is a full set staged, to be loaded */
+        md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, "%s: all data staged", d->md->name);
+        renew = 0;
+    }
+    
+    if (renew) {
+        if (APR_SUCCESS != (rv = md_acme_create(&ad->acme, d->p, d->md->ca_url)) 
+            || APR_SUCCESS != (rv = md_acme_setup(ad->acme))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, d->p, "%s: setup ACME(%s)", 
+                          d->md->name, d->md->ca_url);
+            return rv;
+        }
+
+        if (!ad->md) {
+            /* re-initialize staging */
+            md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, "%s: setup staging", d->md->name);
+            md_store_purge(d->store, d->p, MD_SG_STAGING, d->md->name);
+            ad->md = md_copy(d->p, d->md);
+            ad->md->cert_url = NULL; /* do not retrieve the old cert */
+            rv = md_save(d->store, d->p, MD_SG_STAGING, ad->md, 0);
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: save staged md", 
+                          ad->md->name);
+        }
+
+        if (APR_SUCCESS == rv && !ad->cert) {
+            md_cert_load(d->store, MD_SG_STAGING, ad->md->name, &ad->cert, d->p);
+        }
+
+        if (APR_SUCCESS == rv && !ad->cert) {
+            ad->phase = "get certificate";
+            md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, "%s: need certificate", d->md->name);
+            
+            /* Chose (or create) and ACME account to use */
+            rv = ad_set_acct(d);
+            
+            /* Check that the account agreed to the terms-of-service, otherwise
+             * requests for new authorizations are denied. ToS may change during the
+             * lifetime of an account */
+            if (APR_SUCCESS == rv) {
+                ad->phase = "check agreement";
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: check Terms-of-Service agreement", d->md->name);
+                
+                rv = md_acme_check_agreement(ad->acme, d->p, ad->md->ca_agreement);
+            }
+            
+            /* If we know a cert's location, try to get it. Previous download might
+             * have failed. If server 404 it, we clear our memory of it. */
+            if (APR_SUCCESS == rv && ad->md->cert_url) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: polling certificate", d->md->name);
+                rv = ad_cert_poll(d, 1);
+                if (APR_STATUS_IS_ENOENT(rv)) {
+                    /* Server reports to know nothing about it. */
+                    ad->md->cert_url = NULL;
+                    rv = md_reg_update(d->reg, d->p, ad->md->name, ad->md, MD_UPD_CERT_URL);
+                }
+            }
+            
+            if (APR_SUCCESS == rv && !ad->cert) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: setup new authorization", d->md->name);
+                if (APR_SUCCESS != (rv = ad_setup_authz(d))) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: setup authz resource", 
+                                  ad->md->name);
+                    goto out;
+                }
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: setup new challenges", d->md->name);
+                if (APR_SUCCESS != (rv = ad_start_challenges(d))) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: start challenges", 
+                                  ad->md->name);
+                    goto out;
+                }
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: monitoring challenge status", d->md->name);
+                if (APR_SUCCESS != (rv = ad_monitor_challenges(d))) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: monitor challenges", 
+                                  ad->md->name);
+                    goto out;
+                }
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: creating certificate request", d->md->name);
+                if (APR_SUCCESS != (rv = ad_setup_certificate(d))) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: setup certificate", 
+                                  ad->md->name);
+                    goto out;
+                }
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                              "%s: received certificate", d->md->name);
+            }
+            
+        }
+        
+        if (APR_SUCCESS == rv && !ad->chain) {
+            ad->phase = "install chain";
+            md_log_perror(MD_LOG_MARK, MD_LOG_INFO, 0, d->p, 
+                          "%s: retrieving certificate chain", d->md->name);
+            rv = ad_chain_install(d);
+        }
+    }
+out:    
+    return rv;
+}
+
+static apr_status_t acme_driver_stage(md_proto_driver_t *d)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv;
+
+    ad->phase = "ACME staging";
+    if (APR_SUCCESS == (rv = acme_stage(d))) {
+        ad->phase = "staging done";
+    }
+        
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: %s, %s", 
+                  d->md->name, d->proto->protocol, ad->phase);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* ACME preload */
+
+static apr_status_t acme_preload(md_store_t *store, md_store_group_t load_group, 
+                                 const char *name, apr_pool_t *p) 
+{
+    apr_status_t rv;
+    md_pkey_t *pkey, *acct_key;
+    md_t *md;
+    md_cert_t *cert;
+    apr_array_header_t *chain;
+    struct md_acme_acct_t *acct;
+
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, p, "%s: preload start", name);
+    /* Load all data which will be taken into the DOMAIN storage group.
+     * This serves several purposes:
+     *  1. It's a format check on the input data. 
+     *  2. We write back what we read, creating data with our own access permissions
+     *  3. We ignore any other accumulated data in STAGING
+     *  4. Once TMP is verified, we can swap/archive groups with a rename
+     *  5. Reading/Writing the data will apply/remove any group specific data encryption.
+     *     With the exemption that DOMAINS and TMP must apply the same policy/keys.
+     */
+    if (APR_SUCCESS != (rv = md_load(store, MD_SG_STAGING, name, &md, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "%s: loading md json", name);
+        return rv;
+    }
+    if (APR_SUCCESS != (rv = md_cert_load(store, MD_SG_STAGING, name, &cert, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "%s: loading certificate", name);
+        return rv;
+    }
+    if (APR_SUCCESS != (rv = md_chain_load(store, MD_SG_STAGING, name, &chain, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "%s: loading cert chain", name);
+        return rv;
+    }
+    if (APR_SUCCESS != (rv = md_pkey_load(store, MD_SG_STAGING, name, &pkey, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "%s: loading staging private key", name);
+        return rv;
+    }
+
+    /* See if staging holds a new or modified account data */
+    rv = md_acme_acct_load(&acct, &acct_key, store, MD_SG_STAGING, name, p);
+    if (APR_STATUS_IS_ENOENT(rv)) {
+        acct = NULL;
+        acct_key = NULL;
+        rv = APR_SUCCESS;
+    }
+    else if (APR_SUCCESS != rv) {
+        return rv; 
+    }
+
+    /* Remove any authz information we have here or in MD_SG_CHALLENGES */
+    md_acme_authz_set_purge(store, MD_SG_STAGING, p, name);
+
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                  "%s: staged data load, purging tmp space", name);
+    rv = md_store_purge(store, p, load_group, name);
+    if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: error purging preload storage", name);
+        return rv;
+    }
+    
+    if (acct) {
+        md_acme_t *acme;
+        
+        if (APR_SUCCESS != (rv = md_acme_create(&acme, p, md->ca_url))
+            || APR_SUCCESS != (rv = md_acme_acct_save(store, p, acme, acct, acct_key))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: error saving acct", name);
+            return rv;
+        }
+        md->ca_account = acct->id;
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "%s: saved ACME account %s", 
+                      name, acct->id);
+    }
+    
+    if (APR_SUCCESS != (rv = md_save(store, p, load_group, md, 1))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: saving md json", name);
+        return rv;
+    }
+    if (APR_SUCCESS != (rv = md_cert_save(store, p, load_group, name, cert, 1))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: saving certificate", name);
+        return rv;
+    }
+    if (APR_SUCCESS != (rv = md_chain_save(store, p, load_group, name, chain, 1))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: saving cert chain", name);
+        return rv;
+    }
+    if (APR_SUCCESS != (rv = md_pkey_save(store, p, load_group, name, pkey, 1))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: saving domain private key", name);
+        return rv;
+    }
+    
+    return rv;
+}
+
+static apr_status_t acme_driver_preload(md_proto_driver_t *d, md_store_group_t group)
+{
+    md_acme_driver_t *ad = d->baton;
+    apr_status_t rv;
+
+    ad->phase = "ACME preload";
+    if (APR_SUCCESS == (rv = acme_preload(d->store, group, d->md->name, d->p))) {
+        ad->phase = "preload done";
+    }
+        
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, d->p, "%s: %s, %s", 
+                  d->md->name, d->proto->protocol, ad->phase);
+    return rv;
+}
+
+static md_proto_t ACME_PROTO = {
+    MD_PROTO_ACME, acme_driver_init, acme_driver_stage, acme_driver_preload
+};
+ 
+apr_status_t md_acme_protos_add(apr_hash_t *protos, apr_pool_t *p)
+{
+    apr_hash_set(protos, MD_PROTO_ACME, sizeof(MD_PROTO_ACME)-1, &ACME_PROTO);
+    return APR_SUCCESS;
+}
diff --git a/modules/md/md_config.c b/modules/md/md_config.c
new file mode 100644
index 0000000000..5a31255372
--- /dev/null
+++ b/modules/md/md_config.c
@@ -0,0 +1,583 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+
+#include <httpd.h>
+#include <http_core.h>
+#include <http_config.h>
+#include <http_log.h>
+#include <http_vhost.h>
+
+#include "md.h"
+#include "md_config.h"
+#include "md_util.h"
+
+extern module AP_MODULE_DECLARE_DATA md_module;
+APLOG_USE_MODULE(md);
+
+#define DEF_VAL     (-1)
+
+static md_config_t defconf = {
+    "default",
+    NULL,
+    80,
+    443,
+    NULL,
+    MD_ACME_DEF_URL,
+    "ACME",
+    NULL, 
+    NULL,
+    MD_DRIVE_AUTO,
+    apr_time_from_sec(14 * MD_SECS_PER_DAY), 
+    NULL, 
+    "md",
+    NULL
+};
+
+#define CONF_S_NAME(s)  (s && s->server_hostname? s->server_hostname : "default")
+
+void *md_config_create_svr(apr_pool_t *pool, server_rec *s)
+{
+    md_config_t *conf = (md_config_t *)apr_pcalloc(pool, sizeof(md_config_t));
+
+    conf->name = apr_pstrcat(pool, "srv[", CONF_S_NAME(s), "]", NULL);
+    conf->s = s;
+    conf->local_80 = DEF_VAL;
+    conf->local_443 = DEF_VAL;
+    conf->drive_mode = DEF_VAL;
+    conf->mds = apr_array_make(pool, 5, sizeof(const md_t *));
+    conf->renew_window = DEF_VAL;
+    
+    return conf;
+}
+
+static void *md_config_merge(apr_pool_t *pool, void *basev, void *addv)
+{
+    md_config_t *base = (md_config_t *)basev;
+    md_config_t *add = (md_config_t *)addv;
+    md_config_t *n = (md_config_t *)apr_pcalloc(pool, sizeof(md_config_t));
+    char *name = apr_pstrcat(pool, "[", CONF_S_NAME(add->s), ", ", CONF_S_NAME(base->s), "]", NULL);
+    md_t *md;
+    int i;
+    
+    n->name = name;
+    n->local_80 = (add->local_80 != DEF_VAL)? add->local_80 : base->local_80;
+    n->local_443 = (add->local_443 != DEF_VAL)? add->local_443 : base->local_443;
+
+    /* I think we should not merge md definitions. They should reside where
+     * they were defined */
+    n->mds = apr_array_make(pool, add->mds->nelts, sizeof(const md_t *));
+    for (i = 0; i < add->mds->nelts; ++i) {
+        md = APR_ARRAY_IDX(add->mds, i, md_t*);
+        APR_ARRAY_PUSH(n->mds, md_t *) = md_clone(pool, md);
+    }
+    n->ca_url = add->ca_url? add->ca_url : base->ca_url;
+    n->ca_proto = add->ca_proto? add->ca_proto : base->ca_proto;
+    n->ca_agreement = add->ca_agreement? add->ca_agreement : base->ca_agreement;
+    n->drive_mode = (add->drive_mode != DEF_VAL)? add->drive_mode : base->drive_mode;
+    n->md = NULL;
+    n->base_dir = add->base_dir? add->base_dir : base->base_dir;
+    n->renew_window = (add->renew_window != DEF_VAL)? add->renew_window : base->renew_window;
+    n->ca_challenges = (add->ca_challenges? apr_array_copy(pool, add->ca_challenges) 
+                    : (base->ca_challenges? apr_array_copy(pool, base->ca_challenges) : NULL));
+    return n;
+}
+
+void *md_config_merge_svr(apr_pool_t *pool, void *basev, void *addv)
+{
+    return md_config_merge(pool, basev, addv);
+}
+
+void *md_config_create_dir(apr_pool_t *pool, char *dummy)
+{
+    md_config_dir_t *conf = apr_pcalloc(pool, sizeof(*conf));
+    return conf;
+}
+
+void *md_config_merge_dir(apr_pool_t *pool, void *basev, void *addv)
+{
+    md_config_dir_t *base = basev;
+    md_config_dir_t *add = addv;
+    md_config_dir_t *n = apr_pcalloc(pool, sizeof(*n));
+    n->md = add->md? add->md : base->md;
+    return n;
+}
+
+static int inside_section(cmd_parms *cmd) {
+    return (cmd->directive->parent 
+            && !ap_cstr_casecmp(cmd->directive->parent->directive, "<ManagedDomain"));
+}
+
+static const char *md_section_check(cmd_parms *cmd) {
+    if (!inside_section(cmd)) {
+        return apr_pstrcat(cmd->pool, cmd->cmd->name, 
+                           " is only valid inside a <ManagedDomain context, not ", 
+                           cmd->directive->parent? cmd->directive->parent->directive : "root", 
+                           NULL);
+    }
+    return NULL;
+}
+
+static void add_domain_name(apr_array_header_t *domains, const char *name, apr_pool_t *p)
+{
+    if (md_array_str_index(domains, name, 0, 0) < 0) {
+        APR_ARRAY_PUSH(domains, char *) = md_util_str_tolower(apr_pstrdup(p, name));
+    }
+}
+
+static const char *md_config_sec_start(cmd_parms *cmd, void *mconfig, const char *arg)
+{
+    md_config_t *sconf = ap_get_module_config(cmd->server->module_config, &md_module);
+    const char *endp = ap_strrchr_c(arg, '>');
+    ap_conf_vector_t *new_dir_conf = ap_create_per_dir_config(cmd->pool);
+    int old_overrides = cmd->override;
+    char *old_path = cmd->path;
+    const char *err, *name;
+    md_config_dir_t *dconf;
+    md_t *md;
+
+    if (NULL != (err = ap_check_cmd_context(cmd, NOT_IN_DIR_LOC_FILE))) {
+        return err;
+    }
+        
+    if (endp == NULL) {
+        return apr_pstrcat(cmd->pool, cmd->cmd->name, "> directive missing closing '>'", NULL);
+    }
+
+    arg = apr_pstrndup(cmd->pool, arg, endp-arg);
+    if (!arg || !*arg) {
+        return "<ManagedDomain > block must specify a unique domain name";
+    }
+
+    cmd->path = ap_getword_white(cmd->pool, &arg);
+    name = cmd->path;
+    
+    md = md_create_empty(cmd->pool);
+    md->name = name;
+    APR_ARRAY_PUSH(md->domains, const char*) = name;
+    md->drive_mode = DEF_VAL;
+    
+    while (*arg != '\0') {
+        name = ap_getword_white(cmd->pool, &arg);
+        APR_ARRAY_PUSH(md->domains, const char*) = name;
+    }
+
+    dconf = ap_set_config_vectors(cmd->server, new_dir_conf, cmd->path, &md_module, cmd->pool);
+    dconf->md = md;
+    
+    if (NULL == (err = ap_walk_config(cmd->directive->first_child, cmd, new_dir_conf))) {
+        APR_ARRAY_PUSH(sconf->mds, const md_t *) = md;
+    }
+    
+    cmd->path = old_path;
+    cmd->override = old_overrides;
+
+    return err;
+}
+
+static const char *md_config_sec_add_members(cmd_parms *cmd, void *dc, 
+                                             int argc, char *const argv[])
+{
+    md_config_dir_t *dconfig = dc;
+    apr_array_header_t *domains;
+    const char *err;
+    int i;
+    
+    if (NULL != (err = md_section_check(cmd))) {
+        return err;
+    }
+    
+    domains = dconfig->md->domains;
+    for (i = 0; i < argc; ++i) {
+        add_domain_name(domains, argv[i], cmd->pool);
+    }
+    return NULL;
+}
+
+static const char *md_config_set_names(cmd_parms *cmd, void *arg, 
+                                       int argc, char *const argv[])
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    apr_array_header_t *domains = apr_array_make(cmd->pool, 5, sizeof(const char *));
+    const char *err;
+    md_t *md;
+    int i;
+
+    err = ap_check_cmd_context(cmd, NOT_IN_DIR_LOC_FILE);
+    if (err) {
+        return err;
+    }
+
+    for (i = 0; i < argc; ++i) {
+        add_domain_name(domains, argv[i], cmd->pool);
+    }
+    err = md_create(&md, cmd->pool, domains);
+    if (err) {
+        return err;
+    }
+    
+    if (cmd->config_file) {
+        md->defn_name = cmd->config_file->name;
+        md->defn_line_number = cmd->config_file->line_number;
+    }
+
+    APR_ARRAY_PUSH(config->mds, md_t *) = md;
+
+    return NULL;
+}
+
+static const char *md_config_set_ca(cmd_parms *cmd, void *dc, const char *value)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err;
+
+    if (inside_section(cmd)) {
+        md_config_dir_t *dconf = dc;
+        dconf->md->ca_url = value;
+    }
+    else {
+        if ((err = ap_check_cmd_context(cmd, GLOBAL_ONLY))) {
+            return err;
+        }
+        config->ca_url = value;
+    }
+    return NULL;
+}
+
+static const char *md_config_set_ca_proto(cmd_parms *cmd, void *dc, const char *value)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err;
+
+    if (inside_section(cmd)) {
+        md_config_dir_t *dconf = dc;
+        dconf->md->ca_proto = value;
+    }
+    else {
+        if ((err = ap_check_cmd_context(cmd, GLOBAL_ONLY))) {
+            return err;
+        }
+        config->ca_proto = value;
+    }
+    return NULL;
+}
+
+static const char *md_config_set_agreement(cmd_parms *cmd, void *dc, const char *value)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err;
+
+    if (inside_section(cmd)) {
+        md_config_dir_t *dconf = dc;
+        dconf->md->ca_agreement = value;
+    }
+    else {
+        if ((err = ap_check_cmd_context(cmd, GLOBAL_ONLY))) {
+            return err;
+        }
+        config->ca_agreement = value;
+    }
+    return NULL;
+}
+
+static const char *md_config_set_drive_mode(cmd_parms *cmd, void *dc, const char *value)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err;
+    md_drive_mode_t drive_mode;
+
+    if (!apr_strnatcasecmp("auto", value) || !apr_strnatcasecmp("automatic", value)) {
+        drive_mode = MD_DRIVE_AUTO;
+    }
+    else if (!apr_strnatcasecmp("always", value)) {
+        drive_mode = MD_DRIVE_ALWAYS;
+    }
+    else if (!apr_strnatcasecmp("manual", value) || !apr_strnatcasecmp("stick", value)) {
+        drive_mode = MD_DRIVE_MANUAL;
+    }
+    else {
+        return apr_pstrcat(cmd->pool, "unknown MDDriveMode ", value, NULL);
+    }
+    
+    if (inside_section(cmd)) {
+        md_config_dir_t *dconf = dc;
+        dconf->md->drive_mode = drive_mode;
+    }
+    else {
+        if ((err = ap_check_cmd_context(cmd, GLOBAL_ONLY))) {
+            return err;
+        }
+        config->drive_mode = drive_mode;
+    }
+    return NULL;
+}
+
+static apr_status_t duration_parse(const char *value, apr_interval_time_t *ptimeout, 
+                                   const char *def_unit)
+{
+    char *endp;
+    long funits = 1;
+    apr_status_t rv;
+    apr_int64_t n;
+    
+    n = apr_strtoi64(value, &endp, 10);
+    if (errno) {
+        return errno;
+    }
+    if (!endp || !*endp) {
+        if (strcmp(def_unit, "d") == 0) {
+            def_unit = "s";
+            funits = MD_SECS_PER_DAY;
+        }
+    }
+    else if (*endp == 'd') {
+        *ptimeout = apr_time_from_sec(n * MD_SECS_PER_DAY);
+        return APR_SUCCESS;
+    }
+    else {
+        def_unit = endp;
+    }
+    rv = ap_timeout_parameter_parse(value, ptimeout, def_unit);
+    if (APR_SUCCESS == rv && funits > 1) {
+        *ptimeout *= funits;
+    }
+    return rv;
+}
+
+static const char *md_config_set_renew_window(cmd_parms *cmd, void *dc, const char *value)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err;
+    apr_interval_time_t timeout;
+
+    /* Inspired by http_core.c */
+    if (duration_parse(value, &timeout, "d") != APR_SUCCESS) {
+        return "MDRenewWindow has wrong format";
+    }
+        
+    if (inside_section(cmd)) {
+        md_config_dir_t *dconf = dc;
+        dconf->md->renew_window = timeout;
+    }
+    else {
+        if ((err = ap_check_cmd_context(cmd, GLOBAL_ONLY))) {
+            return err;
+        }
+        config->renew_window = timeout;
+    }
+    return NULL;
+}
+
+static const char *md_config_set_store_dir(cmd_parms *cmd, void *arg, const char *value)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
+
+    if (err) {
+        return err;
+    }
+    config->base_dir = value;
+    (void)arg;
+    return NULL;
+}
+
+static const char *set_port_map(md_config_t *config, const char *value)
+{
+    int net_port, local_port;
+    char *endp;
+
+    net_port = (int)apr_strtoi64(value, &endp, 10);
+    if (errno) {
+        return "unable to parse first port number";
+    }
+    if (!endp || *endp != ':') {
+        return "no ':' after first port number";
+    }
+    ++endp;
+    if (*endp == '-') {
+        local_port = 0;
+    }
+    else {
+        local_port = (int)apr_strtoi64(endp, &endp, 10);
+        if (errno) {
+            return "unable to parse second port number";
+        }
+        if (local_port <= 0 || local_port > 65535) {
+            return "invalid number for port map, must be in ]0,65535]";
+        }
+    }
+    switch (net_port) {
+        case 80:
+            config->local_80 = local_port;
+            break;
+        case 443:
+            config->local_443 = local_port;
+            break;
+        default:
+            return "mapped port number must be 80 or 443";
+    }
+    return NULL;
+}
+
+static const char *md_config_set_port_map(cmd_parms *cmd, void *arg, 
+                                          const char *v1, const char *v2)
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
+
+    (void)arg;
+    if (!err) {
+        err = set_port_map(config, v1);
+    }
+    if (!err && v2) {
+        err = set_port_map(config, v2);
+    }
+    return err;
+}
+
+static const char *md_config_set_cha_tyes(cmd_parms *cmd, void *dc, 
+                                          int argc, char *const argv[])
+{
+    md_config_t *config = (md_config_t *)md_config_get(cmd->server);
+    apr_array_header_t **pcha, *ca_challenges;
+    const char *err;
+    int i;
+
+    if (inside_section(cmd)) {
+        md_config_dir_t *dconf = dc;
+        pcha = &dconf->md->ca_challenges;
+    }
+    else {
+        if (NULL != (err = ap_check_cmd_context(cmd, GLOBAL_ONLY))) {
+            return err;
+        }
+        pcha = &config->ca_challenges; 
+    }
+    
+    ca_challenges = *pcha;
+    if (!ca_challenges) {
+        *pcha = ca_challenges = apr_array_make(cmd->pool, 5, sizeof(const char *));
+    }
+    for (i = 0; i < argc; ++i) {
+        APR_ARRAY_PUSH(ca_challenges, const char *) = argv[i];
+    }
+    
+    return NULL;
+}
+
+
+#define AP_END_CMD     AP_INIT_TAKE1(NULL, NULL, NULL, RSRC_CONF, NULL)
+
+const command_rec md_cmds[] = {
+    AP_INIT_RAW_ARGS("<ManagedDomain", md_config_sec_start, NULL, RSRC_CONF, 
+                      "Container for a manged domain with common settings and certificate."),
+    AP_INIT_TAKE_ARGV("MDMember", md_config_sec_add_members, NULL, OR_ALL, 
+                      "Define domain name(s) part of the Managed Domain"),
+    AP_INIT_TAKE_ARGV("ManagedDomain", md_config_set_names, NULL, RSRC_CONF, 
+                      "A group of server names with one certificate"),
+    AP_INIT_TAKE1("MDCertificateAuthority", md_config_set_ca, NULL, RSRC_CONF, 
+                  "URL of CA issueing the certificates"),
+    AP_INIT_TAKE1("MDStoreDir", md_config_set_store_dir, NULL, RSRC_CONF, 
+                  "the directory for file system storage of managed domain data."),
+    AP_INIT_TAKE1("MDCertificateProtocol", md_config_set_ca_proto, NULL, RSRC_CONF, 
+                  "Protocol used to obtain/renew certificates"),
+    AP_INIT_TAKE1("MDCertificateAgreement", md_config_set_agreement, NULL, RSRC_CONF, 
+                  "URL of CA Terms-of-Service agreement you accept"),
+    AP_INIT_TAKE1("MDDriveMode", md_config_set_drive_mode, NULL, RSRC_CONF, 
+                  "method of obtaining certificates for the managed domain"),
+    AP_INIT_TAKE1("MDRenewWindow", md_config_set_renew_window, NULL, RSRC_CONF, 
+                  "Time length for renewal before certificate expires (defaults to days)"),
+    AP_INIT_TAKE12("MDPortMap", md_config_set_port_map, NULL, RSRC_CONF, 
+                  "Declare the mapped ports 80 and 443 on the local server. E.g. 80:8000 "
+                  "to indicate that the server port 8000 is reachable as port 80 from the "
+                  "internet. Use 80:- to indicate that port 80 is not reachable from "
+                  "the outside."),
+    AP_INIT_TAKE_ARGV("MDCAChallenges", md_config_set_cha_tyes, NULL, RSRC_CONF, 
+                      "A list of challenge types to be used."),
+    AP_END_CMD
+};
+
+
+static const md_config_t *config_get_int(server_rec *s, apr_pool_t *p)
+{
+    md_config_t *cfg = (md_config_t *)ap_get_module_config(s->module_config, &md_module);
+    ap_assert(cfg);
+    if (cfg->s != s && p) {
+        cfg = md_config_merge(p, &defconf, cfg);
+        cfg->name = apr_pstrcat(p, CONF_S_NAME(s), cfg->name, NULL);
+        ap_set_module_config(s->module_config, &md_module, cfg);
+    }
+    return cfg;
+}
+
+const md_config_t *md_config_get(server_rec *s)
+{
+    return config_get_int(s, NULL);
+}
+
+const md_config_t *md_config_get_unique(server_rec *s, apr_pool_t *p)
+{
+    assert(p);
+    return config_get_int(s, p);
+}
+
+const md_config_t *md_config_cget(conn_rec *c)
+{
+    return md_config_get(c->base_server);
+}
+
+const char *md_config_gets(const md_config_t *config, md_config_var_t var)
+{
+    switch (var) {
+        case MD_CONFIG_CA_URL:
+            return config->ca_url? config->ca_url : defconf.ca_url;
+        case MD_CONFIG_CA_PROTO:
+            return config->ca_proto? config->ca_proto : defconf.ca_proto;
+        case MD_CONFIG_BASE_DIR:
+            return config->base_dir? config->base_dir : defconf.base_dir;
+        case MD_CONFIG_CA_AGREEMENT:
+            return config->ca_agreement? config->ca_agreement : defconf.ca_agreement;
+        default:
+            return NULL;
+    }
+}
+
+int md_config_geti(const md_config_t *config, md_config_var_t var)
+{
+    switch (var) {
+        case MD_CONFIG_DRIVE_MODE:
+            return (config->drive_mode != DEF_VAL)? config->drive_mode : defconf.drive_mode;
+        case MD_CONFIG_LOCAL_80:
+            return (config->local_80 != DEF_VAL)? config->local_80 : 80;
+        case MD_CONFIG_LOCAL_443:
+            return (config->local_443 != DEF_VAL)? config->local_443 : 443;
+        default:
+            return 0;
+    }
+}
+
+apr_interval_time_t md_config_get_interval(const md_config_t *config, md_config_var_t var)
+{
+    switch (var) {
+        case MD_CONFIG_RENEW_WINDOW:
+            return (config->renew_window != DEF_VAL)? config->renew_window : defconf.renew_window;
+        default:
+            return 0;
+    }
+}
diff --git a/modules/md/md_config.h b/modules/md/md_config.h
new file mode 100644
index 0000000000..3568f7c6ac
--- /dev/null
+++ b/modules/md/md_config.h
@@ -0,0 +1,77 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_config_h
+#define mod_md_md_config_h
+
+struct md_store_t;
+
+typedef enum {
+    MD_CONFIG_CA_URL,
+    MD_CONFIG_CA_PROTO,
+    MD_CONFIG_BASE_DIR,
+    MD_CONFIG_CA_AGREEMENT,
+    MD_CONFIG_DRIVE_MODE,
+    MD_CONFIG_LOCAL_80,
+    MD_CONFIG_LOCAL_443,
+    MD_CONFIG_RENEW_WINDOW,
+} md_config_var_t;
+
+typedef struct {
+    const char *name;
+    const server_rec *s;
+    
+    int local_80;
+    int local_443;
+    
+    apr_array_header_t *mds;           /* array of md_t pointers */
+    const char *ca_url;
+    const char *ca_proto;
+    const char *ca_agreement;
+    apr_array_header_t *ca_challenges; /* challenge types allowed */
+    
+    int drive_mode;
+    apr_interval_time_t renew_window;  /* time for renewal before expiry */
+    
+    const md_t *md;
+    const char *base_dir;
+    struct md_store_t *store;
+
+} md_config_t;
+
+typedef struct {
+    md_t *md;
+} md_config_dir_t;
+
+void *md_config_create_svr(apr_pool_t *pool, server_rec *s);
+void *md_config_merge_svr(apr_pool_t *pool, void *basev, void *addv);
+void *md_config_create_dir(apr_pool_t *pool, char *dummy);
+void *md_config_merge_dir(apr_pool_t *pool, void *basev, void *addv);
+
+extern const command_rec md_cmds[];
+
+/* Get the effective md configuration for the connection */
+const md_config_t *md_config_cget(conn_rec *c);
+/* Get the effective md configuration for the server */
+const md_config_t *md_config_get(server_rec *s);
+/* Get the effective md configuration for the server, but make it
+ * unique to this server_rec, so that any changes only affect this server */
+const md_config_t *md_config_get_unique(server_rec *s, apr_pool_t *p);
+
+const char *md_config_gets(const md_config_t *config, md_config_var_t var);
+int md_config_geti(const md_config_t *config, md_config_var_t var);
+apr_interval_time_t md_config_get_interval(const md_config_t *config, md_config_var_t var);
+
+#endif /* md_config_h */
diff --git a/modules/md/md_core.c b/modules/md/md_core.c
new file mode 100644
index 0000000000..a65c639f07
--- /dev/null
+++ b/modules/md/md_core.c
@@ -0,0 +1,321 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_tables.h>
+#include <apr_time.h>
+#include <apr_date.h>
+
+#include "md_json.h"
+#include "md.h"
+#include "md_log.h"
+#include "md_store.h"
+#include "md_util.h"
+
+
+int md_contains(const md_t *md, const char *domain)
+{
+   return md_array_str_index(md->domains, domain, 0, 0) >= 0;
+}
+
+const char *md_common_name(const md_t *md1, const md_t *md2)
+{
+    int i;
+    
+    if (md1 == NULL || md1->domains == NULL
+        || md2 == NULL || md2->domains == NULL) {
+        return NULL;
+    }
+    
+    for (i = 0; i < md1->domains->nelts; ++i) {
+        const char *name1 = APR_ARRAY_IDX(md1->domains, i, const char*);
+        if (md_contains(md2, name1)) {
+            return name1;
+        }
+    }
+    return NULL;
+}
+
+int md_domains_overlap(const md_t *md1, const md_t *md2)
+{
+    return md_common_name(md1, md2) != NULL;
+}
+
+apr_size_t md_common_name_count(const md_t *md1, const md_t *md2)
+{
+    int i;
+    apr_size_t hits;
+    
+    if (md1 == NULL || md1->domains == NULL
+        || md2 == NULL || md2->domains == NULL) {
+        return 0;
+    }
+    
+    hits = 0;
+    for (i = 0; i < md1->domains->nelts; ++i) {
+        const char *name1 = APR_ARRAY_IDX(md1->domains, i, const char*);
+        if (md_contains(md2, name1)) {
+            ++hits;
+        }
+    }
+    return hits;
+}
+
+md_t *md_create_empty(apr_pool_t *p)
+{
+    md_t *md = apr_pcalloc(p, sizeof(*md));
+    if (md) {
+        md->domains = apr_array_make(p, 5, sizeof(const char *));
+        md->contacts = apr_array_make(p, 5, sizeof(const char *));
+        md->drive_mode = MD_DRIVE_DEFAULT;
+        md->defn_name = "unknown";
+        md->defn_line_number = 0;
+    }
+    return md;
+}
+
+int md_equal_domains(const md_t *md1, const md_t *md2)
+{
+    int i;
+    if (md1->domains->nelts == md2->domains->nelts) {
+        for (i = 0; i < md1->domains->nelts; ++i) {
+            const char *name1 = APR_ARRAY_IDX(md1->domains, i, const char*);
+            if (!md_contains(md2, name1)) {
+                return 0;
+            }
+        }
+        return 1;
+    }
+    return 0;
+}
+
+int md_contains_domains(const md_t *md1, const md_t *md2)
+{
+    int i;
+    if (md1->domains->nelts >= md2->domains->nelts) {
+        for (i = 0; i < md2->domains->nelts; ++i) {
+            const char *name2 = APR_ARRAY_IDX(md2->domains, i, const char*);
+            if (!md_contains(md1, name2)) {
+                return 0;
+            }
+        }
+        return 1;
+    }
+    return 0;
+}
+
+md_t *md_find_closest_match(apr_array_header_t *mds, const md_t *md)
+{
+    md_t *candidate, *m;
+    apr_size_t cand_n, n;
+    int i;
+    
+    candidate = md_get_by_name(mds, md->name);
+    if (!candidate) {
+        /* try to find an instance that contains all domain names from md */ 
+        for (i = 0; i < mds->nelts; ++i) {
+            m = APR_ARRAY_IDX(mds, i, md_t *);
+            if (md_contains_domains(m, md)) {
+                return m;
+            }
+        }
+        /* no matching name and no md in the list has all domains.
+         * We consider that managed domain as closest match that contains at least one
+         * domain name from md, ONLY if there is no other one that also has.
+         */
+        cand_n = 0;
+        for (i = 0; i < mds->nelts; ++i) {
+            m = APR_ARRAY_IDX(mds, i, md_t *);
+            n = md_common_name_count(md, m);
+            if (n > cand_n) {
+                candidate = m;
+                cand_n = n;
+            }
+        }
+    }
+    return candidate;
+}
+
+md_t *md_get_by_name(struct apr_array_header_t *mds, const char *name)
+{
+    int i;
+    for (i = 0; i < mds->nelts; ++i) {
+        md_t *md = APR_ARRAY_IDX(mds, i, md_t *);
+        if (!strcmp(name, md->name)) {
+            return md;
+        }
+    }
+    return NULL;
+}
+
+md_t *md_get_by_domain(struct apr_array_header_t *mds, const char *domain)
+{
+    int i;
+    for (i = 0; i < mds->nelts; ++i) {
+        md_t *md = APR_ARRAY_IDX(mds, i, md_t *);
+        if (md_contains(md, domain)) {
+            return md;
+        }
+    }
+    return NULL;
+}
+
+md_t *md_get_by_dns_overlap(struct apr_array_header_t *mds, const md_t *md)
+{
+    int i;
+    for (i = 0; i < mds->nelts; ++i) {
+        md_t *o = APR_ARRAY_IDX(mds, i, md_t *);
+        if (strcmp(o->name, md->name) && md_common_name(o, md)) {
+            return o;
+        }
+    }
+    return NULL;
+}
+
+const char *md_create(md_t **pmd, apr_pool_t *p, apr_array_header_t *domains)
+{
+    md_t *md;
+    
+    if (domains->nelts <= 0) {
+        return "needs at least one domain name";
+    }
+    
+    md = md_create_empty(p);
+    if (!md) {
+        return "not enough memory";
+    }
+
+    md->domains = md_array_str_compact(p, domains, 0);
+    md->name = APR_ARRAY_IDX(md->domains, 0, const char *);
+    
+    *pmd = md;
+    return NULL;   
+}
+
+/**************************************************************************************************/
+/* lifetime */
+
+md_t *md_copy(apr_pool_t *p, const md_t *src)
+{
+    md_t *md;
+    
+    md = apr_pcalloc(p, sizeof(*md));
+    if (md) {
+        memcpy(md, src, sizeof(*md));
+        md->domains = apr_array_copy(p, src->domains);
+        md->contacts = apr_array_copy(p, src->contacts);
+        if (src->ca_challenges) {
+            md->ca_challenges = apr_array_copy(p, src->ca_challenges);
+        }
+    }    
+    return md;   
+}
+
+md_t *md_clone(apr_pool_t *p, const md_t *src)
+{
+    md_t *md;
+    
+    md = apr_pcalloc(p, sizeof(*md));
+    if (md) {
+        md->state = src->state;
+        md->name = apr_pstrdup(p, src->name);
+        md->drive_mode = src->drive_mode;
+        md->domains = md_array_str_compact(p, src->domains, 0);
+        md->renew_window = src->renew_window;
+        md->contacts = md_array_str_clone(p, src->contacts);
+        if (src->ca_url) md->ca_url = apr_pstrdup(p, src->ca_url);
+        if (src->ca_proto) md->ca_proto = apr_pstrdup(p, src->ca_proto);
+        if (src->ca_account) md->ca_account = apr_pstrdup(p, src->ca_account);
+        if (src->ca_agreement) md->ca_agreement = apr_pstrdup(p, src->ca_agreement);
+        if (src->defn_name) md->defn_name = apr_pstrdup(p, src->defn_name);
+        if (src->cert_url) md->cert_url = apr_pstrdup(p, src->cert_url);
+        md->defn_line_number = src->defn_line_number;
+        if (src->ca_challenges) {
+            md->ca_challenges = md_array_str_clone(p, src->ca_challenges);
+        }
+    }    
+    return md;   
+}
+
+/**************************************************************************************************/
+/* format conversion */
+
+md_json_t *md_to_json(const md_t *md, apr_pool_t *p)
+{
+    md_json_t *json = md_json_create(p);
+    if (json) {
+        apr_array_header_t *domains = md_array_str_compact(p, md->domains, 0);
+        md_json_sets(md->name, json, MD_KEY_NAME, NULL);
+        md_json_setsa(domains, json, MD_KEY_DOMAINS, NULL);
+        md_json_setsa(md->contacts, json, MD_KEY_CONTACTS, NULL);
+        md_json_sets(md->ca_account, json, MD_KEY_CA, MD_KEY_ACCOUNT, NULL);
+        md_json_sets(md->ca_proto, json, MD_KEY_CA, MD_KEY_PROTO, NULL);
+        md_json_sets(md->ca_url, json, MD_KEY_CA, MD_KEY_URL, NULL);
+        md_json_sets(md->ca_agreement, json, MD_KEY_CA, MD_KEY_AGREEMENT, NULL);
+        if (md->cert_url) {
+            md_json_sets(md->cert_url, json, MD_KEY_CERT, MD_KEY_URL, NULL);
+        }
+        md_json_setl(md->state, json, MD_KEY_STATE, NULL);
+        md_json_setl(md->drive_mode, json, MD_KEY_DRIVE_MODE, NULL);
+        if (md->expires > 0) {
+            char *ts = apr_pcalloc(p, APR_RFC822_DATE_LEN);
+            apr_rfc822_date(ts, md->expires);
+            md_json_sets(ts, json, MD_KEY_CERT, MD_KEY_EXPIRES, NULL);
+        }
+        md_json_setl(apr_time_sec(md->renew_window), json, MD_KEY_RENEW_WINDOW, NULL);
+        if (md->ca_challenges && md->ca_challenges->nelts > 0) {
+            apr_array_header_t *na;
+            na = md_array_str_compact(p, md->ca_challenges, 0);
+            md_json_setsa(na, json, MD_KEY_CA, MD_KEY_CHALLENGES, NULL);
+        }
+        return json;
+    }
+    return NULL;
+}
+
+md_t *md_from_json(md_json_t *json, apr_pool_t *p)
+{
+    const char *s;
+    md_t *md = md_create_empty(p);
+    if (md) {
+        md->name = md_json_dups(p, json, MD_KEY_NAME, NULL);            
+        md_json_dupsa(md->domains, p, json, MD_KEY_DOMAINS, NULL);
+        md_json_dupsa(md->contacts, p, json, MD_KEY_CONTACTS, NULL);
+        md->ca_account = md_json_dups(p, json, MD_KEY_CA, MD_KEY_ACCOUNT, NULL);
+        md->ca_proto = md_json_dups(p, json, MD_KEY_CA, MD_KEY_PROTO, NULL);
+        md->ca_url = md_json_dups(p, json, MD_KEY_CA, MD_KEY_URL, NULL);
+        md->ca_agreement = md_json_dups(p, json, MD_KEY_CA, MD_KEY_AGREEMENT, NULL);
+        md->cert_url = md_json_dups(p, json, MD_KEY_CERT, MD_KEY_URL, NULL);
+        md->state = (int)md_json_getl(json, MD_KEY_STATE, NULL);
+        md->drive_mode = (int)md_json_getl(json, MD_KEY_DRIVE_MODE, NULL);
+        md->domains = md_array_str_compact(p, md->domains, 0);
+        s = md_json_dups(p, json, MD_KEY_CERT, MD_KEY_EXPIRES, NULL);
+        if (s && *s) {
+            md->expires = apr_date_parse_rfc(s);
+        }
+        md->renew_window = apr_time_from_sec(md_json_getl(json, MD_KEY_RENEW_WINDOW, NULL));
+        if (md_json_has_key(json, MD_KEY_CA, MD_KEY_CHALLENGES, NULL)) {
+            md->ca_challenges = apr_array_make(p, 5, sizeof(const char*));
+            md_json_dupsa(md->ca_challenges, p, json, MD_KEY_CA, MD_KEY_CHALLENGES, NULL);
+        }
+        return md;
+    }
+    return NULL;
+}
+
diff --git a/modules/md/md_crypt.c b/modules/md/md_crypt.c
new file mode 100644
index 0000000000..92b1f0c803
--- /dev/null
+++ b/modules/md/md_crypt.c
@@ -0,0 +1,1128 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_buckets.h>
+#include <apr_file_io.h>
+#include <apr_strings.h>
+
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+#include <openssl/rand.h>
+#include <openssl/rsa.h>
+#include <openssl/x509v3.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_log.h"
+#include "md_http.h"
+#include "md_util.h"
+
+/* getpid for *NIX */
+#if APR_HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#if APR_HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+/* getpid for Windows */
+#if APR_HAVE_PROCESS_H
+#include <process.h>
+#endif
+
+static int initialized;
+
+struct md_pkey_t {
+    apr_pool_t *pool;
+    EVP_PKEY   *pkey;
+};
+
+#ifdef MD_HAVE_ARC4RANDOM
+
+static void seed_RAND(int pid)
+{
+    char seed[128];
+    arc4random_buf(seed, sizeof(seed));
+    RAND_seed(seed, sizeof(seed));
+}
+
+#else /* ifdef MD_HAVE_ARC4RANDOM */
+
+static int rand_choosenum(int l, int h)
+{
+    int i;
+    char buf[50];
+
+    apr_snprintf(buf, sizeof(buf), "%.0f",
+                 (((double)(rand()%RAND_MAX)/RAND_MAX)*(h-l)));
+    i = atoi(buf)+1;
+    if (i < l) i = l;
+    if (i > h) i = h;
+    return i;
+}
+
+static void seed_RAND(int pid)
+{   
+    unsigned char stackdata[256];
+    /* stolen from mod_ssl/ssl_engine_rand.c */
+    apr_size_t n, l;
+    struct {
+        time_t t;
+        pid_t pid;
+    } my_seed;
+    
+    /*
+     * seed in the current time (usually just 4 bytes)
+     */
+    my_seed.t = time(NULL);
+    
+    /*
+     * seed in the current process id (usually just 4 bytes)
+     */
+    my_seed.pid = pid;
+    
+    l = sizeof(my_seed);
+    RAND_seed((unsigned char *)&my_seed, l);
+    
+    /*
+     * seed in some current state of the run-time stack (128 bytes)
+     */
+#if HAVE_VALGRIND && 0
+    if (ssl_running_on_valgrind) {
+        VALGRIND_MAKE_MEM_DEFINED(stackdata, sizeof(stackdata));
+    }
+#endif
+    n = rand_choosenum(0, sizeof(stackdata)-128-1);
+    RAND_seed(stackdata+n, 128);
+}
+
+#endif /*ifdef MD_HAVE_ARC4RANDOM (else part) */
+
+
+apr_status_t md_crypt_init(apr_pool_t *pool)
+{
+    (void)pool;
+    
+    if (!initialized) {
+        int pid = getpid();
+        
+        ERR_load_crypto_strings();
+        OpenSSL_add_all_algorithms();
+        
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE2, 0, pool, "initializing RAND"); 
+        while (!RAND_status()) {
+            seed_RAND(pid);
+	}
+
+        initialized = 1;
+    }
+    return APR_SUCCESS;
+}
+
+typedef struct {
+    char *data;
+    apr_size_t len;
+} buffer;
+
+static apr_status_t fwrite_buffer(void *baton, apr_file_t *f, apr_pool_t *p) 
+{
+    buffer *buf = baton;
+    return apr_file_write_full(f, buf->data, buf->len, &buf->len);
+}
+
+apr_status_t md_rand_bytes(unsigned char *buf, apr_size_t len, apr_pool_t *p)
+{
+    apr_status_t rv;
+    
+    if (len > INT_MAX) {
+        return APR_ENOTIMPL;
+    }
+    if (APR_SUCCESS == (rv = md_crypt_init(p))) {
+        RAND_bytes((unsigned char*)buf, (int)len);
+    }
+    return rv;
+}
+
+typedef struct {
+    const char *pass_phrase;
+    int pass_len;
+} passwd_ctx;
+
+static int pem_passwd(char *buf, int size, int rwflag, void *baton)
+{
+    passwd_ctx *ctx = baton;
+    if (ctx->pass_len > 0) {
+        if (ctx->pass_len < size) {
+            size = (int)ctx->pass_len;
+        }
+        memcpy(buf, ctx->pass_phrase, size);
+    }
+    return ctx->pass_len;
+}
+
+/**************************************************************************************************/
+/* private keys */
+
+static md_pkey_t *make_pkey(apr_pool_t *p) 
+{
+    md_pkey_t *pkey = apr_pcalloc(p, sizeof(*pkey));
+    pkey->pool = p;
+    return pkey;
+}
+
+static apr_status_t pkey_cleanup(void *data)
+{
+    md_pkey_t *pkey = data;
+    if (pkey->pkey) {
+        EVP_PKEY_free(pkey->pkey);
+        pkey->pkey = NULL;
+    }
+    return APR_SUCCESS;
+}
+
+void md_pkey_free(md_pkey_t *pkey)
+{
+    pkey_cleanup(pkey);
+}
+
+void *md_pkey_get_EVP_PKEY(struct md_pkey_t *pkey)
+{
+    return pkey->pkey;
+}
+
+apr_status_t md_pkey_fload(md_pkey_t **ppkey, apr_pool_t *p, 
+                           const char *key, apr_size_t key_len,
+                           const char *fname)
+{
+    apr_status_t rv = APR_ENOENT;
+    md_pkey_t *pkey;
+    BIO *bf;
+    passwd_ctx ctx;
+    
+    pkey =  make_pkey(p);
+    if (NULL != (bf = BIO_new_file(fname, "r"))) {
+        ctx.pass_phrase = key;
+        ctx.pass_len = (int)key_len;
+        
+        ERR_clear_error();
+        pkey->pkey = PEM_read_bio_PrivateKey(bf, NULL, pem_passwd, &ctx);
+        BIO_free(bf);
+        
+        if (pkey->pkey != NULL) {
+            rv = APR_SUCCESS;
+            apr_pool_cleanup_register(p, pkey, pkey_cleanup, apr_pool_cleanup_null);
+        }
+        else {
+            long err = ERR_get_error();
+            rv = APR_EINVAL;
+            md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, 
+                          "error loading pkey %s: %s (pass phrase was %snull)", fname,
+                          ERR_error_string(err, NULL), key? "not " : ""); 
+        }
+    }
+    *ppkey = (APR_SUCCESS == rv)? pkey : NULL;
+    return rv;
+}
+
+static apr_status_t pkey_to_buffer(buffer *buffer, md_pkey_t *pkey, apr_pool_t *p,
+                                   const char *pass, apr_size_t pass_len)
+{
+    BIO *bio = BIO_new(BIO_s_mem());
+    const EVP_CIPHER *cipher = NULL;
+    pem_password_cb *cb = NULL;
+    void *cb_baton = NULL;
+    passwd_ctx ctx;
+    unsigned long err;
+    
+    if (!bio) {
+        return APR_ENOMEM;
+    }
+    if (pass_len > INT_MAX) {
+        return APR_EINVAL;
+    }
+    if (pass && pass_len > 0) {
+        ctx.pass_phrase = pass;
+        ctx.pass_len = (int)pass_len;
+        cb = pem_passwd;
+        cb_baton = &ctx;
+        cipher = EVP_aes_256_cbc();
+        if (!cipher) {
+            return APR_ENOTIMPL;
+        }
+    }
+    
+    ERR_clear_error();
+    if (!PEM_write_bio_PrivateKey(bio, pkey->pkey, cipher, NULL, 0, cb, cb_baton)) {
+        BIO_free(bio);
+        err = ERR_get_error();
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "PEM_write key: %ld %s", 
+                      err, ERR_error_string(err, NULL)); 
+        return APR_EINVAL;
+    }
+
+    buffer->len = BIO_pending(bio);
+    if (buffer->len > 0) {
+        buffer->data = apr_palloc(p, buffer->len+1);
+        buffer->len = BIO_read(bio, buffer->data, (int)buffer->len);
+        buffer->data[buffer->len] = '\0';
+    }
+    BIO_free(bio);
+    return APR_SUCCESS;
+}
+
+apr_status_t md_pkey_fsave(md_pkey_t *pkey, apr_pool_t *p, 
+                           const char *pass_phrase, apr_size_t pass_len,
+                           const char *fname, apr_fileperms_t perms)
+{
+    buffer buffer;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = pkey_to_buffer(&buffer, pkey, p, pass_phrase, pass_len))) {
+        return md_util_freplace(fname, perms, p, fwrite_buffer, &buffer); 
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "save pkey %s (%s pass phrase, len=%d)",
+                  fname, pass_len > 0? "with" : "without", (int)pass_len); 
+    return rv;
+}
+
+apr_status_t md_pkey_gen_rsa(md_pkey_t **ppkey, apr_pool_t *p, int bits)
+{
+    EVP_PKEY_CTX *ctx = NULL;
+    apr_status_t rv;
+    
+    *ppkey = make_pkey(p);
+    ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
+    if (ctx 
+        && EVP_PKEY_keygen_init(ctx) >= 0
+        && EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, bits) >= 0
+        && EVP_PKEY_keygen(ctx, &(*ppkey)->pkey) >= 0) {
+        rv = APR_SUCCESS;
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, p, "unable to generate new key"); 
+        *ppkey = NULL;
+        rv = APR_EGENERAL;
+    }
+    
+    if (ctx != NULL) {
+        EVP_PKEY_CTX_free(ctx);
+    }
+    return rv;
+}
+
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
+#ifndef NID_tlsfeature
+#define NID_tlsfeature          1020
+#endif
+
+static void RSA_get0_key(const RSA *r,
+                         const BIGNUM **n, const BIGNUM **e, const BIGNUM **d)
+{
+    if (n != NULL)
+        *n = r->n;
+    if (e != NULL)
+        *e = r->e;
+    if (d != NULL)
+        *d = r->d;
+}
+
+#endif
+
+static const char *bn64(const BIGNUM *b, apr_pool_t *p) 
+{
+    if (b) {
+         int len = BN_num_bytes(b);
+         char *buffer = apr_pcalloc(p, len);
+         if (buffer) {
+            BN_bn2bin(b, (unsigned char *)buffer);
+            return md_util_base64url_encode(buffer, len, p);
+         }
+    }
+    return NULL;
+}
+
+const char *md_pkey_get_rsa_e64(md_pkey_t *pkey, apr_pool_t *p)
+{
+    const BIGNUM *e;
+    RSA *rsa = EVP_PKEY_get1_RSA(pkey->pkey);
+    
+    if (!rsa) {
+        return NULL;
+    }
+    RSA_get0_key(rsa, NULL, &e, NULL);
+    return bn64(e, p);
+}
+
+const char *md_pkey_get_rsa_n64(md_pkey_t *pkey, apr_pool_t *p)
+{
+    const BIGNUM *n;
+    RSA *rsa = EVP_PKEY_get1_RSA(pkey->pkey);
+    
+    if (!rsa) {
+        return NULL;
+    }
+    RSA_get0_key(rsa, &n, NULL, NULL);
+    return bn64(n, p);
+}
+
+apr_status_t md_crypt_sign64(const char **psign64, md_pkey_t *pkey, apr_pool_t *p, 
+                             const char *d, size_t dlen)
+{
+    EVP_MD_CTX *ctx = NULL;
+    char *buffer;
+    unsigned int blen;
+    const char *sign64 = NULL;
+    apr_status_t rv = APR_ENOMEM;
+    
+    buffer = apr_pcalloc(p, EVP_PKEY_size(pkey->pkey));
+    if (buffer) {
+        ctx = EVP_MD_CTX_create();
+        if (ctx) {
+            rv = APR_ENOTIMPL;
+            if (EVP_SignInit_ex(ctx, EVP_sha256(), NULL)) {
+                rv = APR_EGENERAL;
+                if (EVP_SignUpdate(ctx, d, dlen)) {
+                    if (EVP_SignFinal(ctx, (unsigned char*)buffer, &blen, pkey->pkey)) {
+                        sign64 = md_util_base64url_encode(buffer, blen, p);
+                        if (sign64) {
+                            rv = APR_SUCCESS;
+                        }
+                    }
+                }
+            }
+        }
+        
+        if (ctx) {
+            EVP_MD_CTX_destroy(ctx);
+        }
+    }
+    
+    if (rv != APR_SUCCESS) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, "signing"); 
+    }
+    
+    *psign64 = sign64;
+    return rv;
+}
+
+static apr_status_t sha256_digest(unsigned char **pdigest, size_t *pdigest_len,
+                                  apr_pool_t *p, const char *d, size_t dlen)
+{
+    EVP_MD_CTX *ctx = NULL;
+    unsigned char *buffer;
+    apr_status_t rv = APR_ENOMEM;
+    unsigned int blen;
+    
+    buffer = apr_pcalloc(p, EVP_MAX_MD_SIZE);
+    if (buffer) {
+        ctx = EVP_MD_CTX_create();
+        if (ctx) {
+            rv = APR_ENOTIMPL;
+            if (EVP_DigestInit_ex(ctx, EVP_sha256(), NULL)) {
+                rv = APR_EGENERAL;
+                if (EVP_DigestUpdate(ctx, d, dlen)) {
+                    if (EVP_DigestFinal(ctx, buffer, &blen)) {
+                        rv = APR_SUCCESS;
+                    }
+                }
+            }
+        }
+        
+        if (ctx) {
+            EVP_MD_CTX_destroy(ctx);
+        }
+    }
+    
+    if (APR_SUCCESS == rv) {
+        *pdigest = buffer;
+        *pdigest_len = blen;
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, "digest"); 
+        *pdigest = NULL;
+        *pdigest_len = 0;
+    }
+    return rv;
+}
+
+apr_status_t md_crypt_sha256_digest64(const char **pdigest64, apr_pool_t *p, 
+                                      const char *d, size_t dlen)
+{
+    const char *digest64 = NULL;
+    unsigned char *buffer;
+    size_t blen;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = sha256_digest(&buffer, &blen, p, d, dlen))) {
+        if (NULL == (digest64 = md_util_base64url_encode((const char*)buffer, blen, p))) {
+            rv = APR_EGENERAL;
+        }
+    }
+    *pdigest64 = digest64;
+    return rv;
+}
+
+static const char * const hex_const[] = {
+    "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "0a", "0b", "0c", "0d", "0e", "0f", 
+    "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "1a", "1b", "1c", "1d", "1e", "1f", 
+    "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "2a", "2b", "2c", "2d", "2e", "2f", 
+    "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "3a", "3b", "3c", "3d", "3e", "3f", 
+    "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "4a", "4b", "4c", "4d", "4e", "4f", 
+    "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "5a", "5b", "5c", "5d", "5e", "5f", 
+    "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "6a", "6b", "6c", "6d", "6e", "6f", 
+    "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "7a", "7b", "7c", "7d", "7e", "7f", 
+    "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "8a", "8b", "8c", "8d", "8e", "8f", 
+    "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "9a", "9b", "9c", "9d", "9e", "9f", 
+    "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "aa", "ab", "ac", "ad", "ae", "af", 
+    "b0", "b1", "b2", "b3", "b4", "b5", "b6", "b7", "b8", "b9", "ba", "bb", "bc", "bd", "be", "bf", 
+    "c0", "c1", "c2", "c3", "c4", "c5", "c6", "c7", "c8", "c9", "ca", "cb", "cc", "cd", "ce", "cf", 
+    "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7", "d8", "d9", "da", "db", "dc", "dd", "de", "df", 
+    "e0", "e1", "e2", "e3", "e4", "e5", "e6", "e7", "e8", "e9", "ea", "eb", "ec", "ed", "ee", "ef", 
+    "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9", "fa", "fb", "fc", "fd", "fe", "ff", 
+};
+
+apr_status_t md_crypt_sha256_digest_hex(const char **pdigesthex, apr_pool_t *p, 
+                                        const char *d, size_t dlen)
+{
+    char *dhex = NULL, *cp;
+    const char * x;
+    unsigned char *buffer;
+    size_t blen;
+    apr_status_t rv;
+    int i;
+    
+    if (APR_SUCCESS == (rv = sha256_digest(&buffer, &blen, p, d, dlen))) {
+        cp = dhex = apr_pcalloc(p,  2 * blen + 1);
+        if (!dhex) {
+            rv = APR_EGENERAL;
+        }
+        for (i = 0; i < blen; ++i, cp += 2) {
+            x = hex_const[buffer[i]];
+            cp[0] = x[0];
+            cp[1] = x[1];
+        }
+    }
+    *pdigesthex = dhex;
+    return rv;
+}
+
+/**************************************************************************************************/
+/* certificates */
+
+struct md_cert_t {
+    apr_pool_t *pool;
+    X509 *x509;
+    apr_array_header_t *alt_names;
+};
+
+static apr_status_t cert_cleanup(void *data)
+{
+    md_cert_t *cert = data;
+    if (cert->x509) {
+        X509_free(cert->x509);
+        cert->x509 = NULL;
+    }
+    return APR_SUCCESS;
+}
+
+static md_cert_t *make_cert(apr_pool_t *p, X509 *x509) 
+{
+    md_cert_t *cert = apr_pcalloc(p, sizeof(*cert));
+    cert->pool = p;
+    cert->x509 = x509;
+    apr_pool_cleanup_register(p, cert, cert_cleanup, apr_pool_cleanup_null);
+    
+    return cert;
+}
+
+void md_cert_free(md_cert_t *cert)
+{
+    cert_cleanup(cert);
+}
+
+void *md_cert_get_X509(struct md_cert_t *cert)
+{
+    return cert->x509;
+}
+
+int md_cert_is_valid_now(const md_cert_t *cert)
+{
+    return ((X509_cmp_current_time(X509_get_notBefore(cert->x509)) < 0)
+            && (X509_cmp_current_time(X509_get_notAfter(cert->x509)) > 0));
+}
+
+int md_cert_has_expired(const md_cert_t *cert)
+{
+    return (X509_cmp_current_time(X509_get_notAfter(cert->x509)) <= 0);
+}
+
+apr_time_t md_cert_get_not_after(md_cert_t *cert)
+{
+    int secs, days;
+    apr_time_t time = apr_time_now();
+    ASN1_TIME *not_after = X509_get_notAfter(cert->x509);
+    
+    if (ASN1_TIME_diff(&days, &secs, NULL, not_after)) {
+        time += apr_time_from_sec((days * MD_SECS_PER_DAY) + secs); 
+    }
+    return time;
+}
+
+int md_cert_covers_domain(md_cert_t *cert, const char *domain_name)
+{
+    if (!cert->alt_names) {
+        md_cert_get_alt_names(&cert->alt_names, cert, cert->pool);
+    }
+    if (cert->alt_names) {
+        return md_array_str_index(cert->alt_names, domain_name, 0, 0) >= 0;
+    }
+    return 0;
+}
+
+int md_cert_covers_md(md_cert_t *cert, const md_t *md)
+{
+    const char *name;
+    int i;
+    
+    if (!cert->alt_names) {
+        md_cert_get_alt_names(&cert->alt_names, cert, cert->pool);
+    }
+    if (cert->alt_names) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE4, 0, cert->pool, "cert has %d alt names",
+                      cert->alt_names->nelts); 
+        for (i = 0; i < md->domains->nelts; ++i) {
+            name = APR_ARRAY_IDX(md->domains, i, const char *);
+            if (md_array_str_index(cert->alt_names, name, 0, 0) < 0) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, cert->pool, 
+                              "md domain %s not covered by cert", name);
+                return 0;
+            }
+        }
+        return 1;
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, cert->pool, "cert has NO alt names");
+    }
+    return 0;
+}
+
+apr_status_t md_cert_get_issuers_uri(const char **puri, md_cert_t *cert, apr_pool_t *p)
+{
+    int i, ext_idx, nid = NID_info_access;
+    X509_EXTENSION *ext;
+    X509V3_EXT_METHOD *ext_cls;
+    void *ext_data;
+    const char *uri = NULL;
+    apr_status_t rv = APR_ENOENT;
+    
+    /* Waddle through x509  API history to get someone that may be able
+     * to hand us the issuer url for the cert chain */
+    ext_idx = X509_get_ext_by_NID(cert->x509, nid, -1);
+    ext = (ext_idx >= 0)? X509_get_ext(cert->x509, ext_idx) : NULL;
+    ext_cls = ext? (X509V3_EXT_METHOD*)X509V3_EXT_get(ext) : NULL;
+    if (ext_cls && (ext_data = X509_get_ext_d2i(cert->x509, nid, 0, 0))) {
+        CONF_VALUE *cval;
+        STACK_OF(CONF_VALUE) *ext_vals = ext_cls->i2v(ext_cls, ext_data, 0);
+        
+        for (i = 0; i < sk_CONF_VALUE_num(ext_vals); ++i) {
+            cval = sk_CONF_VALUE_value(ext_vals, i);
+            if (!strcmp("CA Issuers - URI", cval->name)) {
+                uri = apr_pstrdup(p, cval->value);
+                rv = APR_SUCCESS;
+                break;
+            }
+        }
+    } 
+    *puri = (APR_SUCCESS == rv)? uri : NULL;
+    return rv;
+}
+
+apr_status_t md_cert_get_alt_names(apr_array_header_t **pnames, md_cert_t *cert, apr_pool_t *p)
+{
+    apr_array_header_t *names;
+    apr_status_t rv = APR_ENOENT;
+    STACK_OF(GENERAL_NAME) *xalt_names;
+    unsigned char *buf;
+    int i;
+    
+    xalt_names = (GENERAL_NAMES*)X509_get_ext_d2i(cert->x509, NID_subject_alt_name, NULL, NULL);
+    if (xalt_names) {
+        GENERAL_NAME *cval;
+        
+        names = apr_array_make(p, sk_GENERAL_NAME_num(xalt_names), sizeof(char *));
+        for (i = 0; i < sk_GENERAL_NAME_num(xalt_names); ++i) {
+            cval = sk_GENERAL_NAME_value(xalt_names, i);
+            switch (cval->type) {
+                case GEN_DNS:
+                case GEN_URI:
+                case GEN_IPADD:
+                    ASN1_STRING_to_UTF8(&buf, cval->d.ia5);
+                    APR_ARRAY_PUSH(names, const char *) = apr_pstrdup(p, (char*)buf);
+                    OPENSSL_free(buf);
+                    break;
+                default:
+                    break;
+            }
+        }
+        rv = APR_SUCCESS;
+    }
+    *pnames = (APR_SUCCESS == rv)? names : NULL;
+    return rv;
+}
+
+apr_status_t md_cert_fload(md_cert_t **pcert, apr_pool_t *p, const char *fname)
+{
+    FILE *f;
+    apr_status_t rv;
+    md_cert_t *cert;
+    X509 *x509;
+    
+    rv = md_util_fopen(&f, fname, "r");
+    if (rv == APR_SUCCESS) {
+    
+        x509 = PEM_read_X509(f, NULL, NULL, NULL);
+        rv = fclose(f);
+        if (x509 != NULL) {
+            cert =  make_cert(p, x509);
+        }
+        else {
+            rv = APR_EINVAL;
+        }
+    }
+
+    *pcert = (APR_SUCCESS == rv)? cert : NULL;
+    return rv;
+}
+
+static apr_status_t cert_to_buffer(buffer *buffer, md_cert_t *cert, apr_pool_t *p)
+{
+    BIO *bio = BIO_new(BIO_s_mem());
+    
+    if (!bio) {
+        return APR_ENOMEM;
+    }
+
+    ERR_clear_error();
+    PEM_write_bio_X509(bio, cert->x509);
+    if (ERR_get_error() > 0) {
+        BIO_free(bio);
+        return APR_EINVAL;
+    }
+
+    buffer->len = BIO_pending(bio);
+    if (buffer->len > 0) {
+        buffer->data = apr_palloc(p, buffer->len+1);
+        buffer->len = BIO_read(bio, buffer->data, (int)buffer->len);
+        buffer->data[buffer->len] = '\0';
+    }
+    BIO_free(bio);
+    return APR_SUCCESS;
+}
+
+apr_status_t md_cert_fsave(md_cert_t *cert, apr_pool_t *p, 
+                           const char *fname, apr_fileperms_t perms)
+{
+    buffer buffer;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = cert_to_buffer(&buffer, cert, p))) {
+        return md_util_freplace(fname, perms, p, fwrite_buffer, &buffer); 
+    }
+    return rv;
+}
+
+apr_status_t md_cert_to_base64url(const char **ps64, md_cert_t *cert, apr_pool_t *p)
+{
+    buffer buffer;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = cert_to_buffer(&buffer, cert, p))) {
+        *ps64 = md_util_base64url_encode(buffer.data, buffer.len, p);
+        return APR_SUCCESS;
+    }
+    *ps64 = NULL;
+    return rv;
+}
+
+apr_status_t md_cert_read_http(md_cert_t **pcert, apr_pool_t *p, 
+                               const md_http_response_t *res)
+{
+    const char *ct;
+    apr_off_t data_len;
+    apr_size_t der_len;
+    apr_status_t rv;
+    
+    ct = apr_table_get(res->headers, "Content-Type");
+    if (!res->body || !ct  || strcmp("application/pkix-cert", ct)) {
+        return APR_ENOENT;
+    }
+    
+    if (APR_SUCCESS == (rv = apr_brigade_length(res->body, 1, &data_len))) {
+        char *der;
+        if (data_len > 1024*1024) { /* certs usually are <2k each */
+            return APR_EINVAL;
+        }
+        if (APR_SUCCESS == (rv = apr_brigade_pflatten(res->body, &der, &der_len, p))) {
+            const unsigned char *bf = (const unsigned char*)der;
+            X509 *x509;
+            
+            if (NULL == (x509 = d2i_X509(NULL, &bf, der_len))) {
+                rv = APR_EINVAL;
+            }
+            else {
+                *pcert = make_cert(p, x509);
+                rv = APR_SUCCESS;
+            }
+        }
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, rv, p, "cert parsed");
+    }
+    return rv;
+}
+
+md_cert_state_t md_cert_state_get(md_cert_t *cert)
+{
+    if (cert->x509) {
+        return md_cert_is_valid_now(cert)? MD_CERT_VALID : MD_CERT_EXPIRED;
+    }
+    return MD_CERT_UNKNOWN;
+}
+
+apr_status_t md_chain_fload(apr_array_header_t **pcerts, apr_pool_t *p, const char *fname)
+{
+    FILE *f;
+    apr_status_t rv;
+    apr_array_header_t *certs = NULL;
+    X509 *x509;
+    md_cert_t *cert;
+    unsigned long err;
+    
+    rv = md_util_fopen(&f, fname, "r");
+    if (rv == APR_SUCCESS) {
+        certs = apr_array_make(p, 5, sizeof(md_cert_t *));
+        
+        ERR_clear_error();
+        while (NULL != (x509 = PEM_read_X509(f, NULL, NULL, NULL))) {
+            cert = make_cert(p, x509);
+            APR_ARRAY_PUSH(certs, md_cert_t *) = cert;
+        }
+        fclose(f);
+        
+        if (0 < (err =  ERR_get_error())
+            && !(ERR_GET_LIB(err) == ERR_LIB_PEM && ERR_GET_REASON(err) == PEM_R_NO_START_LINE)) {
+            /* not the expected one when no more PEM encodings are found */
+            rv = APR_EINVAL;
+            goto out;
+        }
+        
+        if (certs->nelts == 0) {
+            /* Did not find any. This is acceptable unless the file has a certain size
+             * when we no longer accept it as empty chain file. Something seems to be
+             * wrong then. */
+            apr_finfo_t info;
+            if (APR_SUCCESS == apr_stat(&info, fname, APR_FINFO_SIZE, p) && info.size >= 1024) {
+                /* "Too big for a moon." */
+                rv = APR_EINVAL;
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, 
+                              "no certificates in non-empty chain %s", fname);
+                goto out;
+            }
+        }        
+    }
+out:
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, rv, p, "read chain file %s, found %d certs", 
+                  fname, certs? certs->nelts : 0);
+    *pcerts = (APR_SUCCESS == rv)? certs : NULL;
+    return rv;
+}
+
+apr_status_t md_chain_fsave(apr_array_header_t *certs, apr_pool_t *p, 
+                            const char *fname, apr_fileperms_t perms)
+{
+    FILE *f;
+    apr_status_t rv;
+    const md_cert_t *cert;
+    unsigned long err = 0;
+    int i;
+    
+    rv = md_util_fopen(&f, fname, "w");
+    if (rv == APR_SUCCESS) {
+        apr_file_perms_set(fname, perms);
+        ERR_clear_error();
+        for (i = 0; i < certs->nelts; ++i) {
+            cert = APR_ARRAY_IDX(certs, i, const md_cert_t *);
+            assert(cert->x509);
+            
+            PEM_write_X509(f, cert->x509);
+            
+            if (0 < (err = ERR_get_error())) {
+                break;
+            }
+            
+        }
+        rv = fclose(f);
+        if (err) {
+            rv = APR_EINVAL;
+        }
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* certificate signing requests */
+
+static const char *alt_name(const char *domain, apr_pool_t *p)
+{
+    return apr_psprintf(p, "DNS:%s", domain);
+}
+
+static const char *alt_names(apr_array_header_t *domains, apr_pool_t *p)
+{
+    const char *alts = "", *sep = "", *domain;
+    int i;
+    
+    for (i = 0; i < domains->nelts; ++i) {
+        domain = APR_ARRAY_IDX(domains, i, const char *);
+        alts = apr_psprintf(p, "%s%sDNS:%s", alts, sep, domain);
+        sep = ",";
+    }
+    return alts;
+}
+
+static apr_status_t add_ext(X509 *x, int nid, const char *value, apr_pool_t *p)
+{
+    X509_EXTENSION *ext = NULL;
+    X509V3_CTX ctx;
+    apr_status_t rv;
+
+    X509V3_set_ctx_nodb(&ctx);
+    X509V3_set_ctx(&ctx, x, x, NULL, NULL, 0);
+    if (NULL == (ext = X509V3_EXT_conf_nid(NULL, &ctx, nid, (char*)value))) {
+        return APR_EGENERAL;
+    }
+    
+    ERR_clear_error();
+    rv = X509_add_ext(x, ext, -1)? APR_SUCCESS : APR_EINVAL;
+    if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "add_ext nid=%dd value='%s'", 
+                      nid, value); 
+        
+    }
+    X509_EXTENSION_free(ext);
+    return rv;
+}
+
+static apr_status_t sk_add_alt_names(STACK_OF(X509_EXTENSION) *exts,
+                                     apr_array_header_t *domains, apr_pool_t *p)
+{
+    if (domains->nelts > 0) {
+        X509_EXTENSION *x;
+        
+        x = X509V3_EXT_conf_nid(NULL, NULL, NID_subject_alt_name, (char*)alt_names(domains, p));
+        if (NULL == x) {
+            return APR_EGENERAL;
+        }
+        sk_X509_EXTENSION_push(exts, x);
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t add_must_staple(STACK_OF(X509_EXTENSION) *exts, const md_t *md, apr_pool_t *p)
+{
+    
+    if (md->must_staple) {
+        X509_EXTENSION *x = X509V3_EXT_conf_nid(NULL, NULL, 
+                                                NID_tlsfeature, (char*)"DER:30:03:02:01:05");
+        if (NULL == x) {
+            return APR_EGENERAL;
+        }
+        sk_X509_EXTENSION_push(exts, x);
+    }
+    return APR_SUCCESS;
+}
+
+apr_status_t md_cert_req_create(const char **pcsr_der_64, const md_t *md, 
+                                md_pkey_t *pkey, apr_pool_t *p)
+{
+    const char *s, *csr_der, *csr_der_64 = NULL;
+    const unsigned char *domain;
+    X509_REQ *csr;
+    X509_NAME *n = NULL;
+    STACK_OF(X509_EXTENSION) *exts = NULL;
+    apr_status_t rv;
+    int csr_der_len;
+    
+    assert(md->domains->nelts > 0);
+    
+    if (NULL == (csr = X509_REQ_new()) 
+        || NULL == (exts = sk_X509_EXTENSION_new_null())
+        || NULL == (n = X509_NAME_new())) {
+        rv = APR_ENOMEM;
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: openssl alloc X509 things", md->name);
+        goto out; 
+    }
+
+    /* subject name == first domain */
+    domain = APR_ARRAY_IDX(md->domains, 0, const unsigned char *);
+    if (!X509_NAME_add_entry_by_txt(n, "CN", MBSTRING_ASC, domain, -1, -1, 0)
+        || !X509_REQ_set_subject_name(csr, n)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "%s: REQ name add entry", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    /* collect extensions, such as alt names and must staple */
+    if (APR_SUCCESS != (rv = sk_add_alt_names(exts, md->domains, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: collecting alt names", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    if (APR_SUCCESS != (rv = add_must_staple(exts, md, p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: must staple", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    /* add extensions to csr */
+    if (sk_X509_EXTENSION_num(exts) > 0 && !X509_REQ_add_extensions(csr, exts)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: adding exts", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    /* add our key */
+    if (!X509_REQ_set_pubkey(csr, pkey->pkey)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: set pkey in csr", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    /* sign, der encode and base64url encode */
+    if (!X509_REQ_sign(csr, pkey->pkey, EVP_sha256())) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: sign csr", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    if ((csr_der_len = i2d_X509_REQ(csr, NULL)) < 0) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: der length", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    s = csr_der = apr_pcalloc(p, csr_der_len + 1);
+    if (i2d_X509_REQ(csr, (unsigned char**)&s) != csr_der_len) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: csr der enc", md->name);
+        rv = APR_EGENERAL; goto out;
+    }
+    csr_der_64 = md_util_base64url_encode(csr_der, csr_der_len, p);
+    rv = APR_SUCCESS;
+    
+out:
+    if (exts) {
+        sk_X509_EXTENSION_pop_free(exts, X509_EXTENSION_free);
+    }
+    if (csr) {
+        X509_REQ_free(csr);
+    }
+    if (n) {
+        X509_NAME_free(n);
+    }
+    *pcsr_der_64 = (APR_SUCCESS == rv)? csr_der_64 : NULL;
+    return rv;
+}
+
+apr_status_t md_cert_self_sign(md_cert_t **pcert, const char *cn, 
+                               const char *domain, md_pkey_t *pkey,
+                               apr_interval_time_t valid_for, apr_pool_t *p)
+{
+    X509 *x;
+    X509_NAME *n = NULL;
+    md_cert_t *cert = NULL;
+    apr_status_t rv;
+    int days;
+    BIGNUM *big_rnd = NULL;
+    ASN1_INTEGER *asn1_rnd = NULL;
+    unsigned char rnd[20];
+    
+    assert(domain);
+    
+    if (NULL == (x = X509_new()) 
+        || NULL == (n = X509_NAME_new())) {
+        rv = APR_ENOMEM;
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "%s: openssl alloc X509 things", domain);
+        goto out; 
+    }
+    
+    if (APR_SUCCESS != (rv = md_rand_bytes(rnd, sizeof(rnd), p))
+        || !(big_rnd = BN_bin2bn(rnd, sizeof(rnd), NULL))
+        || !(asn1_rnd = BN_to_ASN1_INTEGER(big_rnd, NULL))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "%s: setup random serial", domain);
+        rv = APR_EGENERAL; goto out;
+    } 
+    if (!X509_set_serialNumber(x, asn1_rnd)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "%s: set serial number", domain);
+        rv = APR_EGENERAL; goto out;
+    }
+    /* set common name and issue */
+    if (!X509_NAME_add_entry_by_txt(n, "CN", MBSTRING_ASC, (const unsigned char*)cn, -1, -1, 0)
+        || !X509_set_subject_name(x, n)
+        || !X509_set_issuer_name(x, n)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "%s: name add entry", domain);
+        rv = APR_EGENERAL; goto out;
+    }
+    /* cert are uncontrained (but not very trustworthy) */
+    if (APR_SUCCESS != (rv = add_ext(x, NID_basic_constraints, "CA:TRUE, pathlen:0", p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: set basic constraints ext", domain);
+        goto out;
+    }
+    /* add the domain as alt name */
+    if (APR_SUCCESS != (rv = add_ext(x, NID_subject_alt_name, alt_name(domain, p), p))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: set alt_name ext", domain);
+        goto out;
+    }
+    /* add our key */
+    if (!X509_set_pubkey(x, pkey->pkey)) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: set pkey in x509", domain);
+        rv = APR_EGENERAL; goto out;
+    }
+    
+    days = ((apr_time_sec(valid_for) + MD_SECS_PER_DAY - 1)/ MD_SECS_PER_DAY);
+    if (!X509_set_notBefore(x, ASN1_TIME_set(NULL, time(NULL)))) {
+        rv = APR_EGENERAL; goto out;
+    }
+    if (!X509_set_notAfter(x, ASN1_TIME_adj(NULL, time(NULL), days, 0))) {
+        rv = APR_EGENERAL; goto out;
+    }
+
+    /* sign with same key */
+    if (!X509_sign(x, pkey->pkey, EVP_sha256())) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "%s: sign x509", domain);
+        rv = APR_EGENERAL; goto out;
+    }
+
+    cert = make_cert(p, x);
+    rv = APR_SUCCESS;
+    
+out:
+    if (!cert && x) {
+        X509_free(x);
+    }
+    if (n) {
+        X509_NAME_free(n);
+    }
+    if (big_rnd) {
+        BN_free(big_rnd);
+    }
+    if (asn1_rnd) {
+        ASN1_INTEGER_free(asn1_rnd);
+    }
+    *pcert = (APR_SUCCESS == rv)? cert : NULL;
+    return rv;
+}
+
diff --git a/modules/md/md_crypt.h b/modules/md/md_crypt.h
new file mode 100644
index 0000000000..6f5c98826c
--- /dev/null
+++ b/modules/md/md_crypt.h
@@ -0,0 +1,110 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_crypt_h
+#define mod_md_md_crypt_h
+
+#include <apr_file_io.h>
+
+struct apr_array_header_t;
+struct md_t;
+struct md_http_response_t;
+struct md_cert_t;
+struct md_pkey_t;
+
+/**************************************************************************************************/
+/* random */
+
+apr_status_t md_rand_bytes(unsigned char *buf, apr_size_t len, apr_pool_t *p);
+
+/**************************************************************************************************/
+/* digests */
+apr_status_t md_crypt_sha256_digest64(const char **pdigest64, apr_pool_t *p, 
+                                      const char *d, size_t dlen);
+apr_status_t md_crypt_sha256_digest_hex(const char **pdigesthex, apr_pool_t *p, 
+                                        const char *d, size_t dlen);
+
+/**************************************************************************************************/
+/* private keys */
+
+typedef struct md_pkey_t md_pkey_t;
+
+apr_status_t md_crypt_init(apr_pool_t *pool);
+
+apr_status_t md_pkey_gen_rsa(md_pkey_t **ppkey, apr_pool_t *p, int bits);
+void md_pkey_free(md_pkey_t *pkey);
+
+const char *md_pkey_get_rsa_e64(md_pkey_t *pkey, apr_pool_t *p);
+const char *md_pkey_get_rsa_n64(md_pkey_t *pkey, apr_pool_t *p);
+
+apr_status_t md_pkey_fload(md_pkey_t **ppkey, apr_pool_t *p, 
+                           const char *pass_phrase, apr_size_t pass_len,
+                           const char *fname);
+apr_status_t md_pkey_fsave(md_pkey_t *pkey, apr_pool_t *p, 
+                           const char *pass_phrase, apr_size_t pass_len, 
+                           const char *fname, apr_fileperms_t perms);
+
+apr_status_t md_crypt_sign64(const char **psign64, md_pkey_t *pkey, apr_pool_t *p, 
+                             const char *d, size_t dlen);
+
+void *md_cert_get_X509(struct md_cert_t *cert);
+void *md_pkey_get_EVP_PKEY(struct md_pkey_t *pkey);
+
+/**************************************************************************************************/
+/* X509 certificates */
+
+typedef struct md_cert_t md_cert_t;
+
+typedef enum {
+    MD_CERT_UNKNOWN,
+    MD_CERT_VALID,
+    MD_CERT_EXPIRED
+} md_cert_state_t;
+
+void md_cert_free(md_cert_t *cert);
+
+apr_status_t md_cert_fload(md_cert_t **pcert, apr_pool_t *p, const char *fname);
+apr_status_t md_cert_fsave(md_cert_t *cert, apr_pool_t *p, 
+                           const char *fname, apr_fileperms_t perms);
+
+apr_status_t md_cert_read_http(md_cert_t **pcert, apr_pool_t *pool, 
+                               const struct md_http_response_t *res);
+
+md_cert_state_t md_cert_state_get(md_cert_t *cert);
+int md_cert_is_valid_now(const md_cert_t *cert);
+int md_cert_has_expired(const md_cert_t *cert);
+int md_cert_covers_domain(md_cert_t *cert, const char *domain_name);
+int md_cert_covers_md(md_cert_t *cert, const struct md_t *md);
+apr_time_t md_cert_get_not_after(md_cert_t *cert);
+
+apr_status_t md_cert_get_issuers_uri(const char **puri, md_cert_t *cert, apr_pool_t *p);
+apr_status_t md_cert_get_alt_names(apr_array_header_t **pnames, md_cert_t *cert, apr_pool_t *p);
+
+apr_status_t md_cert_to_base64url(const char **ps64, md_cert_t *cert, apr_pool_t *p);
+apr_status_t md_cert_from_base64url(md_cert_t **pcert, const char *s64, apr_pool_t *p);
+
+apr_status_t md_chain_fload(struct apr_array_header_t **pcerts, 
+                            apr_pool_t *p, const char *fname);
+apr_status_t md_chain_fsave(struct apr_array_header_t *certs, 
+                            apr_pool_t *p, const char *fname, apr_fileperms_t perms);
+
+apr_status_t md_cert_req_create(const char **pcsr_der_64, const struct md_t *md, 
+                                md_pkey_t *pkey, apr_pool_t *p);
+
+apr_status_t md_cert_self_sign(md_cert_t **pcert, const char *cn, 
+                               const char *domain, md_pkey_t *pkey,
+                               apr_interval_time_t valid_for, apr_pool_t *p);
+
+#endif /* md_crypt_h */
diff --git a/modules/md/md_curl.c b/modules/md/md_curl.c
new file mode 100644
index 0000000000..1eb5e554c0
--- /dev/null
+++ b/modules/md/md_curl.c
@@ -0,0 +1,301 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+
+#include <curl/curl.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_buckets.h>
+
+#include "md_http.h"
+#include "md_log.h"
+#include "md_curl.h"
+
+/**************************************************************************************************/
+/* md_http curl implementation */
+
+
+static apr_status_t curl_status(int curl_code)
+{
+    switch (curl_code) {
+        case CURLE_OK:                   return APR_SUCCESS;
+        case CURLE_UNSUPPORTED_PROTOCOL: return APR_ENOTIMPL; 
+        case CURLE_NOT_BUILT_IN:         return APR_ENOTIMPL; 
+        case CURLE_URL_MALFORMAT:        return APR_EINVAL;
+        case CURLE_COULDNT_RESOLVE_PROXY:return APR_ECONNREFUSED;
+        case CURLE_COULDNT_RESOLVE_HOST: return APR_ECONNREFUSED;
+        case CURLE_COULDNT_CONNECT:      return APR_ECONNREFUSED;
+        case CURLE_REMOTE_ACCESS_DENIED: return APR_EACCES;
+        case CURLE_OUT_OF_MEMORY:        return APR_ENOMEM;
+        case CURLE_OPERATION_TIMEDOUT:   return APR_TIMEUP;
+        case CURLE_SSL_CONNECT_ERROR:    return APR_ECONNABORTED;
+        case CURLE_AGAIN:                return APR_EAGAIN;
+        default:                         return APR_EGENERAL;
+    }
+}
+
+static size_t req_data_cb(void *data, size_t len, size_t nmemb, void *baton)
+{
+    apr_bucket_brigade *body = baton;
+    size_t blen, read_len = 0, max_len = len * nmemb;
+    const char *bdata;
+    apr_bucket *b;
+    apr_status_t rv;
+    
+    while (body && !APR_BRIGADE_EMPTY(body) && max_len > 0) {
+        b = APR_BRIGADE_FIRST(body);
+        if (APR_BUCKET_IS_METADATA(b)) {
+            if (APR_BUCKET_IS_EOS(b)) {
+                body = NULL;
+            }
+        }
+        else {
+            rv = apr_bucket_read(b, &bdata, &blen, APR_BLOCK_READ);
+            if (rv == APR_SUCCESS) {
+                if (blen > max_len) {
+                    apr_bucket_split(b, max_len);
+                    blen = max_len;
+                }
+                memcpy(data, bdata, blen);
+                read_len += blen;
+                max_len -= blen;
+            }
+            else {
+                body = NULL;
+                if (!APR_STATUS_IS_EOF(rv)) {
+                    /* everything beside EOF is an error */
+                    read_len = CURL_READFUNC_ABORT;
+                }
+            }
+            
+        }
+        apr_bucket_delete(b);
+    }
+    
+    return read_len;
+}
+
+static size_t resp_data_cb(void *data, size_t len, size_t nmemb, void *baton)
+{
+    md_http_response_t *res = baton;
+    size_t blen = len * nmemb;
+    apr_status_t rv;
+    
+    if (res->body) {
+        if (res->req->resp_limit) {
+            apr_off_t body_len = 0;
+            apr_brigade_length(res->body, 0, &body_len);
+            if (body_len + len > res->req->resp_limit) {
+                return 0; /* signal curl failure */
+            }
+        }
+        rv = apr_brigade_write(res->body, NULL, NULL, (const char *)data, blen);
+        if (rv != APR_SUCCESS) {
+            /* returning anything != blen will make CURL fail this */
+            return 0;
+        }
+    }
+    return blen;
+}
+
+static size_t header_cb(void *buffer, size_t elen, size_t nmemb, void *baton)
+{
+    md_http_response_t *res = baton;
+    size_t len, clen = elen * nmemb;
+    const char *name = NULL, *value = "", *b = buffer;
+    int i;
+    
+    len = (clen && b[clen-1] == '\n')? clen-1 : clen;
+    len = (len && b[len-1] == '\r')? len-1 : len;
+    for (i = 0; i < len; ++i) {
+        if (b[i] == ':') {
+            name = apr_pstrndup(res->req->pool, b, i);
+            ++i;
+            while (i < len && b[i] == ' ') {
+                ++i;
+            }
+            if (i < len) {
+                value = apr_pstrndup(res->req->pool, b+i, len - i);
+            }
+            break;
+        }
+    }
+    
+    if (name != NULL) {
+        apr_table_add(res->headers, name, value);
+    }
+    return clen;
+}
+
+static apr_status_t curl_init(md_http_request_t *req)
+{
+    CURL *curl = curl_easy_init();
+    if (!curl) {
+        return APR_EGENERAL;
+    }
+    
+    curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, header_cb);
+    curl_easy_setopt(curl, CURLOPT_HEADERDATA, NULL);
+    curl_easy_setopt(curl, CURLOPT_READFUNCTION, req_data_cb);
+    curl_easy_setopt(curl, CURLOPT_READDATA, NULL);
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, resp_data_cb);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, NULL);
+    
+    req->internals = curl;
+    return APR_SUCCESS;
+}
+
+typedef struct {
+    md_http_request_t *req;
+    struct curl_slist *hdrs;
+    apr_status_t rv;
+} curlify_hdrs_ctx;
+
+static int curlify_headers(void *baton, const char *key, const char *value)
+{
+    curlify_hdrs_ctx *ctx = baton;
+    const char *s;
+    
+    if (strchr(key, '\r') || strchr(key, '\n')
+        || strchr(value, '\r') || strchr(value, '\n')) {
+        ctx->rv = APR_EINVAL;
+        return 0;
+    }
+    s = apr_psprintf(ctx->req->pool, "%s: %s", key, value);
+    ctx->hdrs = curl_slist_append(ctx->hdrs, s);
+    return 1;
+}
+
+static apr_status_t curl_perform(md_http_request_t *req)
+{
+    apr_status_t rv = APR_SUCCESS;
+    int curle;
+    md_http_response_t *res;
+    CURL *curl;
+    struct curl_slist *req_hdrs = NULL;
+
+    rv = curl_init(req);
+    curl = req->internals;
+    
+    res = apr_pcalloc(req->pool, sizeof(*res));
+    
+    res->req = req;
+    res->rv = APR_SUCCESS;
+    res->status = 400;
+    res->headers = apr_table_make(req->pool, 5);
+    res->body = apr_brigade_create(req->pool, req->bucket_alloc);
+    
+    curl_easy_setopt(curl, CURLOPT_URL, req->url);
+    if (!apr_strnatcasecmp("GET", req->method)) {
+        /* nop */
+    }
+    else if (!apr_strnatcasecmp("HEAD", req->method)) {
+        curl_easy_setopt(curl, CURLOPT_NOBODY, 1L);
+    }
+    else if (!apr_strnatcasecmp("POST", req->method)) {
+        curl_easy_setopt(curl, CURLOPT_POST, 1L);
+    }
+    else {
+        curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, req->method);
+    }
+    curl_easy_setopt(curl, CURLOPT_HEADERDATA, res);
+    curl_easy_setopt(curl, CURLOPT_READDATA, req->body);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, res);
+    
+    if (req->user_agent) {
+        curl_easy_setopt(curl, CURLOPT_USERAGENT, req->user_agent);
+    }
+    if (!apr_is_empty_table(req->headers)) {
+        curlify_hdrs_ctx ctx;
+        
+        ctx.req = req;
+        ctx.hdrs = NULL;
+        ctx.rv = APR_SUCCESS;
+        apr_table_do(curlify_headers, &ctx, req->headers, NULL);
+        req_hdrs = ctx.hdrs;
+        if (ctx.rv == APR_SUCCESS) {
+            curl_easy_setopt(curl, CURLOPT_HTTPHEADER, req_hdrs);
+        }
+    }
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, req->pool, 
+                  "request %ld --> %s %s", req->id, req->method, req->url);
+    
+    if (md_log_is_level(req->pool, MD_LOG_TRACE3)) {
+        curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+    }
+    
+    curle = curl_easy_perform(curl);
+    res->rv = curl_status(curle);
+    
+    if (APR_SUCCESS == res->rv) {
+        long l;
+        res->rv = curl_status(curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &l));
+        if (APR_SUCCESS == res->rv) {
+            res->status = (int)l;
+        }
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, res->rv, req->pool, 
+                      "request %ld <-- %d", req->id, res->status);
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, res->rv, req->pool, 
+                      "request %ld failed(%d): %s", req->id, curle, curl_easy_strerror(curle));
+    }
+    
+    if (req->cb) {
+        res->rv = req->cb(res);
+    }
+    
+    rv = res->rv;
+    md_http_req_destroy(req);
+    if (req_hdrs) {
+        curl_slist_free_all(req_hdrs);
+    }
+    
+    return rv;
+}
+
+static int initialized;
+
+static apr_status_t md_curl_init(void) {
+    if (!initialized) {
+        initialized = 1;
+        curl_global_init(CURL_GLOBAL_DEFAULT);
+    }
+    return APR_SUCCESS;
+}
+
+static void curl_req_cleanup(md_http_request_t *req) 
+{
+    if (req->internals) {
+        curl_easy_cleanup(req->internals);
+        req->internals = NULL;
+    }
+}
+
+static md_http_impl_t impl = {
+    md_curl_init,
+    curl_req_cleanup,
+    curl_perform
+};
+
+md_http_impl_t * md_curl_get_impl(apr_pool_t *p)
+{
+    /* trigger early global curl init, before we are down a rabbit hole */
+    md_curl_init();
+    return &impl;
+}
diff --git a/modules/md/md_curl.h b/modules/md/md_curl.h
new file mode 100644
index 0000000000..5b358cbdd9
--- /dev/null
+++ b/modules/md/md_curl.h
@@ -0,0 +1,23 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef md_curl_h
+#define md_curl_h
+
+struct md_http_impl;
+
+struct md_http_impl_t * md_curl_get_impl(apr_pool_t *p);
+
+#endif /* md_curl_h */
diff --git a/modules/md/md_http.c b/modules/md/md_http.c
new file mode 100644
index 0000000000..984066d9e1
--- /dev/null
+++ b/modules/md/md_http.c
@@ -0,0 +1,237 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_buckets.h>
+
+#include "md_http.h"
+#include "md_log.h"
+
+struct md_http_t {
+    apr_pool_t *pool;
+    apr_bucket_alloc_t *bucket_alloc;
+    apr_off_t resp_limit;
+    md_http_impl_t *impl;
+    const char *user_agent;
+};
+
+static md_http_impl_t *cur_impl;
+static int cur_init_done;
+
+void md_http_use_implementation(md_http_impl_t *impl)
+{
+    if (cur_impl != impl) {
+        cur_impl = impl;
+        cur_init_done = 0;
+    }
+}
+
+static long next_req_id;
+
+apr_status_t md_http_create(md_http_t **phttp, apr_pool_t *p, const char *user_agent)
+{
+    md_http_t *http;
+    apr_status_t rv = APR_SUCCESS;
+
+    if (!cur_impl) {
+        *phttp = NULL;
+        return APR_ENOTIMPL;
+    }
+    
+    if (!cur_init_done) {
+        if (APR_SUCCESS == (rv = cur_impl->init())) {
+            cur_init_done = 1;
+        }
+        else {
+            return rv;
+        }
+    }
+    
+    http = apr_pcalloc(p, sizeof(*http));
+    http->pool = p;
+    http->impl = cur_impl;
+    http->user_agent = apr_pstrdup(p, user_agent);
+    http->bucket_alloc = apr_bucket_alloc_create(p);
+    if (!http->bucket_alloc) {
+        return APR_EGENERAL;
+    }
+    *phttp = http;
+    return APR_SUCCESS;
+}
+
+void md_http_set_response_limit(md_http_t *http, apr_off_t resp_limit)
+{
+    http->resp_limit = resp_limit;
+}
+
+static apr_status_t req_create(md_http_request_t **preq, md_http_t *http, 
+                               const char *method, const char *url, struct apr_table_t *headers,
+                               md_http_cb *cb, void *baton)
+{
+    md_http_request_t *req;
+    apr_pool_t *pool;
+    apr_status_t rv;
+    
+    rv = apr_pool_create(&pool, http->pool);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    
+    req = apr_pcalloc(pool, sizeof(*req));
+    req->id = next_req_id++;
+    req->pool = pool;
+    req->bucket_alloc = http->bucket_alloc;
+    req->http = http;
+    req->method = method;
+    req->url = url;
+    req->headers = headers? apr_table_copy(req->pool, headers) : apr_table_make(req->pool, 5);
+    req->resp_limit = http->resp_limit;
+    req->cb = cb;
+    req->baton = baton;
+    req->user_agent = http->user_agent;
+
+    *preq = req;
+    return rv;
+}
+
+void md_http_req_destroy(md_http_request_t *req) 
+{
+    if (req->internals) {
+        req->http->impl->req_cleanup(req);
+        req->internals = NULL;
+    }
+    apr_pool_destroy(req->pool);
+}
+
+static apr_status_t schedule(md_http_request_t *req, 
+                             apr_bucket_brigade *body, int detect_clen,
+                             long *preq_id) 
+{
+    apr_status_t rv;
+    
+    req->body = body;
+    req->body_len = body? -1 : 0;
+
+    if (req->body && detect_clen) {
+        rv = apr_brigade_length(req->body, 1, &req->body_len);
+        if (rv != APR_SUCCESS) {
+            md_http_req_destroy(req);
+            return rv;
+        }
+    }
+    
+    if (req->body_len == 0 && apr_strnatcasecmp("GET", req->method)) {
+        apr_table_setn(req->headers, "Content-Length", "0");
+    }
+    else if (req->body_len > 0) {
+        apr_table_setn(req->headers, "Content-Length", apr_off_t_toa(req->pool, req->body_len));
+    }
+    
+    if (preq_id) {
+        *preq_id = req->id;
+    }
+    
+    /* we send right away */
+    rv = req->http->impl->perform(req);
+    
+    return rv;
+}
+
+apr_status_t md_http_GET(struct md_http_t *http, 
+                         const char *url, struct apr_table_t *headers,
+                         md_http_cb *cb, void *baton, long *preq_id)
+{
+    md_http_request_t *req;
+    apr_status_t rv;
+    
+    rv = req_create(&req, http, "GET", url, headers, cb, baton);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    
+    return schedule(req, NULL, 0, preq_id);
+}
+
+apr_status_t md_http_HEAD(struct md_http_t *http, 
+                          const char *url, struct apr_table_t *headers,
+                          md_http_cb *cb, void *baton, long *preq_id)
+{
+    md_http_request_t *req;
+    apr_status_t rv;
+    
+    rv = req_create(&req, http, "HEAD", url, headers, cb, baton);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    
+    return schedule(req, NULL, 0, preq_id);
+}
+
+apr_status_t md_http_POST(struct md_http_t *http, const char *url, 
+                          struct apr_table_t *headers, const char *content_type, 
+                          apr_bucket_brigade *body,
+                          md_http_cb *cb, void *baton, long *preq_id)
+{
+    md_http_request_t *req;
+    apr_status_t rv;
+    
+    rv = req_create(&req, http, "POST", url, headers, cb, baton);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    
+    if (content_type) {
+        apr_table_set(req->headers, "Content-Type", content_type); 
+    }
+    return schedule(req, body, 1, preq_id);
+}
+
+apr_status_t md_http_POSTd(md_http_t *http, const char *url, 
+                           struct apr_table_t *headers, const char *content_type, 
+                           const char *data, size_t data_len, 
+                           md_http_cb *cb, void *baton, long *preq_id)
+{
+    md_http_request_t *req;
+    apr_status_t rv;
+    apr_bucket_brigade *body = NULL;
+    
+    rv = req_create(&req, http, "POST", url, headers, cb, baton);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+
+    if (data && data_len > 0) {
+        body = apr_brigade_create(req->pool, req->http->bucket_alloc);
+        rv = apr_brigade_write(body, NULL, NULL, data, data_len);
+        if (rv != APR_SUCCESS) {
+            md_http_req_destroy(req);
+            return rv;
+        }
+    }
+    
+    if (content_type) {
+        apr_table_set(req->headers, "Content-Type", content_type); 
+    }
+     
+    return schedule(req, body, 1, preq_id);
+}
+
+apr_status_t md_http_await(md_http_t *http, long req_id)
+{
+    return APR_SUCCESS;
+}
+
diff --git a/modules/md/md_http.h b/modules/md/md_http.h
new file mode 100644
index 0000000000..e6810b9da7
--- /dev/null
+++ b/modules/md/md_http.h
@@ -0,0 +1,99 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_http_h
+#define mod_md_md_http_h
+
+struct apr_table_t;
+struct apr_bucket_brigade;
+struct apr_bucket_alloc_t;
+
+typedef struct md_http_t md_http_t;
+
+typedef struct md_http_request_t md_http_request_t;
+typedef struct md_http_response_t md_http_response_t;
+
+typedef apr_status_t md_http_cb(const md_http_response_t *res);
+
+struct md_http_request_t {
+    long id;
+    md_http_t *http;
+    apr_pool_t *pool;
+    struct apr_bucket_alloc_t *bucket_alloc;
+    const char *method;
+    const char *url;
+    const char *user_agent;
+    apr_table_t *headers;
+    struct apr_bucket_brigade *body;
+    apr_off_t body_len;
+    apr_off_t resp_limit;
+    md_http_cb *cb;
+    void *baton;
+    void *internals;
+};
+
+struct md_http_response_t {
+    md_http_request_t *req;
+    apr_status_t rv;
+    int status;
+    apr_table_t *headers;
+    struct apr_bucket_brigade *body;
+};
+
+apr_status_t md_http_create(md_http_t **phttp, apr_pool_t *p, const char *user_agent);
+
+void md_http_set_response_limit(md_http_t *http, apr_off_t resp_limit);
+
+apr_status_t md_http_GET(md_http_t *http, 
+                         const char *url, struct apr_table_t *headers,
+                         md_http_cb *cb, void *baton, long *preq_id);
+
+apr_status_t md_http_HEAD(md_http_t *http, 
+                          const char *url, struct apr_table_t *headers,
+                          md_http_cb *cb, void *baton, long *preq_id);
+
+apr_status_t md_http_POST(md_http_t *http, const char *url, 
+                          struct apr_table_t *headers, const char *content_type, 
+                          struct apr_bucket_brigade *body,
+                          md_http_cb *cb, void *baton, long *preq_id);
+
+apr_status_t md_http_POSTd(md_http_t *http, const char *url, 
+                           struct apr_table_t *headers, const char *content_type, 
+                           const char *data, size_t data_len, 
+                           md_http_cb *cb, void *baton, long *preq_id);
+
+apr_status_t md_http_await(md_http_t *http, long req_id);
+
+void md_http_req_destroy(md_http_request_t *req);
+
+/**************************************************************************************************/
+/* interface to implementation */
+
+typedef apr_status_t md_http_init_cb(void);
+typedef void md_http_req_cleanup_cb(md_http_request_t *req);
+typedef apr_status_t md_http_perform_cb(md_http_request_t *req);
+
+typedef struct md_http_impl_t md_http_impl_t;
+struct md_http_impl_t {
+    md_http_init_cb *init;
+    md_http_req_cleanup_cb *req_cleanup;
+    md_http_perform_cb *perform;
+};
+
+void md_http_use_implementation(md_http_impl_t *impl);
+
+
+
+#endif /* md_http_h */
diff --git a/modules/md/md_json.c b/modules/md/md_json.c
new file mode 100644
index 0000000000..fc7b13f8de
--- /dev/null
+++ b/modules/md/md_json.c
@@ -0,0 +1,1016 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_buckets.h>
+
+#include "md_json.h"
+#include "md_log.h"
+#include "md_http.h"
+#include "md_util.h"
+
+/* jansson thinks everyone compiles with the platform's cc in its fullest capabilities
+ * when undefining their INLINEs, we get static, unused functions, arg 
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunknown-pragmas"
+#pragma GCC diagnostic ignored "-Wunreachable-code"
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+
+#include <jansson_config.h>
+#undef   JSON_INLINE
+#define JSON_INLINE 
+#include <jansson.h>
+
+#pragma clang diagnostic pop
+#pragma GCC diagnostic pop
+
+struct md_json_t {
+    apr_pool_t *p;
+    json_t *j;
+};
+
+/**************************************************************************************************/
+/* lifecylce */
+
+static apr_status_t json_pool_cleanup(void *data)
+{
+    md_json_t *json = data;
+    if (json) {
+        md_json_destroy(json);
+    }
+    return APR_SUCCESS;
+}
+
+static md_json_t *json_create(apr_pool_t *pool, json_t *j)
+{
+    md_json_t *json;
+    
+    if (!j) {
+        apr_abortfunc_t abfn = apr_pool_abort_get(pool);
+        if (abfn) {
+            abfn(APR_ENOMEM);
+        }
+        assert(j != NULL); /* failsafe in case abort is unset */
+    }
+    json = apr_pcalloc(pool, sizeof(*json));
+    json->p = pool;
+    json->j = j;
+    apr_pool_cleanup_register(pool, json, json_pool_cleanup, apr_pool_cleanup_null);
+        
+    return json;
+}
+
+md_json_t *md_json_create(apr_pool_t *pool)
+{
+    return json_create(pool, json_object());
+}
+
+md_json_t *md_json_create_s(apr_pool_t *pool, const char *s)
+{
+    return json_create(pool, json_string(s));
+}
+
+void md_json_destroy(md_json_t *json)
+{
+    if (json && json->j) {
+        json_decref(json->j);
+        json->j = NULL;
+    }
+}
+
+md_json_t *md_json_copy(apr_pool_t *pool, md_json_t *json)
+{
+    return json_create(pool, json_copy(json->j));
+}
+
+md_json_t *md_json_clone(apr_pool_t *pool, md_json_t *json)
+{
+    return json_create(pool, json_deep_copy(json->j));
+}
+
+/**************************************************************************************************/
+/* selectors */
+
+
+static json_t *jselect(md_json_t *json, va_list ap)
+{
+    json_t *j;
+    const char *key;
+    
+    j = json->j;
+    key = va_arg(ap, char *);
+    while (key && j) {
+        j = json_object_get(j, key);
+        key = va_arg(ap, char *);
+    }
+    return j;
+}
+
+static json_t *jselect_parent(const char **child_key, int create, md_json_t *json, va_list ap)
+{
+    const char *key, *next;
+    json_t *j, *jn;
+    
+    *child_key = NULL;
+    j = json->j;
+    key = va_arg(ap, char *);
+    while (key && j) {
+        next = va_arg(ap, char *);
+        if (next) {
+            jn = json_object_get(j, key);
+            if (!jn && create) {
+                jn = json_object();
+                json_object_set_new(j, key, jn);
+            }
+            j = jn;
+        }
+        else {
+            *child_key = key;
+        }
+        key = next;
+    }
+    return j;
+}
+
+static apr_status_t jselect_add(json_t *val, md_json_t *json, va_list ap)
+{
+    const char *key;
+    json_t *j, *aj;
+    
+    j = jselect_parent(&key, 1, json, ap);
+    
+    if (!j || !json_is_object(j)) {
+        json_decref(val);
+        return APR_EINVAL;
+    }
+    
+    aj = json_object_get(j, key);
+    if (!aj) {
+        aj = json_array();
+        json_object_set_new(j, key, aj);
+    }
+    
+    if (!json_is_array(aj)) {
+        json_decref(val);
+        return APR_EINVAL;
+    }
+
+    json_array_append(aj, val);
+    return APR_SUCCESS;
+}
+
+static apr_status_t jselect_set(json_t *val, md_json_t *json, va_list ap)
+{
+    const char *key;
+    json_t *j;
+    
+    j = jselect_parent(&key, 1, json, ap);
+    
+    if (!j) {
+        json_decref(val);
+        return APR_EINVAL;
+    }
+    
+    if (key) {
+        if (!json_is_object(j)) {
+            json_decref(val);
+            return APR_EINVAL;
+        }
+        json_object_set(j, key, val);
+    }
+    else {
+        /* replace */
+        if (json->j) {
+            json_decref(json->j);
+        }
+        json_incref(val);
+        json->j = val;
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t jselect_set_new(json_t *val, md_json_t *json, va_list ap)
+{
+    const char *key;
+    json_t *j;
+    
+    j = jselect_parent(&key, 1, json, ap);
+    
+    if (!j) {
+        json_decref(val);
+        return APR_EINVAL;
+    }
+    
+    if (key) {
+        if (!json_is_object(j)) {
+            json_decref(val);
+            return APR_EINVAL;
+        }
+        json_object_set_new(j, key, val);
+    }
+    else {
+        /* replace */
+        if (json->j) {
+            json_decref(json->j);
+        }
+        json->j = val;
+    }
+    return APR_SUCCESS;
+}
+
+int md_json_has_key(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    return j != NULL;
+}
+
+/**************************************************************************************************/
+/* booleans */
+
+int md_json_getb(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    return j? json_is_true(j) : 0;
+}
+
+apr_status_t md_json_setb(int value, md_json_t *json, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    
+    va_start(ap, json);
+    rv = jselect_set_new(json_boolean(value), json, ap);
+    va_end(ap);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* numbers */
+
+double md_json_getn(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    return (j && json_is_number(j))? json_number_value(j) : 0.0;
+}
+
+apr_status_t md_json_setn(double value, md_json_t *json, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    
+    va_start(ap, json);
+    rv = jselect_set_new(json_real(value), json, ap);
+    va_end(ap);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* longs */
+
+long md_json_getl(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    return (long)((j && json_is_number(j))? json_integer_value(j) : 0L);
+}
+
+apr_status_t md_json_setl(long value, md_json_t *json, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    
+    va_start(ap, json);
+    rv = jselect_set_new(json_integer(value), json, ap);
+    va_end(ap);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* strings */
+
+const char *md_json_gets(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    return (j && json_is_string(j))? json_string_value(j) : NULL;
+}
+
+const char *md_json_dups(apr_pool_t *p, md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    return (j && json_is_string(j))? apr_pstrdup(p, json_string_value(j)) : NULL;
+}
+
+apr_status_t md_json_sets(const char *value, md_json_t *json, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    
+    va_start(ap, json);
+    rv = jselect_set_new(json_string(value), json, ap);
+    va_end(ap);
+    return rv;
+}
+
+/**************************************************************************************************/
+/* json itself */
+
+md_json_t *md_json_getj(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    
+    if (j) {
+        if (j == json->j) {
+            return json;
+        }
+        json_incref(j);
+        return json_create(json->p, j);
+    }
+    return NULL;
+}
+
+apr_status_t md_json_setj(md_json_t *value, md_json_t *json, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    const char *key;
+    json_t *j;
+    
+    if (value) {
+        va_start(ap, json);
+        rv = jselect_set(value->j, json, ap);
+        va_end(ap);
+    }
+    else {
+        va_start(ap, json);
+        j = jselect_parent(&key, 1, json, ap);
+        va_end(ap);
+        
+        if (key && j && !json_is_object(j)) {
+            json_object_del(j, key);
+            rv = APR_SUCCESS;
+        }
+        else {
+            rv = APR_EINVAL;
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_json_addj(md_json_t *value, md_json_t *json, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    
+    va_start(ap, json);
+    rv = jselect_add(value->j, json, ap);
+    va_end(ap);
+    return rv;
+}
+
+
+/**************************************************************************************************/
+/* arrays / objects */
+
+apr_status_t md_json_clr(md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    if (j && json_is_object(j)) {
+        json_object_clear(j);
+    }
+    else if (j && json_is_array(j)) {
+        json_array_clear(j);
+    }
+    return APR_SUCCESS;
+}
+
+apr_status_t md_json_del(md_json_t *json, ...)
+{
+    const char *key;
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect_parent(&key, 0, json, ap);
+    va_end(ap);
+    
+    if (key && j && json_is_object(j)) {
+        json_object_del(j, key);
+    }
+    return APR_SUCCESS;
+}
+
+/**************************************************************************************************/
+/* object strings */
+
+apr_status_t md_json_gets_dict(apr_table_t *dict, md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    if (j && json_is_object(j)) {
+        const char *key;
+        json_t *val;
+        
+        json_object_foreach(j, key, val) {
+            if (json_is_string(val)) {
+                apr_table_set(dict, key, json_string_value(val));
+            }
+        }
+        return APR_SUCCESS;
+    }
+    return APR_ENOENT;
+}
+
+static int object_set(void *data, const char *key, const char *val)
+{
+    json_t *j = data, *nj = json_string(val);
+    json_object_set(j, key, nj);
+    json_decref(nj);
+    return 1;
+}
+ 
+apr_status_t md_json_sets_dict(apr_table_t *dict, md_json_t *json, ...)
+{
+    json_t *nj, *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    
+    if (!j || !json_is_object(j)) {
+        const char *key;
+        
+        va_start(ap, json);
+        j = jselect_parent(&key, 1, json, ap);
+        va_end(ap);
+        
+        if (!key || !j || !json_is_object(j)) {
+            return APR_EINVAL;
+        }
+        nj = json_object();
+        json_object_set_new(j, key, nj);
+        j = nj; 
+    }
+    
+    apr_table_do(object_set, j, dict, NULL);
+    return APR_SUCCESS;
+}
+
+/**************************************************************************************************/
+/* conversions */
+
+apr_status_t md_json_pass_to(void *value, md_json_t *json, apr_pool_t *p, void *baton)
+{
+    (void)p;
+    (void)baton;
+    return md_json_setj(value, json, NULL);
+}
+
+apr_status_t md_json_pass_from(void **pvalue, md_json_t *json, apr_pool_t *p, void *baton)
+{
+    (void)p;
+    (void)baton;
+    *pvalue = json;
+    return APR_SUCCESS;
+}
+
+apr_status_t md_json_clone_to(void *value, md_json_t *json, apr_pool_t *p, void *baton)
+{
+    (void)baton;
+    return md_json_setj(md_json_clone(p, value), json, NULL);
+}
+
+apr_status_t md_json_clone_from(void **pvalue, md_json_t *json, apr_pool_t *p, void *baton)
+{
+    (void)baton;
+    *pvalue = md_json_clone(p, json);
+    return APR_SUCCESS;
+}
+
+/**************************************************************************************************/
+/* array generic */
+
+apr_status_t md_json_geta(apr_array_header_t *a, md_json_from_cb *cb, void *baton,
+                          md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    apr_status_t rv = APR_SUCCESS;
+    size_t index;
+    json_t *val;
+    md_json_t wrap;
+    void *element;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    
+    if (!j || !json_is_array(j)) {
+        return APR_ENOENT;
+    }
+        
+    wrap.p = a->pool;
+    json_array_foreach(j, index, val) {
+        wrap.j = val;
+        if (APR_SUCCESS == (rv = cb(&element, &wrap, wrap.p, baton))) {
+            if (element) {
+                APR_ARRAY_PUSH(a, void*) = element;
+            }
+        }
+        else if (APR_ENOENT == rv) {
+            rv = APR_SUCCESS;
+        }
+        else {
+            break;
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_json_seta(apr_array_header_t *a, md_json_to_cb *cb, void *baton, 
+                          md_json_t *json, ...)
+{
+    json_t *j, *nj;
+    md_json_t wrap;
+    apr_status_t rv = APR_SUCCESS;
+    va_list ap;
+    int i;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    
+    if (!j || !json_is_array(j)) {
+        const char *key;
+        
+        va_start(ap, json);
+        j = jselect_parent(&key, 1, json, ap);
+        va_end(ap);
+        
+        if (!key || !j || !json_is_object(j)) {
+            return APR_EINVAL;
+        }
+        nj = json_array();
+        json_object_set_new(j, key, nj);
+        j = nj; 
+    }
+    
+    json_array_clear(j);
+    wrap.p = json->p;
+    for (i = 0; i < a->nelts; ++i) {
+        if (!cb) {
+            return APR_EINVAL;
+        }    
+        wrap.j = json_string("");
+        if (APR_SUCCESS == (rv = cb(APR_ARRAY_IDX(a, i, void*), &wrap, json->p, baton))) {
+            json_array_append_new(j, wrap.j);
+        }
+    }
+    return rv;
+}
+
+int md_json_itera(md_json_itera_cb *cb, void *baton, md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    size_t index;
+    json_t *val;
+    md_json_t wrap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    
+    if (!j || !json_is_array(j)) {
+        return 0;
+    }
+        
+    wrap.p = json->p;
+    json_array_foreach(j, index, val) {
+        wrap.j = val;
+        if (!cb(baton, index, &wrap)) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+/**************************************************************************************************/
+/* array strings */
+
+apr_status_t md_json_getsa(apr_array_header_t *a, md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    if (j && json_is_array(j)) {
+        size_t index;
+        json_t *val;
+        
+        json_array_foreach(j, index, val) {
+            if (json_is_string(val)) {
+                APR_ARRAY_PUSH(a, const char *) = json_string_value(val);
+            }
+        }
+        return APR_SUCCESS;
+    }
+    return APR_ENOENT;
+}
+
+apr_status_t md_json_dupsa(apr_array_header_t *a, apr_pool_t *p, md_json_t *json, ...)
+{
+    json_t *j;
+    va_list ap;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+
+    if (j && json_is_array(j)) {
+        size_t index;
+        json_t *val;
+        
+        json_array_foreach(j, index, val) {
+            if (json_is_string(val)) {
+                APR_ARRAY_PUSH(a, const char *) = apr_pstrdup(p, json_string_value(val));
+            }
+        }
+        return APR_SUCCESS;
+    }
+    return APR_ENOENT;
+}
+
+apr_status_t md_json_setsa(apr_array_header_t *a, md_json_t *json, ...)
+{
+    json_t *nj, *j;
+    va_list ap;
+    int i;
+    
+    va_start(ap, json);
+    j = jselect(json, ap);
+    va_end(ap);
+    
+    if (!j || !json_is_array(j)) {
+        const char *key;
+        
+        va_start(ap, json);
+        j = jselect_parent(&key, 1, json, ap);
+        va_end(ap);
+        
+        if (!key || !j || !json_is_object(j)) {
+            return APR_EINVAL;
+        }
+        nj = json_array();
+        json_object_set_new(j, key, nj);
+        j = nj; 
+    }
+    
+    json_array_clear(j);
+    for (i = 0; i < a->nelts; ++i) {
+        json_array_append_new(j, json_string(APR_ARRAY_IDX(a, i, const char*)));
+    }
+    return APR_SUCCESS;
+}
+
+/**************************************************************************************************/
+/* formatting, parsing */
+
+typedef struct {
+    md_json_t *json;
+    md_json_fmt_t fmt;
+    const char *fname;
+    apr_file_t *f;
+} j_write_ctx;
+
+static int dump_cb(const char *buffer, size_t len, void *baton)
+{
+    apr_bucket_brigade *bb = baton;
+    apr_status_t rv;
+    
+    rv = apr_brigade_write(bb, NULL, NULL, buffer, len);
+    return (rv == APR_SUCCESS)? 0 : -1;
+}
+
+apr_status_t md_json_writeb(md_json_t *json, md_json_fmt_t fmt, apr_bucket_brigade *bb)
+{
+    size_t flags = (fmt == MD_JSON_FMT_COMPACT)? JSON_COMPACT : JSON_INDENT(2); 
+    int rv = json_dump_callback(json->j, dump_cb, bb, flags);
+    return rv? APR_EGENERAL : APR_SUCCESS;
+}
+
+static int chunk_cb(const char *buffer, size_t len, void *baton)
+{
+    apr_array_header_t *chunks = baton;
+    char *chunk = apr_pcalloc(chunks->pool, len+1);
+    
+    memcpy(chunk, buffer, len);
+    APR_ARRAY_PUSH(chunks, const char *) = chunk;
+    return 0;
+}
+
+const char *md_json_writep(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt)
+{
+    size_t flags = (fmt == MD_JSON_FMT_COMPACT)? JSON_COMPACT : JSON_INDENT(2); 
+    apr_array_header_t *chunks;
+    int rv;
+
+    chunks = apr_array_make(p, 10, sizeof(char *));
+    rv = json_dump_callback(json->j, chunk_cb, chunks, flags);
+
+    if (rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p,
+                      "md_json_writep failed to dump JSON");
+        return NULL;
+    }
+
+    switch (chunks->nelts) {
+        case 0:
+            return "";
+        case 1:
+            return APR_ARRAY_IDX(chunks, 0, const char *);
+        default:
+            return apr_array_pstrcat(p, chunks, 0);
+    }
+}
+
+apr_status_t md_json_writef(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt, apr_file_t *f)
+{
+    apr_status_t rv;
+    const char *s;
+    
+    s = md_json_writep(json, p, fmt);
+
+    if (s) {
+        rv = apr_file_write_full(f, s, strlen(s), NULL);
+    }
+    else {
+        rv = APR_EINVAL;
+    }
+
+    if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, json->p, "md_json_writef");
+    }
+    return rv;
+}
+
+apr_status_t md_json_fcreatex(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt, 
+                              const char *fpath, apr_fileperms_t perms)
+{
+    apr_status_t rv;
+    apr_file_t *f;
+    
+    rv = md_util_fcreatex(&f, fpath, perms, p);
+    if (APR_SUCCESS == rv) {
+        rv = md_json_writef(json, p, fmt, f);
+        apr_file_close(f);
+    }
+    return rv;
+}
+
+static apr_status_t write_json(void *baton, apr_file_t *f, apr_pool_t *p)
+{
+    j_write_ctx *ctx = baton;
+    apr_status_t rv = md_json_writef(ctx->json, p, ctx->fmt, f);
+    if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "freplace json in %s", ctx->fname);
+    }
+    return rv;
+}
+
+apr_status_t md_json_freplace(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt, 
+                              const char *fpath, apr_fileperms_t perms)
+{
+    j_write_ctx ctx;
+    ctx.json = json;
+    ctx.fmt = fmt;
+    ctx.fname = fpath;
+    return md_util_freplace(fpath, perms, p, write_json, &ctx);
+}
+
+apr_status_t md_json_readd(md_json_t **pjson, apr_pool_t *pool, const char *data, size_t data_len)
+{
+    json_error_t error;
+    json_t *j;
+    
+    j = json_loadb(data, data_len, 0, &error);
+    if (!j) {
+        return APR_EINVAL;
+    }
+    *pjson = json_create(pool, j);
+    return APR_SUCCESS;
+}
+
+static size_t load_cb(void *data, size_t max_len, void *baton)
+{
+    apr_bucket_brigade *body = baton;
+    size_t blen, read_len = 0;
+    const char *bdata;
+    char *dest = data;
+    apr_bucket *b;
+    apr_status_t rv;
+    
+    while (body && !APR_BRIGADE_EMPTY(body) && max_len > 0) {
+        b = APR_BRIGADE_FIRST(body);
+        if (APR_BUCKET_IS_METADATA(b)) {
+            if (APR_BUCKET_IS_EOS(b)) {
+                body = NULL;
+            }
+        }
+        else {
+            rv = apr_bucket_read(b, &bdata, &blen, APR_BLOCK_READ);
+            if (rv == APR_SUCCESS) {
+                if (blen > max_len) {
+                    apr_bucket_split(b, max_len);
+                    blen = max_len;
+                }
+                memcpy(dest, bdata, blen);
+                read_len += blen;
+                max_len -= blen;
+                dest += blen;
+            }
+            else {
+                body = NULL;
+                if (!APR_STATUS_IS_EOF(rv)) {
+                    /* everything beside EOF is an error */
+                    read_len = (size_t)-1;
+                }
+            }
+        }
+        APR_BUCKET_REMOVE(b);
+        apr_bucket_delete(b);
+    }
+    
+    return read_len;
+}
+
+apr_status_t md_json_readb(md_json_t **pjson, apr_pool_t *pool, apr_bucket_brigade *bb)
+{
+    json_error_t error;
+    json_t *j;
+    
+    j = json_load_callback(load_cb, bb, 0, &error);
+    if (!j) {
+        return APR_EINVAL;
+    }
+    *pjson = json_create(pool, j);
+    return APR_SUCCESS;
+}
+
+static size_t load_file_cb(void *data, size_t max_len, void *baton)
+{
+    apr_file_t *f = baton;
+    apr_size_t len = max_len;
+    apr_status_t rv;
+    
+    rv = apr_file_read(f, data, &len);
+    if (APR_SUCCESS == rv) {
+        return len;
+    }
+    else if (APR_EOF == rv) {
+        return 0;
+    }
+    return (size_t)-1;
+}
+
+apr_status_t md_json_readf(md_json_t **pjson, apr_pool_t *p, const char *fpath)
+{
+    apr_file_t *f;
+    json_t *j;
+    apr_status_t rv;
+    json_error_t error;
+    
+    rv = apr_file_open(&f, fpath, APR_FOPEN_READ, 0, p);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+
+    j = json_load_callback(load_file_cb, f, 0, &error);
+    if (j) {
+        *pjson = json_create(p, j);
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p,
+                      "failed to load JSON file %s: %s (line %d:%d)",
+                      fpath, error.text, error.line, error.column);
+    }
+
+    apr_file_close(f);
+    return (j && *pjson) ? APR_SUCCESS : APR_EINVAL;
+}
+
+/**************************************************************************************************/
+/* http get */
+
+apr_status_t md_json_read_http(md_json_t **pjson, apr_pool_t *pool, const md_http_response_t *res)
+{
+    apr_status_t rv = APR_ENOENT;
+    if (res->rv == APR_SUCCESS) {
+        const char *ctype = apr_table_get(res->headers, "content-type");
+        if (ctype && res->body && (strstr(ctype, "/json") || strstr(ctype, "+json"))) {
+            rv = md_json_readb(pjson, pool, res->body);
+        }
+    }
+    return rv;
+}
+
+typedef struct {
+    apr_status_t rv;
+    apr_pool_t *pool;
+    md_json_t *json;
+} resp_data;
+
+static apr_status_t json_resp_cb(const md_http_response_t *res)
+{
+    resp_data *resp = res->req->baton;
+    return md_json_read_http(&resp->json, resp->pool, res);
+}
+
+apr_status_t md_json_http_get(md_json_t **pjson, apr_pool_t *pool,
+                              struct md_http_t *http, const char *url)
+{
+    long req_id;
+    apr_status_t rv;
+    resp_data resp;
+    
+    memset(&resp, 0, sizeof(resp));
+    resp.pool = pool;
+    
+    rv = md_http_GET(http, url, NULL, json_resp_cb, &resp, &req_id);
+    
+    if (rv == APR_SUCCESS) {
+        md_http_await(http, req_id);
+        *pjson = resp.json;
+        return resp.rv;
+    }
+    *pjson = NULL;
+    return rv;
+}
+
diff --git a/modules/md/md_json.h b/modules/md/md_json.h
new file mode 100644
index 0000000000..dde3d240e3
--- /dev/null
+++ b/modules/md/md_json.h
@@ -0,0 +1,121 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_json_h
+#define mod_md_md_json_h
+
+#include <apr_file_io.h>
+
+struct apr_bucket_brigade;
+struct apr_file_t;
+
+struct md_http_t;
+struct md_http_response_t;
+
+
+typedef struct md_json_t md_json_t;
+
+typedef enum {
+    MD_JSON_FMT_COMPACT,
+    MD_JSON_FMT_INDENT,
+} md_json_fmt_t;
+
+md_json_t *md_json_create(apr_pool_t *pool);
+void md_json_destroy(md_json_t *json);
+
+md_json_t *md_json_copy(apr_pool_t *pool, md_json_t *json);
+md_json_t *md_json_clone(apr_pool_t *pool, md_json_t *json);
+
+int md_json_has_key(md_json_t *json, ...);
+
+/* boolean manipulation */
+int md_json_getb(md_json_t *json, ...);
+apr_status_t md_json_setb(int value, md_json_t *json, ...);
+
+/* number manipulation */
+double md_json_getn(md_json_t *json, ...);
+apr_status_t md_json_setn(double value, md_json_t *json, ...);
+
+/* long manipulation */
+long md_json_getl(md_json_t *json, ...);
+apr_status_t md_json_setl(long value, md_json_t *json, ...);
+
+/* string manipulation */
+md_json_t *md_json_create_s(apr_pool_t *pool, const char *s);
+const char *md_json_gets(md_json_t *json, ...);
+const char *md_json_dups(apr_pool_t *p, md_json_t *json, ...);
+apr_status_t md_json_sets(const char *s, md_json_t *json, ...);
+
+/* json manipulation */
+md_json_t *md_json_getj(md_json_t *json, ...);
+apr_status_t md_json_setj(md_json_t *value, md_json_t *json, ...);
+apr_status_t md_json_addj(md_json_t *value, md_json_t *json, ...);
+
+/* Array/Object manipulation */
+apr_status_t md_json_clr(md_json_t *json, ...);
+apr_status_t md_json_del(md_json_t *json, ...);
+
+/* conversion function from and to json */
+typedef apr_status_t md_json_to_cb(void *value, md_json_t *json, apr_pool_t *p, void *baton);
+typedef apr_status_t md_json_from_cb(void **pvalue, md_json_t *json, apr_pool_t *p, void *baton);
+
+/* identity pass through from json to json */
+apr_status_t md_json_pass_to(void *value, md_json_t *json, apr_pool_t *p, void *baton);
+apr_status_t md_json_pass_from(void **pvalue, md_json_t *json, apr_pool_t *p, void *baton);
+
+/* conversions from json to json in specified pool */
+apr_status_t md_json_clone_to(void *value, md_json_t *json, apr_pool_t *p, void *baton);
+apr_status_t md_json_clone_from(void **pvalue, md_json_t *json, apr_pool_t *p, void *baton);
+
+/* Manipulating/Iteration on generic Arrays */
+apr_status_t md_json_geta(apr_array_header_t *a, md_json_from_cb *cb, 
+                          void *baton, md_json_t *json, ...);
+apr_status_t md_json_seta(apr_array_header_t *a, md_json_to_cb *cb, 
+                          void *baton, md_json_t *json, ...);
+
+typedef int md_json_itera_cb(void *baton, size_t index, md_json_t *json);
+int md_json_itera(md_json_itera_cb *cb, void *baton, md_json_t *json, ...);
+
+/* Manipulating Object String values */
+apr_status_t md_json_gets_dict(apr_table_t *dict, md_json_t *json, ...);
+apr_status_t md_json_sets_dict(apr_table_t *dict, md_json_t *json, ...);
+
+/* Manipulating String Arrays */
+apr_status_t md_json_getsa(apr_array_header_t *a, md_json_t *json, ...);
+apr_status_t md_json_dupsa(apr_array_header_t *a, apr_pool_t *p, md_json_t *json, ...);
+apr_status_t md_json_setsa(apr_array_header_t *a, md_json_t *json, ...);
+
+/* serialization & parsing */
+apr_status_t md_json_writeb(md_json_t *json, md_json_fmt_t fmt, struct apr_bucket_brigade *bb);
+const char *md_json_writep(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt);
+apr_status_t md_json_writef(md_json_t *json, apr_pool_t *p, 
+                            md_json_fmt_t fmt, struct apr_file_t *f);
+apr_status_t md_json_fcreatex(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt, 
+                              const char *fpath, apr_fileperms_t perms);
+apr_status_t md_json_freplace(md_json_t *json, apr_pool_t *p, md_json_fmt_t fmt, 
+                              const char *fpath, apr_fileperms_t perms);
+
+apr_status_t md_json_readb(md_json_t **pjson, apr_pool_t *pool, struct apr_bucket_brigade *bb);
+apr_status_t md_json_readd(md_json_t **pjson, apr_pool_t *pool, const char *data, size_t data_len);
+apr_status_t md_json_readf(md_json_t **pjson, apr_pool_t *pool, const char *fpath);
+
+
+/* http retrieval */
+apr_status_t md_json_http_get(md_json_t **pjson, apr_pool_t *pool,
+                              struct md_http_t *http, const char *url);
+apr_status_t md_json_read_http(md_json_t **pjson, apr_pool_t *pool, 
+                               const struct md_http_response_t *res);
+
+#endif /* md_json_h */
diff --git a/modules/md/md_jws.c b/modules/md/md_jws.c
new file mode 100644
index 0000000000..f3788b3f88
--- /dev/null
+++ b/modules/md/md_jws.c
@@ -0,0 +1,105 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_tables.h>
+#include <apr_buckets.h>
+
+#include "md_crypt.h"
+#include "md_json.h"
+#include "md_jws.h"
+#include "md_log.h"
+#include "md_util.h"
+
+static int header_set(void *data, const char *key, const char *val)
+{
+    md_json_sets(val, (md_json_t *)data, key, NULL);
+    return 1;
+}
+
+apr_status_t md_jws_sign(md_json_t **pmsg, apr_pool_t *p,
+                         const char *payload, size_t len, 
+                         struct apr_table_t *protected, 
+                         struct md_pkey_t *pkey, const char *key_id)
+{
+    md_json_t *msg, *jprotected;
+    const char *prot64, *pay64, *sign64, *sign, *prot;
+    apr_status_t rv = APR_SUCCESS;
+
+    *pmsg = NULL;
+    
+    msg = md_json_create(p);
+
+    jprotected = md_json_create(p);
+    md_json_sets("RS256", jprotected, "alg", NULL);
+    if (key_id) {
+        md_json_sets(key_id, jprotected, "kid", NULL);
+    }
+    else {
+        md_json_sets(md_pkey_get_rsa_e64(pkey, p), jprotected, "jwk", "e", NULL);
+        md_json_sets("RSA", jprotected, "jwk", "kty", NULL);
+        md_json_sets(md_pkey_get_rsa_n64(pkey, p), jprotected, "jwk", "n", NULL);
+    }
+    apr_table_do(header_set, jprotected, protected, NULL);
+    prot = md_json_writep(jprotected, p, MD_JSON_FMT_COMPACT);
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE4, 0, p, "protected: %s",
+                  prot ? prot : "<failed to serialize!>");
+
+    if (!prot) {
+        rv = APR_EINVAL;
+    }
+    
+    if (rv == APR_SUCCESS) {
+        prot64 = md_util_base64url_encode(prot, strlen(prot), p);
+        md_json_sets(prot64, msg, "protected", NULL);
+        pay64 = md_util_base64url_encode(payload, len, p);
+
+        md_json_sets(pay64, msg, "payload", NULL);
+        sign = apr_psprintf(p, "%s.%s", prot64, pay64);
+
+        rv = md_crypt_sign64(&sign64, pkey, p, sign, strlen(sign));
+    }
+
+    if (rv == APR_SUCCESS) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, p, 
+                      "jws pay64=%s\nprot64=%s\nsign64=%s", pay64, prot64, sign64);
+        
+        md_json_sets(sign64, msg, "signature", NULL);
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, "jwk signed message");
+    } 
+    
+    *pmsg = (APR_SUCCESS == rv)? msg : NULL;
+    return rv;
+}
+
+apr_status_t md_jws_pkey_thumb(const char **pthumb, apr_pool_t *p, struct md_pkey_t *pkey)
+{
+    const char *e64, *n64, *s;
+    apr_status_t rv;
+    
+    e64 = md_pkey_get_rsa_e64(pkey, p);
+    n64 = md_pkey_get_rsa_n64(pkey, p);
+    if (!e64 || !n64) {
+        return APR_EINVAL;
+    }
+
+    /* whitespace and order is relevant, since we hand out a digest of this */
+    s = apr_psprintf(p, "{\"e\":\"%s\",\"kty\":\"RSA\",\"n\":\"%s\"}", e64, n64);
+    rv = md_crypt_sha256_digest64(pthumb, p, s, strlen(s));
+    return rv;
+}
diff --git a/modules/md/md_jws.h b/modules/md/md_jws.h
new file mode 100644
index 0000000000..bd3a006893
--- /dev/null
+++ b/modules/md/md_jws.h
@@ -0,0 +1,29 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_jws_h
+#define mod_md_md_jws_h
+
+struct apr_table_t;
+struct md_json_t;
+struct md_pkey_t;
+
+apr_status_t md_jws_sign(md_json_t **pmsg, apr_pool_t *p,
+                         const char *payload, size_t len, struct apr_table_t *protected, 
+                         struct md_pkey_t *pkey, const char *key_id);
+
+apr_status_t md_jws_pkey_thumb(const char **pthumb, apr_pool_t *p, struct md_pkey_t *pkey);
+
+#endif /* md_jws_h */
diff --git a/modules/md/md_log.c b/modules/md/md_log.c
new file mode 100644
index 0000000000..de2bcbdca5
--- /dev/null
+++ b/modules/md/md_log.c
@@ -0,0 +1,80 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_buckets.h>
+
+#include "md_log.h"
+
+#define LOG_BUFFER_LEN  1024
+
+static const char *level_names[] = {
+    "emergency",
+    "alert",
+    "crit",
+    "err",
+    "warning",
+    "notice",
+    "info",
+    "debug",
+    "trace1",
+    "trace2",
+    "trace3",
+    "trace4",
+    "trace5",
+    "trace6",
+    "trace7",
+    "trace8",
+};
+
+const char *md_log_level_name(md_log_level_t level)
+{
+    if ((int)level < (sizeof(level_names)/sizeof(level_names[0]))) {
+        return level_names[level];
+    }
+    return "???";
+}
+
+static md_log_print_cb *log_printv;
+static md_log_level_cb *log_level;
+static void *log_baton;
+
+void md_log_set(md_log_level_cb *level_cb, md_log_print_cb *print_cb, void *baton)
+{
+    log_printv = print_cb;
+    log_level = level_cb;
+    log_baton = baton;
+}
+
+int md_log_is_level(apr_pool_t *p, md_log_level_t level)
+{
+    if (!log_level) {
+        return 0;
+    }
+    return log_level(log_baton, p, level);
+}
+
+void md_log_perror(const char *file, int line, md_log_level_t level, 
+                   apr_status_t rv, apr_pool_t *p, const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start(ap, fmt);
+    if (log_printv) {
+        log_printv(file, line, level, rv, log_baton, p, fmt, ap);
+    }
+    va_end(ap);
+}
diff --git a/modules/md/md_log.h b/modules/md/md_log.h
new file mode 100644
index 0000000000..9af15a723c
--- /dev/null
+++ b/modules/md/md_log.h
@@ -0,0 +1,55 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_log_h
+#define mod_md_md_log_h
+
+typedef enum {
+    MD_LOG_EMERG,
+    MD_LOG_ALERT,
+    MD_LOG_CRIT,
+    MD_LOG_ERR, 
+    MD_LOG_WARNING, 
+    MD_LOG_NOTICE, 
+    MD_LOG_INFO, 
+    MD_LOG_DEBUG, 
+    MD_LOG_TRACE1, 
+    MD_LOG_TRACE2, 
+    MD_LOG_TRACE3, 
+    MD_LOG_TRACE4, 
+    MD_LOG_TRACE5, 
+    MD_LOG_TRACE6, 
+    MD_LOG_TRACE7, 
+    MD_LOG_TRACE8, 
+} md_log_level_t;
+
+#define MD_LOG_MARK     __FILE__,__LINE__
+
+const char *md_log_level_name(md_log_level_t level);
+
+int md_log_is_level(apr_pool_t *p, md_log_level_t level);
+
+void md_log_perror(const char *file, int line, md_log_level_t level, 
+                   apr_status_t rv, apr_pool_t *p, const char *fmt, ...);
+
+
+typedef int md_log_level_cb(void *baton, apr_pool_t *p, md_log_level_t level);
+
+typedef void md_log_print_cb(const char *file, int line, md_log_level_t level, 
+                apr_status_t rv, void *baton, apr_pool_t *p, const char *fmt, va_list ap);
+
+void md_log_set(md_log_level_cb *level_cb, md_log_print_cb *print_cb, void *baton);
+
+#endif /* md_log_h */
diff --git a/modules/md/md_os.c b/modules/md/md_os.c
new file mode 100644
index 0000000000..3379acbc2a
--- /dev/null
+++ b/modules/md/md_os.c
@@ -0,0 +1,82 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <apr_strings.h>
+
+#include <mpm_common.h>
+#include <httpd.h>
+#include <http_log.h>
+#include <ap_mpm.h>
+
+#if APR_HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef WIN32
+#include "mpm_winnt.h"
+#endif
+#if AP_NEED_SET_MUTEX_PERMS
+#include "unixd.h"
+#endif
+
+#include "md_util.h"
+#include "md_os.h"
+
+apr_status_t md_try_chown(const char *fname, int uid, int gid, apr_pool_t *p)
+{
+#if AP_NEED_SET_MUTEX_PERMS
+    if (-1 == chown(fname, (uid_t)uid, (gid_t)gid)) {
+        apr_status_t rv = APR_FROM_OS_ERROR(errno);
+        if (!APR_STATUS_IS_ENOENT(rv)) {
+            ap_log_perror(APLOG_MARK, APLOG_ERR, rv, p, APLOGNO()
+                         "Can't change owner of %s", fname);
+        }
+        return rv;
+    }
+    return APR_SUCCESS;
+#else 
+    return APR_ENOTIMPL;
+#endif
+}
+
+apr_status_t md_make_worker_accessible(const char *fname, apr_pool_t *p)
+{
+#if AP_NEED_SET_MUTEX_PERMS
+    return md_try_chown(fname, ap_unixd_config.user_id, -1, p);
+#else 
+    return APR_ENOTIMPL;
+#endif
+}
+
+#ifdef WIN32
+
+apr_status_t md_server_graceful(apr_pool_t *p, server_rec *s)
+{
+    return APR_ENOTIMPL;
+}
+ 
+#else
+
+apr_status_t md_server_graceful(apr_pool_t *p, server_rec *s)
+{ 
+    apr_status_t rv;
+    
+    rv = (kill(getppid(), AP_SIG_GRACEFUL) < 0)? APR_ENOTIMPL : APR_SUCCESS;
+    ap_log_error(APLOG_MARK, APLOG_TRACE1, errno, NULL, "sent signal to parent");
+    return rv;
+}
+
+#endif
+
diff --git a/modules/md/md_os.h b/modules/md/md_os.h
new file mode 100644
index 0000000000..9f5c2b6e8f
--- /dev/null
+++ b/modules/md/md_os.h
@@ -0,0 +1,36 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_os_h
+#define mod_md_md_os_h
+
+/**
+ * Try chown'ing the file/directory. Give id -1 to not change uid/gid.
+ * Will return APR_ENOTIMPL on platforms not supporting this operation.
+ */
+apr_status_t md_try_chown(const char *fname, int uid, int gid, apr_pool_t *p);
+
+/**
+ * Make a file or directory read/write(/searchable) by httpd workers.
+ */
+apr_status_t md_make_worker_accessible(const char *fname, apr_pool_t *p);
+
+/**
+ * Trigger a graceful restart of the server. Depending on the architecture, may
+ * return APR_ENOTIMPL.
+ */
+apr_status_t md_server_graceful(apr_pool_t *p, server_rec *s);
+
+#endif /* mod_md_md_os_h */
diff --git a/modules/md/md_reg.c b/modules/md/md_reg.c
new file mode 100644
index 0000000000..b2953fb909
--- /dev/null
+++ b/modules/md/md_reg.c
@@ -0,0 +1,963 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_hash.h>
+#include <apr_strings.h>
+#include <apr_uri.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_log.h"
+#include "md_json.h"
+#include "md_reg.h"
+#include "md_store.h"
+#include "md_util.h"
+
+#include "md_acme.h"
+#include "md_acme_acct.h"
+
+struct md_reg_t {
+    struct md_store_t *store;
+    struct apr_hash_t *protos;
+    int was_synched;
+    int can_http;
+    int can_https;
+};
+
+/**************************************************************************************************/
+/* life cycle */
+
+apr_status_t md_reg_init(md_reg_t **preg, apr_pool_t *p, struct md_store_t *store)
+{
+    md_reg_t *reg;
+    apr_status_t rv;
+    
+    reg = apr_pcalloc(p, sizeof(*reg));
+    reg->store = store;
+    reg->protos = apr_hash_make(p);
+    reg->can_http = 1;
+    reg->can_https = 1;
+    
+    rv = md_acme_protos_add(reg->protos, p);
+    
+    *preg = (rv == APR_SUCCESS)? reg : NULL;
+    return rv;
+}
+
+struct md_store_t *md_reg_store_get(md_reg_t *reg)
+{
+    return reg->store;
+}
+
+/**************************************************************************************************/
+/* checks */
+
+static apr_status_t check_values(md_reg_t *reg, apr_pool_t *p, const md_t *md, int fields)
+{
+    apr_status_t rv = APR_SUCCESS;
+    const char *err = NULL;
+    
+    if (MD_UPD_DOMAINS & fields) {
+        const md_t *other;
+        const char *domain;
+        int i;
+        
+        if (!md->domains || md->domains->nelts <= 0) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, APR_EINVAL, p, 
+                          "empty domain list: %s", md->name);
+            return APR_EINVAL;
+        }
+        
+        for (i = 0; i < md->domains->nelts; ++i) {
+            domain = APR_ARRAY_IDX(md->domains, i, const char *);
+            if (!md_util_is_dns_name(p, domain, 1)) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, p, 
+                              "md %s with invalid domain name: %s", md->name, domain);
+                return APR_EINVAL;
+            }
+        }
+
+        if (NULL != (other = md_reg_find_overlap(reg, md, &domain, p))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, p, 
+                          "md %s shares domain '%s' with md %s", 
+                          md->name, domain, other->name);
+            return APR_EINVAL;
+        }
+    }
+    
+    if (MD_UPD_CONTACTS & fields) {
+        const char *contact;
+        int i;
+
+        for (i = 0; i < md->contacts->nelts && !err; ++i) {
+            contact = APR_ARRAY_IDX(md->contacts, i, const char *);
+            rv = md_util_abs_uri_check(p, contact, &err);
+            
+            if (err) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, p, 
+                              "contact for %s invalid (%s): %s", md->name, err, contact);
+                return APR_EINVAL;
+            }
+        }
+    }
+    
+    if ((MD_UPD_CA_URL & fields) && md->ca_url) { /* setting to empty is ok */
+        rv = md_util_abs_uri_check(p, md->ca_url, &err);
+        if (err) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, p, 
+                          "CA url for %s invalid (%s): %s", md->name, err, md->ca_url);
+            return APR_EINVAL;
+        }
+    }
+    
+    if ((MD_UPD_CA_PROTO & fields) && md->ca_proto) { /* setting to empty is ok */
+        /* Do we want to restrict this to "known" protocols? */
+    }
+    
+    if ((MD_UPD_CA_ACCOUNT & fields) && md->ca_account) { /* setting to empty is ok */
+        /* hmm, in case we know the protocol, some checks could be done */
+    }
+
+    if ((MD_UPD_AGREEMENT & fields) && md->ca_agreement) { /* setting to empty is ok */
+        rv = md_util_abs_uri_check(p, md->ca_agreement, &err);
+        if (err) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, p, 
+                          "CA url for %s invalid (%s): %s", md->name, err, md->ca_agreement);
+            return APR_EINVAL;
+        }
+    }
+
+    return rv;
+}
+
+/**************************************************************************************************/
+/* state assessment */
+
+static apr_status_t state_init(md_reg_t *reg, apr_pool_t *p, md_t *md)
+{
+    md_state_t state = MD_S_UNKNOWN;
+    const md_creds_t *creds;
+    const md_cert_t *cert;
+    apr_time_t expires = 0;
+    apr_status_t rv;
+    int i;
+
+    if (APR_SUCCESS == (rv = md_reg_creds_get(&creds, reg, MD_SG_DOMAINS, md, p))) {
+        state = MD_S_INCOMPLETE;
+        if (!creds->pkey) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                          "md{%s}: incomplete, without private key", md->name);
+        }
+        else if (!creds->cert) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                          "md{%s}: incomplete, has key but no certificate", md->name);
+        }
+        else if (!creds->chain) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                          "md{%s}: incomplete, has key and certificate, but no chain file.", 
+                          md->name);
+        }
+        else {
+            expires = md_cert_get_not_after(creds->cert);
+            if (md_cert_has_expired(creds->cert)) {
+                state = MD_S_EXPIRED;
+                md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                              "md{%s}: expired, certificate has expired", md->name);
+                goto out;
+            }
+            if (!md_cert_is_valid_now(creds->cert)) {
+                state = MD_S_ERROR;
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, 
+                              "md{%s}: error, certificate valid in future (clock wrong?)", 
+                              md->name);
+                goto out;
+            }
+            if (!md_cert_covers_md(creds->cert, md)) {
+                state = MD_S_INCOMPLETE;
+                md_log_perror(MD_LOG_MARK, MD_LOG_INFO, rv, p, 
+                              "md{%s}: incomplete, cert no longer covers all domains, "
+                              "needs sign up for a new certificate", md->name);
+                goto out;
+            }
+
+            for (i = 0; i < creds->chain->nelts; ++i) {
+                cert = APR_ARRAY_IDX(creds->chain, i, const md_cert_t *);
+                if (!md_cert_is_valid_now(cert)) {
+                    state = MD_S_ERROR;
+                    md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, 
+                                  "md{%s}: error, the certificate itself is valid, however the %d. "
+                                  "certificate in the chain is not valid now (clock wrong?).", 
+                                  md->name, i);
+                    goto out;
+                }
+            } 
+
+            state = MD_S_COMPLETE;
+            md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "md{%s}: is complete", md->name);
+        }
+    }
+
+out:    
+    if (APR_SUCCESS != rv) {
+        state = MD_S_ERROR;
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, "md{%s}: error", md->name);
+    }
+    md->state = state;
+    md->expires = expires;
+    return rv;
+}
+
+static apr_status_t state_vinit(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_reg_t *reg = baton;
+    md_t *md = va_arg(ap, md_t *);
+    
+    return state_init(reg, p, md);
+}
+
+static apr_status_t md_state_init(md_reg_t *reg, md_t *md, apr_pool_t *p)
+{
+    return md_util_pool_vdo(state_vinit, reg, p, md, NULL);
+}
+
+static md_t *state_check(md_reg_t *reg, md_t *md, apr_pool_t *p) 
+{
+    if (md) {
+        int ostate = md->state;
+        if (APR_SUCCESS == state_init(reg, p, md) && md->state != ostate) {
+            md_save(reg->store, p, MD_SG_DOMAINS, md, 0);
+        }
+    }
+    return md;
+}
+
+apr_status_t md_reg_assess(md_reg_t *reg, md_t *md, int *perrored, int *prenew, apr_pool_t *p)
+{
+    int renew = 0;
+    int errored = 0;
+    apr_time_t now = apr_time_now();
+    
+    switch (md->state) {
+        case MD_S_UNKNOWN:
+            md_log_perror( MD_LOG_MARK, MD_LOG_ERR, 0, p, "md(%s): in unkown state.", md->name);
+            break;
+        case MD_S_ERROR:
+            md_log_perror( MD_LOG_MARK, MD_LOG_ERR, 0, p,  
+                         "md(%s): in error state, unable to drive forward. It could "
+                         "be that files have gotten corrupted. You may check with "
+                         "a2md the status of this managed domain to diagnose the "
+                         " problem. As a last resort, you may delete the files for "
+                         " this md and start all over.", md->name);
+            errored = 1;
+            break;
+        case MD_S_COMPLETE:
+            if (!md->expires) {
+                md_log_perror( MD_LOG_MARK, MD_LOG_WARNING, 0, p,  
+                             "md(%s): looks complete, but has unknown expiration date.", md->name);
+                errored = 1;
+            }
+            else if (md->expires <= now) {
+                /* Maybe we hibernated in the meantime? */
+                md->state = MD_S_EXPIRED;
+                renew = 1;
+            }
+            else if ((md->expires - now) <= md->renew_window) {
+                int days = (int)(apr_time_sec(md->expires - now) / MD_SECS_PER_DAY);
+                md_log_perror( MD_LOG_MARK, MD_LOG_DEBUG, 0, p,  
+                              "md(%s): %d days to expiry, attempt renewal", md->name, days);
+                renew = 1;
+            }
+            break;
+        case MD_S_INCOMPLETE:
+        case MD_S_EXPIRED:
+            renew = 1;
+            break;
+    }
+    *prenew = renew;
+    *perrored = errored;
+    return APR_SUCCESS;
+}
+
+/**************************************************************************************************/
+/* iteration */
+
+typedef struct {
+    md_reg_t *reg;
+    md_reg_do_cb *cb;
+    void *baton;
+    const char *exclude;
+    const void *result;
+} reg_do_ctx;
+
+static int reg_md_iter(void *baton, md_store_t *store, md_t *md, apr_pool_t *ptemp)
+{
+    reg_do_ctx *ctx = baton;
+    
+    if (!ctx->exclude || strcmp(ctx->exclude, md->name)) {
+        md = state_check(ctx->reg, (md_t*)md, ptemp);
+        return ctx->cb(ctx->baton, ctx->reg, md);
+    }
+    return 1;
+}
+
+static int reg_do(md_reg_do_cb *cb, void *baton, md_reg_t *reg, apr_pool_t *p, const char *exclude)
+{
+    reg_do_ctx ctx;
+    
+    ctx.reg = reg;
+    ctx.cb = cb;
+    ctx.baton = baton;
+    ctx.exclude = exclude;
+    return md_store_md_iter(reg_md_iter, &ctx, reg->store, p, MD_SG_DOMAINS, "*");
+}
+
+
+int md_reg_do(md_reg_do_cb *cb, void *baton, md_reg_t *reg, apr_pool_t *p)
+{
+    return reg_do(cb, baton, reg, p, NULL);
+}
+
+/**************************************************************************************************/
+/* lookup */
+
+md_t *md_reg_get(md_reg_t *reg, const char *name, apr_pool_t *p)
+{
+    md_t *md;
+    
+    if (APR_SUCCESS == md_load(reg->store, MD_SG_DOMAINS, name, &md, p)) {
+        return state_check(reg, md, p);
+    }
+    return NULL;
+}
+
+typedef struct {
+    const char *domain;
+    md_t *md;
+} find_domain_ctx;
+
+static int find_domain(void *baton, md_reg_t *reg, md_t *md)
+{
+    find_domain_ctx *ctx = baton;
+    
+    if (md_contains(md, ctx->domain)) {
+        ctx->md = md;
+        return 0;
+    }
+    return 1;
+}
+
+md_t *md_reg_find(md_reg_t *reg, const char *domain, apr_pool_t *p)
+{
+    find_domain_ctx ctx;
+
+    ctx.domain = domain;
+    ctx.md = NULL;
+    
+    md_reg_do(find_domain, &ctx, reg, p);
+    return state_check(reg, (md_t*)ctx.md, p);
+}
+
+typedef struct {
+    const md_t *md_checked;
+    const md_t *md;
+    const char *s;
+} find_overlap_ctx;
+
+static int find_overlap(void *baton, md_reg_t *reg, md_t *md)
+{
+    find_overlap_ctx *ctx = baton;
+    const char *overlap;
+    
+    if ((overlap = md_common_name(ctx->md_checked, md))) {
+        ctx->md = md;
+        ctx->s = overlap;
+        return 0;
+    }
+    return 1;
+}
+
+md_t *md_reg_find_overlap(md_reg_t *reg, const md_t *md, const char **pdomain, apr_pool_t *p)
+{
+    find_overlap_ctx ctx;
+    
+    ctx.md_checked = md;
+    ctx.md = NULL;
+    ctx.s = NULL;
+    
+    reg_do(find_overlap, &ctx, reg, p, md->name);
+    if (pdomain && ctx.s) {
+        *pdomain = ctx.s;
+    }
+    return state_check(reg, (md_t*)ctx.md, p);
+}
+
+apr_status_t md_reg_get_cred_files(md_reg_t *reg, const md_t *md, apr_pool_t *p,
+                                   const char **pkeyfile, const char **pcertfile,
+                                   const char **pchainfile)
+{
+    apr_status_t rv;
+    
+    rv = md_store_get_fname(pkeyfile, reg->store, MD_SG_DOMAINS, md->name, MD_FN_PKEY, p);
+    if (APR_SUCCESS == rv) {
+        rv = md_store_get_fname(pcertfile, reg->store, MD_SG_DOMAINS, md->name, MD_FN_CERT, p);
+    }
+    if (APR_SUCCESS == rv) {
+        rv = md_store_get_fname(pchainfile, reg->store, MD_SG_DOMAINS, md->name, MD_FN_CHAIN, p);
+        if (APR_STATUS_IS_ENOENT(rv)) {
+            *pchainfile = NULL;
+            rv = APR_SUCCESS;
+        }
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* manipulation */
+
+static apr_status_t p_md_add(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_reg_t *reg = baton;
+    apr_status_t rv = APR_SUCCESS;
+    md_t *md, *mine;
+    
+    md = va_arg(ap, md_t *);
+    mine = md_clone(ptemp, md);
+    if (APR_SUCCESS == (rv = check_values(reg, ptemp, md, MD_UPD_ALL))
+        && APR_SUCCESS == (rv = md_state_init(reg, mine, ptemp))
+        && APR_SUCCESS == (rv = md_save(reg->store, p, MD_SG_DOMAINS, mine, 1))) {
+    }
+    return rv;
+}
+
+apr_status_t md_reg_add(md_reg_t *reg, md_t *md, apr_pool_t *p)
+{
+    return md_util_pool_vdo(p_md_add, reg, p, md, NULL);
+}
+
+static apr_status_t p_md_update(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_reg_t *reg = baton;
+    apr_status_t rv = APR_SUCCESS;
+    const char *name;
+    const md_t *md, *updates;
+    int fields;
+    md_t *nmd;
+    
+    name = va_arg(ap, const char *);
+    updates = va_arg(ap, const md_t *);
+    fields = va_arg(ap, int);
+    
+    if (NULL == (md = md_reg_get(reg, name, ptemp))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, APR_ENOENT, ptemp, "md %s", name);
+        return APR_ENOENT;
+    }
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, ptemp, "update md %s", name);
+    
+    if (APR_SUCCESS != (rv = check_values(reg, ptemp, updates, fields))) {
+        return rv;
+    }
+    
+    nmd = md_copy(ptemp, md);
+    if (MD_UPD_DOMAINS & fields) {
+        nmd->domains = updates->domains;
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update domains: %s", name);
+    }
+    if (MD_UPD_CA_URL & fields) {
+        nmd->ca_url = updates->ca_url;
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update ca url: %s", name);
+    }
+    if (MD_UPD_CA_PROTO & fields) {
+        nmd->ca_proto = updates->ca_proto;
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update ca protocol: %s", name);
+    }
+    if (MD_UPD_CA_ACCOUNT & fields) {
+        nmd->ca_account = updates->ca_account;
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update account: %s", name);
+    }
+    if (MD_UPD_CONTACTS & fields) {
+        nmd->contacts = updates->contacts;
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update contacts: %s", name);
+    }
+    if (MD_UPD_AGREEMENT & fields) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update agreement: %s", name);
+        nmd->ca_agreement = updates->ca_agreement;
+    }
+    if (MD_UPD_CERT_URL & fields) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update cert url: %s", name);
+        nmd->cert_url = updates->cert_url;
+    }
+    if (MD_UPD_DRIVE_MODE & fields) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update drive-mode: %s", name);
+        nmd->drive_mode = updates->drive_mode;
+    }
+    if (MD_UPD_RENEW_WINDOW & fields) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update renew-window: %s", name);
+        nmd->renew_window = updates->renew_window;
+    }
+    if (MD_UPD_CA_CHALLENGES & fields) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE1, 0, ptemp, "update ca challenges: %s", name);
+        nmd->ca_challenges = (updates->ca_challenges? 
+                              apr_array_copy(p, updates->ca_challenges) : NULL);
+    }
+    
+    if (fields && APR_SUCCESS == (rv = md_save(reg->store, p, MD_SG_DOMAINS, nmd, 0))) {
+        rv = md_state_init(reg, nmd, ptemp);
+    }
+    return rv;
+}
+
+apr_status_t md_reg_update(md_reg_t *reg, apr_pool_t *p, 
+                           const char *name, const md_t *md, int fields)
+{
+    return md_util_pool_vdo(p_md_update, reg, p, name, md, fields, NULL);
+}
+
+/**************************************************************************************************/
+/* certificate related */
+
+static int ok_or_noent(apr_status_t rv) 
+{
+    return (APR_SUCCESS == rv || APR_ENOENT == rv);
+}
+
+static apr_status_t creds_load(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_reg_t *reg = baton;
+    apr_status_t rv;
+    md_cert_t *cert;
+    md_pkey_t *pkey;
+    apr_array_header_t *chain;
+    md_creds_t *creds, **pcreds;
+    const md_t *md;
+    md_cert_state_t cert_state;
+    md_store_group_t group;
+    
+    pcreds = va_arg(ap, md_creds_t **);
+    group = va_arg(ap, int);
+    md = va_arg(ap, const md_t *);
+    
+    if (ok_or_noent(rv = md_cert_load(reg->store, group, md->name, &cert, p))
+        && ok_or_noent(rv = md_pkey_load(reg->store, group, md->name, &pkey, p))
+        && ok_or_noent(rv = md_chain_load(reg->store, group, md->name, &chain, p))) {
+        rv = APR_SUCCESS;
+            
+        creds = apr_pcalloc(p, sizeof(*creds));
+        creds->cert = cert;
+        creds->pkey = pkey;
+        creds->chain = chain;
+        
+        if (creds->cert) {
+            switch ((cert_state = md_cert_state_get(creds->cert))) {
+                case MD_CERT_VALID:
+                    creds->expired = 0;
+                    break;
+                case MD_CERT_EXPIRED:
+                    creds->expired = 1;
+                    break;
+                default:
+                    md_log_perror(MD_LOG_MARK, MD_LOG_ERR, APR_EINVAL, ptemp, 
+                                  "md %s has unexpected cert state: %d", md->name, cert_state);
+                    rv = APR_ENOTIMPL;
+                    break;
+            }
+        }
+    }
+    *pcreds = (APR_SUCCESS == rv)? creds : NULL;
+    return rv;
+}
+
+apr_status_t md_reg_creds_get(const md_creds_t **pcreds, md_reg_t *reg, 
+                              md_store_group_t group, const md_t *md, apr_pool_t *p)
+{
+    apr_status_t rv = APR_SUCCESS;
+    md_creds_t *creds;
+    
+    rv = md_util_pool_vdo(creds_load, reg, p, &creds, group, md, NULL);
+    *pcreds = (APR_SUCCESS == rv)? creds : NULL;
+    return rv;
+}
+
+/**************************************************************************************************/
+/* synching */
+
+typedef struct {
+    apr_pool_t *p;
+    apr_array_header_t *conf_mds;
+    apr_array_header_t *store_mds;
+} sync_ctx;
+
+static int find_changes(void *baton, md_store_t *store, md_t *md, apr_pool_t *ptemp)
+{
+    sync_ctx *ctx = baton;
+
+    APR_ARRAY_PUSH(ctx->store_mds, const md_t*) = md_clone(ctx->p, md);
+    return 1;
+}
+
+static apr_status_t load_props(md_reg_t *reg, apr_pool_t *p)
+{
+    md_json_t *json;
+    apr_status_t rv;
+    
+    rv = md_store_load(reg->store, MD_SG_NONE, NULL, MD_FN_HTTPD_JSON, 
+                       MD_SV_JSON, (void**)&json, p);
+    if (APR_SUCCESS == rv) {
+        if (md_json_has_key(json, MD_KEY_PROTO, MD_KEY_HTTP, NULL)) {
+            reg->can_http = md_json_getb(json, MD_KEY_PROTO, MD_KEY_HTTP, NULL);
+        }
+        if (md_json_has_key(json, MD_KEY_PROTO, MD_KEY_HTTPS, NULL)) {
+            reg->can_https = md_json_getb(json, MD_KEY_PROTO, MD_KEY_HTTPS, NULL);
+        }
+    }
+    else if (APR_STATUS_IS_ENOENT(rv)) {
+        rv = APR_SUCCESS;
+    }
+    return rv;
+}
+
+static apr_status_t sync_props(md_reg_t *reg, apr_pool_t *p, int can_http, int can_https)
+{
+    md_json_t *json = md_json_create(p);
+    md_json_setb(can_http, json, MD_KEY_PROTO, MD_KEY_HTTP, NULL);
+    md_json_setb(can_https, json, MD_KEY_PROTO, MD_KEY_HTTPS, NULL);
+    
+    return md_store_save(reg->store, p, MD_SG_NONE, NULL, MD_FN_HTTPD_JSON, MD_SV_JSON, json, 0);
+}
+ 
+/**
+ * Procedure:
+ * 1. Collect all defined "managed domains" (MD). It does not matter where a MD is defined. 
+ *    All MDs need to be unique and have no overlaps in their domain names. 
+ *    Fail the config otherwise. Also, if a vhost matches an MD, it
+ *    needs to *only* have ServerAliases from that MD. There can be no more than one
+ *    matching MD for a vhost. But an MD can apply to several vhosts.
+ * 2. Synchronize with the persistent store. Iterate over all configured MDs and 
+ *   a. create them in the store if they do not already exist, neither under the
+ *      name or with a common domain.
+ *   b. compare domain lists from store and config, if
+ *      - store has dns name in other MD than from config, remove dns name from store def,
+ *        issue WARNING.
+ *      - store misses dns name from config, add dns name and update store
+ *   c. compare MD acme url/protocol, update if changed
+ */
+apr_status_t md_reg_sync(md_reg_t *reg, apr_pool_t *p, apr_pool_t *ptemp, 
+                         apr_array_header_t *master_mds, int can_http, int can_https) 
+{
+    sync_ctx ctx;
+    md_store_t *store = reg->store;
+    apr_status_t rv;
+
+    if (APR_SUCCESS != (rv = sync_props(reg, ptemp, can_http, can_https))) {
+        reg->was_synched = 0;
+        return rv;
+    }
+    
+    reg->was_synched = 1;
+    
+    ctx.p = ptemp;
+    ctx.conf_mds = master_mds;
+    ctx.store_mds = apr_array_make(ptemp, 100, sizeof(md_t *));
+    
+    rv = md_store_md_iter(find_changes, &ctx, store, ptemp, MD_SG_DOMAINS, "*");
+    if (APR_STATUS_IS_ENOENT(rv)) {
+        rv = APR_SUCCESS;
+    }
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                  "sync: found %d mds in store", ctx.store_mds->nelts);
+    if (APR_SUCCESS == rv) {
+        int i, added, fields;
+        md_t *md, *config_md, *smd, *omd;
+        const char *common;
+        
+        for (i = 0; i < ctx.conf_mds->nelts; ++i) {
+            md = APR_ARRAY_IDX(ctx.conf_mds, i, md_t *);
+            
+            /* find the store md that is closest match for the configured md */
+            smd = md_find_closest_match(ctx.store_mds, md);
+            if (smd) {
+                fields = 0;
+                /* add any newly configured domains to the store md */
+                added = md_array_str_add_missing(smd->domains, md->domains, 0);
+                if (added) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                                 "%s: %d domains added", smd->name, added);
+                    fields |= MD_UPD_DOMAINS;
+                }
+                
+                /* Look for other store mds which have domains now being part of smd */
+                while (APR_SUCCESS == rv && (omd = md_get_by_dns_overlap(ctx.store_mds, md))) {
+                    /* find the name now duplicate */
+                    common = md_common_name(md, omd);
+                    assert(common);
+                    
+                    /* Is this md still configured or has it been abandoned in the config? */
+                    config_md = md_get_by_name(ctx.conf_mds, omd->name);
+                    if (config_md && md_contains(config_md, common)) {
+                        /* domain used in two configured mds, not allowed */
+                        rv = APR_EINVAL;
+                        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, 
+                                      "domain %s used in md %s and %s", 
+                                      common, md->name, omd->name);
+                    }
+                    else if (config_md) {
+                        /* domain stored in omd, but no longer has the offending domain,
+                           remove it from the store md. */
+                        omd->domains = md_array_str_remove(ptemp, omd->domains, common, 0);
+                        rv = md_reg_update(reg, ptemp, omd->name, omd, MD_UPD_DOMAINS);
+                    }
+                    else {
+                        /* domain in a store md that is no longer configured, warn about it.
+                         * Remove the domain here, so we can progress, but never save it. */
+                        omd->domains = md_array_str_remove(ptemp, omd->domains, common, 0);
+                        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, 
+                                      "domain %s, configured in md %s, is part of the stored md %s."
+                                      " That md however is no longer mentioned in the config. "
+                                      "If you longer want it, remove the md from the store.", 
+                                      common, md->name, omd->name);
+                    }
+                }
+
+                if (MD_SVAL_UPDATE(md, smd, ca_url)) {
+                    smd->ca_url = md->ca_url;
+                    fields |= MD_UPD_CA_URL;
+                }
+                if (MD_SVAL_UPDATE(md, smd, ca_proto)) {
+                    smd->ca_proto = md->ca_proto;
+                    fields |= MD_UPD_CA_PROTO;
+                }
+                if (MD_SVAL_UPDATE(md, smd, ca_agreement)) {
+                    smd->ca_agreement = md->ca_agreement;
+                    fields |= MD_UPD_AGREEMENT;
+                }
+                if (MD_VAL_UPDATE(md, smd, drive_mode)) {
+                    smd->drive_mode = md->drive_mode;
+                    fields |= MD_UPD_DRIVE_MODE;
+                }
+                if (!apr_is_empty_array(md->contacts) 
+                    && !md_array_str_eq(md->contacts, smd->contacts, 0)) {
+                    smd->contacts = md->contacts;
+                    fields |= MD_UPD_CONTACTS;
+                }
+                if (MD_VAL_UPDATE(md, smd, renew_window)) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, 
+                                  "%s: update renew_window, old=%ld, new=%ld", 
+                                  smd->name, (long)smd->renew_window, md->renew_window);
+                    smd->renew_window = md->renew_window;
+                    fields |= MD_UPD_RENEW_WINDOW;
+                }
+                if (md->ca_challenges) {
+                    md->ca_challenges = md_array_str_compact(p, md->ca_challenges, 0);
+                    if (smd->ca_challenges 
+                        && !md_array_str_eq(md->ca_challenges, smd->ca_challenges, 0)) {
+                        smd->ca_challenges = (md->ca_challenges?
+                                              apr_array_copy(ptemp, md->ca_challenges) : NULL);
+                        fields |= MD_UPD_CA_CHALLENGES;
+                    }
+                }
+                
+                if (fields) {
+                    rv = md_reg_update(reg, ptemp, smd->name, smd, fields);
+                    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "md %s updated", smd->name);
+                }
+            }
+            else {
+                /* new managed domain */
+                rv = md_reg_add(reg, md, ptemp);
+                md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, p, "new md %s added", md->name);
+            }
+        }
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "loading mds");
+    }
+    
+    return rv;
+}
+
+
+/**************************************************************************************************/
+/* driving */
+
+static apr_status_t init_proto_driver(md_proto_driver_t *driver, const md_proto_t *proto, 
+                                      md_reg_t *reg, const md_t *md, 
+                                      const char *challenge, int reset, apr_pool_t *p) 
+{
+    apr_status_t rv = APR_SUCCESS;
+
+    /* If this registry instance was not synched before (and obtained server
+     * properties that way), read them from the store.
+     */
+    if (reg->was_synched 
+        || APR_SUCCESS == (rv = load_props(reg, p))) {
+
+        driver->proto = proto;
+        driver->p = p;
+        driver->challenge = challenge;
+        driver->can_http = reg->can_http;
+        driver->can_https = reg->can_https;
+        driver->reg = reg;
+        driver->store = md_reg_store_get(reg);
+        driver->md = md;
+        driver->reset = reset;
+    }
+
+    return rv;
+}
+
+static apr_status_t run_stage(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_reg_t *reg = baton;
+    const md_proto_t *proto;
+    const md_t *md;
+    int reset;
+    md_proto_driver_t *driver;
+    const char *challenge;
+    apr_status_t rv;
+    
+    proto = va_arg(ap, const md_proto_t *);
+    md = va_arg(ap, const md_t *);
+    challenge = va_arg(ap, const char *);
+    reset = va_arg(ap, int); 
+    
+    driver = apr_pcalloc(ptemp, sizeof(*driver));
+    rv = init_proto_driver(driver, proto, reg, md, challenge, reset, ptemp);
+    if (APR_SUCCESS == rv && 
+        APR_SUCCESS == (rv = proto->init(driver))) {
+        
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, ptemp, "%s: run staging", md->name);
+        rv = proto->stage(driver);
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, ptemp, "%s: staging done", md->name);
+    return rv;
+}
+
+apr_status_t md_reg_stage(md_reg_t *reg, const md_t *md, const char *challenge, 
+                          int reset, apr_pool_t *p)
+{
+    const md_proto_t *proto;
+    
+    if (!md->ca_proto) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, p, "md %s has no CA protocol", md->name);
+        ((md_t *)md)->state = MD_S_ERROR;
+        return APR_SUCCESS;
+    }
+    
+    proto = apr_hash_get(reg->protos, md->ca_proto, strlen(md->ca_proto));
+    if (!proto) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, p, 
+                      "md %s has unknown CA protocol: %s", md->name, md->ca_proto);
+        ((md_t *)md)->state = MD_S_ERROR;
+        return APR_EINVAL;
+    }
+    
+    return md_util_pool_vdo(run_stage, reg, p, proto, md, challenge, reset, NULL);
+}
+
+static apr_status_t run_load(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_reg_t *reg = baton;
+    const char *name;
+    const md_proto_t *proto;
+    const md_t *md, *nmd;
+    md_proto_driver_t *driver;
+    apr_status_t rv;
+    
+    name = va_arg(ap, const char *);
+    
+    if (APR_STATUS_IS_ENOENT(rv = md_load(reg->store, MD_SG_STAGING, name, NULL, ptemp))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, rv, ptemp, "%s: nothing staged", name);
+        return APR_ENOENT;
+    }
+    
+    md = md_reg_get(reg, name, p);
+    if (!md) {
+        return APR_ENOENT;
+    }
+    
+    if (!md->ca_proto) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, p, "md %s has no CA protocol", name);
+        ((md_t *)md)->state = MD_S_ERROR;
+        return APR_EINVAL;
+    }
+    
+    proto = apr_hash_get(reg->protos, md->ca_proto, strlen(md->ca_proto));
+    if (!proto) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, 0, p, 
+                      "md %s has unknown CA protocol: %s", md->name, md->ca_proto);
+        ((md_t *)md)->state = MD_S_ERROR;
+        return APR_EINVAL;
+    }
+    
+    driver = apr_pcalloc(ptemp, sizeof(*driver));
+    init_proto_driver(driver, proto, reg, md, NULL, 0, ptemp);
+
+    if (APR_SUCCESS == (rv = proto->init(driver))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, ptemp, "%s: run load", md->name);
+        
+        if (APR_SUCCESS == (rv = proto->preload(driver, MD_SG_TMP))) {
+            /* swap */
+            rv = md_store_move(reg->store, p, MD_SG_TMP, MD_SG_DOMAINS, md->name, 1);
+            if (APR_SUCCESS == rv) {
+                /* load again */
+                nmd = md_reg_get(reg, md->name, p);
+                if (!nmd) {
+                    rv = APR_ENOENT;
+                    md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "loading md after staging");
+                }
+                else if (nmd->state != MD_S_COMPLETE) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_WARNING, rv, p, 
+                                  "md has state %d after load", nmd->state);
+                }
+                
+                md_store_purge(reg->store, p, MD_SG_STAGING, md->name);
+                md_store_purge(reg->store, p, MD_SG_CHALLENGES, md->name);
+            }
+        }
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, ptemp, "%s: load done", md->name);
+    return rv;
+}
+
+apr_status_t md_reg_load(md_reg_t *reg, const char *name, apr_pool_t *p)
+{
+    return md_util_pool_vdo(run_load, reg, p, name, NULL);
+}
+
+apr_status_t md_reg_drive(md_reg_t *reg, md_t *md, const char *challenge,
+                          int reset, int force, apr_pool_t *p)
+{
+    apr_status_t rv;
+    int errored, renew;
+    
+    if (APR_SUCCESS == (rv = md_reg_assess(reg, md, &errored, &renew, p))) {
+        if (errored) {
+            rv = APR_EGENERAL;
+        }
+        else if (renew || force) {
+            if (APR_SUCCESS == (rv = md_reg_stage(reg, md, challenge, reset, p))) {
+                rv = md_reg_load(reg, md->name, p);
+            }
+        }
+    }
+    return rv;
+}
diff --git a/modules/md/md_reg.h b/modules/md/md_reg.h
new file mode 100644
index 0000000000..d3af921903
--- /dev/null
+++ b/modules/md/md_reg.h
@@ -0,0 +1,182 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_reg_h
+#define mod_md_md_reg_h
+
+struct apr_hash_t;
+struct apr_array_header_t;
+struct md_store_t;
+struct md_pkey_t;
+struct md_cert_t;
+
+/**
+ * A registry for managed domains with a md_store_t as persistence.
+ *
+ */
+typedef struct md_reg_t md_reg_t;
+
+/**
+ * Initialize the registry, using the pool and loading any existing information
+ * from the store.
+ */
+apr_status_t md_reg_init(md_reg_t **preg, apr_pool_t *pm, struct md_store_t *store);
+
+struct md_store_t *md_reg_store_get(md_reg_t *reg);
+
+/**
+ * Add a new md to the registry. This will check the name for uniqueness and
+ * that domain names do not overlap with already existing mds.
+ */
+apr_status_t md_reg_add(md_reg_t *reg, md_t *md, apr_pool_t *p);
+
+/**
+ * Find the md, if any, that contains the given domain name. 
+ * NULL if none found.
+ */
+md_t *md_reg_find(md_reg_t *reg, const char *domain, apr_pool_t *p);
+
+/**
+ * Find one md, which domain names overlap with the given md and that has a different
+ * name. There may be more than one existing md that overlaps. It is not defined
+ * which one will be returned. 
+ */
+md_t *md_reg_find_overlap(md_reg_t *reg, const md_t *md, const char **pdomain, apr_pool_t *p);
+
+/**
+ * Get the md with the given unique name. NULL if it does not exist.
+ * Will update the md->state.
+ */
+md_t *md_reg_get(md_reg_t *reg, const char *name, apr_pool_t *p);
+
+/**
+ * Assess the capability and need to driving this managed domain.
+ */
+apr_status_t md_reg_assess(md_reg_t *reg, md_t *md, int *perrored, int *prenew, apr_pool_t *p);
+
+/**
+ * Callback invoked for every md in the registry. If 0 is returned, iteration stops.
+ */
+typedef int md_reg_do_cb(void *baton, md_reg_t *reg, md_t *md);
+
+/**
+ * Invoke callback for all mds in this registry. Order is not guarantueed.
+ * If the callback returns 0, iteration stops. Returns 0 if iteration was
+ * aborted.
+ */
+int md_reg_do(md_reg_do_cb *cb, void *baton, md_reg_t *reg, apr_pool_t *p);
+
+/**
+ * Bitmask for fields that are updated.
+ */
+#define MD_UPD_DOMAINS      0x0001
+#define MD_UPD_CA_URL       0x0002
+#define MD_UPD_CA_PROTO     0x0004
+#define MD_UPD_CA_ACCOUNT   0x0008
+#define MD_UPD_CONTACTS     0x0010
+#define MD_UPD_AGREEMENT    0x0020
+#define MD_UPD_CERT_URL     0x0040
+#define MD_UPD_DRIVE_MODE   0x0080
+#define MD_UPD_RENEW_WINDOW 0x0100
+#define MD_UPD_CA_CHALLENGES 0x0200
+#define MD_UPD_ALL          0x7FFF
+
+/**
+ * Update the given fields for the managed domain. Take the new
+ * values from the given md, all other values remain unchanged.
+ */
+apr_status_t md_reg_update(md_reg_t *reg, apr_pool_t *p, 
+                           const char *name, const md_t *md, int fields);
+
+/**
+ * Get the credentials available for the managed domain md. Returns APR_ENOENT
+ * when none is available. The returned values are immutable. 
+ */
+apr_status_t md_reg_creds_get(const md_creds_t **pcreds, md_reg_t *reg, 
+                              md_store_group_t group, const md_t *md, apr_pool_t *p);
+
+apr_status_t md_reg_get_cred_files(md_reg_t *reg, const md_t *md, apr_pool_t *p,
+                                   const char **pkeyfile, const char **pcertfile,
+                                   const char **pchainfile);
+
+/**
+ * Synchronise the give master mds with the store.
+ */
+apr_status_t md_reg_sync(md_reg_t *reg, apr_pool_t *p, apr_pool_t *ptemp, 
+                         apr_array_header_t *master_mds, int can_http, int can_https);
+
+/**************************************************************************************************/
+/* protocol drivers */
+
+typedef struct md_proto_t md_proto_t;
+
+typedef struct md_proto_driver_t md_proto_driver_t;
+
+struct md_proto_driver_t {
+    const md_proto_t *proto;
+    apr_pool_t *p;
+    const char *challenge;
+    int can_http;
+    int can_https;
+    struct md_store_t *store;
+    md_reg_t *reg;
+    const md_t *md;
+    void *baton;
+    int reset;
+};
+
+typedef apr_status_t md_proto_init_cb(md_proto_driver_t *driver);
+typedef apr_status_t md_proto_stage_cb(md_proto_driver_t *driver);
+typedef apr_status_t md_proto_preload_cb(md_proto_driver_t *driver, md_store_group_t group);
+
+struct md_proto_t {
+    const char *protocol;
+    md_proto_init_cb *init;
+    md_proto_stage_cb *stage;
+    md_proto_preload_cb *preload;
+};
+
+
+/**
+ * Stage a new credentials set for the given managed domain in a separate location
+ * without interfering with any existing credentials.
+ */
+apr_status_t md_reg_stage(md_reg_t *reg, const md_t *md, 
+                          const char *challenge, int reset, apr_pool_t *p);
+
+/**
+ * Load a staged set of new credentials for the managed domain. This will archive
+ * any existing credential data and make the staged set the new live one.
+ * If staging is incomplete or missing, the load will fail and all credentials remain
+ * as they are.
+ */
+apr_status_t md_reg_load(md_reg_t *reg, const char *name, apr_pool_t *p);
+
+/**
+ * Drive the given managed domain toward completeness.
+ * This is a convenience method that combines staging and, on success, loading
+ * of a new managed domain credentials set.
+ *
+ * @param reg   the md registry
+ * @param md    the managed domain to drive
+ * @param challenge the challenge type to use or NULL for auto selection
+ * @param reset remove any staging information that has been collected
+ * @param force force driving even though it looks unnecessary (e.g. not epxired)
+ * @param p     pool to use
+ */
+apr_status_t md_reg_drive(md_reg_t *reg, md_t *md, 
+                          const char *challenge, int reset, int force, apr_pool_t *p);
+
+#endif /* mod_md_md_reg_h */
diff --git a/modules/md/md_store.c b/modules/md/md_store.c
new file mode 100644
index 0000000000..9028845c6f
--- /dev/null
+++ b/modules/md/md_store.c
@@ -0,0 +1,291 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_file_info.h>
+#include <apr_file_io.h>
+#include <apr_fnmatch.h>
+#include <apr_hash.h>
+#include <apr_strings.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_log.h"
+#include "md_json.h"
+#include "md_store.h"
+#include "md_util.h"
+
+/**************************************************************************************************/
+/* generic callback handling */
+
+#define ASPECT_MD           "md.json"
+#define ASPECT_CERT         "cert.pem"
+#define ASPECT_PKEY         "key.pem"
+#define ASPECT_CHAIN        "chain.pem"
+
+#define GNAME_ACCOUNTS     
+#define GNAME_CHALLENGES   
+#define GNAME_DOMAINS      
+#define GNAME_STAGING      
+#define GNAME_ARCHIVE      
+
+static const char *GROUP_NAME[] = {
+    "none",
+    "accounts",
+    "challenges",
+    "domains",
+    "staging",
+    "archive",
+    "tmp",
+    NULL
+};
+
+const char *md_store_group_name(int group)
+{
+    if (group < sizeof(GROUP_NAME)/sizeof(GROUP_NAME[0])) {
+        return GROUP_NAME[group];
+    }
+    return "UNKNOWN";
+}
+
+void md_store_destroy(md_store_t *store)
+{
+    if (store->destroy) store->destroy(store);
+}
+
+apr_status_t md_store_load(md_store_t *store, md_store_group_t group, 
+                           const char *name, const char *aspect, 
+                           md_store_vtype_t vtype, void **pdata, 
+                           apr_pool_t *p)
+{
+    return store->load(store, group, name, aspect, vtype, pdata, p);
+}
+
+apr_status_t md_store_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                           const char *name, const char *aspect, 
+                           md_store_vtype_t vtype, void *data, 
+                           int create)
+{
+    return store->save(store, p, group, name, aspect, vtype, data, create);
+}
+
+apr_status_t md_store_remove(md_store_t *store, md_store_group_t group, 
+                             const char *name, const char *aspect, 
+                             apr_pool_t *p, int force)
+{
+    return store->remove(store, group, name, aspect, p, force);
+}
+
+apr_status_t md_store_purge(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                             const char *name)
+{
+    return store->purge(store, p, group, name);
+}
+
+apr_status_t md_store_iter(md_store_inspect *inspect, void *baton, md_store_t *store, 
+                           apr_pool_t *p, md_store_group_t group, const char *pattern, 
+                           const char *aspect, md_store_vtype_t vtype)
+{
+    return store->iterate(inspect, baton, store, p, group, pattern, aspect, vtype);
+}
+
+apr_status_t md_store_load_json(md_store_t *store, md_store_group_t group, 
+                                const char *name, const char *aspect, 
+                                struct md_json_t **pdata, apr_pool_t *p)
+{
+    return md_store_load(store, group, name, aspect, MD_SV_JSON, (void**)pdata, p);
+}
+
+apr_status_t md_store_save_json(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                                const char *name, const char *aspect, 
+                                struct md_json_t *data, int create)
+{
+    return md_store_save(store, p, group, name, aspect, MD_SV_JSON, (void*)data, create);
+}
+
+apr_status_t md_store_move(md_store_t *store, apr_pool_t *p, 
+                           md_store_group_t from, md_store_group_t to,
+                           const char *name, int archive)
+{
+    return store->move(store, p, from, to, name, archive);
+}
+
+apr_status_t md_store_get_fname(const char **pfname, 
+                                md_store_t *store, md_store_group_t group, 
+                                const char *name, const char *aspect, 
+                                apr_pool_t *p)
+{
+    if (store->get_fname) {
+        return store->get_fname(pfname, store, group, name, aspect, p);
+    }
+    return APR_ENOTIMPL;
+}
+
+/**************************************************************************************************/
+/* convenience */
+
+typedef struct {
+    md_store_t *store;
+    md_store_group_t group;
+} md_group_ctx;
+
+apr_status_t md_load(md_store_t *store, md_store_group_t group, 
+                     const char *name, md_t **pmd, apr_pool_t *p)
+{
+    md_json_t *json;
+    apr_status_t rv;
+    
+    rv = md_store_load_json(store, group, name, MD_FN_MD, pmd? &json : NULL, p);
+    if (APR_SUCCESS == rv) {
+        if (pmd) {
+            *pmd = md_from_json(json, p);
+        }
+        return APR_SUCCESS;
+    }
+    return rv;
+}
+
+static apr_status_t p_save(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_group_ctx *ctx = baton;
+    md_json_t *json;
+    md_t *md;
+    int create;
+    
+    md = va_arg(ap, md_t *);
+    create = va_arg(ap, int);
+
+    json = md_to_json(md, ptemp);
+    assert(json);
+    assert(md->name);
+    return md_store_save_json(ctx->store, p, ctx->group, md->name, MD_FN_MD, json, create);
+}
+
+apr_status_t md_save(md_store_t *store, apr_pool_t *p, 
+                     md_store_group_t group, md_t *md, int create)
+{
+    md_group_ctx ctx;
+    
+    ctx.store = store;
+    ctx.group = group;
+    return md_util_pool_vdo(p_save, &ctx, p, md, create, NULL);
+}
+
+static apr_status_t p_remove(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_group_ctx *ctx = baton;
+    const char *name;
+    int force;
+    
+    name = va_arg(ap, const char *);
+    force = va_arg(ap, int);
+
+    assert(name);
+    return md_store_remove(ctx->store, ctx->group, name, MD_FN_MD, ptemp, force);
+}
+
+apr_status_t md_remove(md_store_t *store, apr_pool_t *p, 
+                       md_store_group_t group, const char *name, int force)
+{
+    md_group_ctx ctx;
+    
+    ctx.store = store;
+    ctx.group = group;
+    return md_util_pool_vdo(p_remove, &ctx, p, name, force, NULL);
+}
+
+typedef struct {
+    apr_pool_t *p;
+    apr_array_header_t *mds;
+} md_load_ctx;
+
+apr_status_t md_pkey_load(md_store_t *store, md_store_group_t group, const char *name, 
+                          md_pkey_t **ppkey, apr_pool_t *p)
+{
+    return md_store_load(store, group, name, MD_FN_PKEY, MD_SV_PKEY, (void**)ppkey, p);
+}
+
+apr_status_t md_pkey_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, const char *name, 
+                          struct md_pkey_t *pkey, int create)
+{
+    return md_store_save(store, p, group, name, MD_FN_PKEY, MD_SV_PKEY, pkey, create);
+}
+
+apr_status_t md_cert_load(md_store_t *store, md_store_group_t group, const char *name, 
+                          struct md_cert_t **pcert, apr_pool_t *p)
+{
+    return md_store_load(store, group, name, MD_FN_CERT, MD_SV_CERT, (void**)pcert, p);
+}
+
+apr_status_t md_cert_save(md_store_t *store, apr_pool_t *p, 
+                          md_store_group_t group, const char *name, 
+                          struct md_cert_t *cert, int create)
+{
+    return md_store_save(store, p, group, name, MD_FN_CERT, MD_SV_CERT, cert, create);
+}
+
+apr_status_t md_chain_load(md_store_t *store, md_store_group_t group, const char *name, 
+                           struct apr_array_header_t **pchain, apr_pool_t *p)
+{
+    return md_store_load(store, group, name, MD_FN_CHAIN, MD_SV_CHAIN, (void**)pchain, p);
+}
+
+apr_status_t md_chain_save(md_store_t *store, apr_pool_t *p, 
+                           md_store_group_t group, const char *name, 
+                           struct apr_array_header_t *chain, int create)
+{
+    return md_store_save(store, p, group, name, MD_FN_CHAIN, MD_SV_CHAIN, chain, create);
+}
+
+typedef struct {
+    md_store_t *store;
+    md_store_group_t group;
+    const char *pattern;
+    const char *aspect;
+    md_store_md_inspect *inspect;
+    void *baton;
+} inspect_md_ctx;
+
+static int insp_md(void *baton, const char *name, const char *aspect, 
+                   md_store_vtype_t vtype, void *value, apr_pool_t *ptemp)
+{
+    inspect_md_ctx *ctx = baton;
+    
+    if (!strcmp(MD_FN_MD, aspect) && vtype == MD_SV_JSON) {
+        md_t *md = md_from_json(value, ptemp);
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, ptemp, "inspecting md at: %s", name);
+        return ctx->inspect(ctx->baton, ctx->store, md, ptemp);
+    }
+    return 1;
+}
+
+apr_status_t md_store_md_iter(md_store_md_inspect *inspect, void *baton, md_store_t *store, 
+                              apr_pool_t *p, md_store_group_t group, const char *pattern)
+{
+    inspect_md_ctx ctx;
+    
+    ctx.store = store;
+    ctx.group = group;
+    ctx.inspect = inspect;
+    ctx.baton = baton;
+    
+    return md_store_iter(insp_md, &ctx, store, p, group, pattern, MD_FN_MD, MD_SV_JSON);
+}
+
diff --git a/modules/md/md_store.h b/modules/md/md_store.h
new file mode 100644
index 0000000000..7806504bee
--- /dev/null
+++ b/modules/md/md_store.h
@@ -0,0 +1,139 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_store_h
+#define mod_md_md_store_h
+
+struct apr_array_header_t;
+struct md_cert_t;
+struct md_pkey_t;
+
+typedef struct md_store_t md_store_t;
+
+typedef void md_store_destroy_cb(md_store_t *store);
+
+const char *md_store_group_name(int group);
+
+
+typedef apr_status_t md_store_load_cb(md_store_t *store, md_store_group_t group, 
+                                      const char *name, const char *aspect, 
+                                      md_store_vtype_t vtype, void **pvalue, 
+                                      apr_pool_t *p);
+typedef apr_status_t md_store_save_cb(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                                      const char *name, const char *aspect, 
+                                      md_store_vtype_t vtype, void *value, 
+                                      int create);
+typedef apr_status_t md_store_remove_cb(md_store_t *store, md_store_group_t group, 
+                                        const char *name, const char *aspect,  
+                                        apr_pool_t *p, int force);
+typedef apr_status_t md_store_purge_cb(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                                        const char *name);
+
+typedef int md_store_inspect(void *baton, const char *name, const char *aspect, 
+                             md_store_vtype_t vtype, void *value, apr_pool_t *ptemp);
+
+typedef apr_status_t md_store_iter_cb(md_store_inspect *inspect, void *baton, md_store_t *store, 
+                                      apr_pool_t *p, md_store_group_t group, const char *pattern,
+                                      const char *aspect, md_store_vtype_t vtype);
+
+typedef apr_status_t md_store_move_cb(md_store_t *store, apr_pool_t *p, md_store_group_t from, 
+                                      md_store_group_t to, const char *name, int archive);
+
+typedef apr_status_t md_store_get_fname_cb(const char **pfname, 
+                                           md_store_t *store, md_store_group_t group, 
+                                           const char *name, const char *aspect, 
+                                           apr_pool_t *p);
+
+struct md_store_t {
+    md_store_destroy_cb *destroy;
+
+    md_store_save_cb *save;
+    md_store_load_cb *load;
+    md_store_remove_cb *remove;
+    md_store_move_cb *move;
+    md_store_iter_cb *iterate;
+    md_store_purge_cb *purge;
+    md_store_get_fname_cb *get_fname;
+};
+
+void md_store_destroy(md_store_t *store);
+
+apr_status_t md_store_load_json(md_store_t *store, md_store_group_t group, 
+                                const char *name, const char *aspect, 
+                                struct md_json_t **pdata, apr_pool_t *p);
+apr_status_t md_store_save_json(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                                const char *name, const char *aspect, 
+                                struct md_json_t *data, int create);
+
+
+apr_status_t md_store_load(md_store_t *store, md_store_group_t group, 
+                           const char *name, const char *aspect, 
+                           md_store_vtype_t vtype, void **pdata, 
+                           apr_pool_t *p);
+apr_status_t md_store_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                           const char *name, const char *aspect, 
+                           md_store_vtype_t vtype, void *data, 
+                           int create);
+apr_status_t md_store_remove(md_store_t *store, md_store_group_t group, 
+                             const char *name, const char *aspect, 
+                             apr_pool_t *p, int force);
+apr_status_t md_store_purge(md_store_t *store, apr_pool_t *p, 
+                            md_store_group_t group, const char *name);
+
+
+apr_status_t md_store_iter(md_store_inspect *inspect, void *baton, md_store_t *store, 
+                           apr_pool_t *p, md_store_group_t group, const char *pattern, 
+                           const char *aspect, md_store_vtype_t vtype);
+
+apr_status_t md_store_move(md_store_t *store, apr_pool_t *p,
+                           md_store_group_t from, md_store_group_t to,
+                           const char *name, int archive);
+
+apr_status_t md_store_get_fname(const char **pfname, 
+                                md_store_t *store, md_store_group_t group, 
+                                const char *name, const char *aspect, 
+                                apr_pool_t *p);
+
+/**************************************************************************************************/
+/* Storage handling utils */
+
+apr_status_t md_load(md_store_t *store, md_store_group_t group, 
+                     const char *name, md_t **pmd, apr_pool_t *p);
+apr_status_t md_save(struct md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                     md_t *md, int create);
+apr_status_t md_remove(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                     const char *name, int force);
+
+typedef int md_store_md_inspect(void *baton, md_store_t *store, md_t *md, apr_pool_t *ptemp);
+
+apr_status_t md_store_md_iter(md_store_md_inspect *inspect, void *baton, md_store_t *store, 
+                              apr_pool_t *p, md_store_group_t group, const char *pattern);
+
+
+apr_status_t md_pkey_load(md_store_t *store, md_store_group_t group, 
+                          const char *name, struct md_pkey_t **ppkey, apr_pool_t *p);
+apr_status_t md_pkey_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                          const char *name, struct md_pkey_t *pkey, int create);
+apr_status_t md_cert_load(md_store_t *store, md_store_group_t group, 
+                          const char *name, struct md_cert_t **pcert, apr_pool_t *p);
+apr_status_t md_cert_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                          const char *name, struct md_cert_t *cert, int create);
+apr_status_t md_chain_load(md_store_t *store, md_store_group_t group, 
+                           const char *name, struct apr_array_header_t **pchain, apr_pool_t *p);
+apr_status_t md_chain_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                           const char *name, struct apr_array_header_t *chain, int create);
+
+
+#endif /* mod_md_md_store_h */
diff --git a/modules/md/md_store_fs.c b/modules/md/md_store_fs.c
new file mode 100644
index 0000000000..f456b8fc10
--- /dev/null
+++ b/modules/md/md_store_fs.c
@@ -0,0 +1,727 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <apr_lib.h>
+#include <apr_file_info.h>
+#include <apr_file_io.h>
+#include <apr_fnmatch.h>
+#include <apr_hash.h>
+#include <apr_strings.h>
+
+#include "md.h"
+#include "md_crypt.h"
+#include "md_json.h"
+#include "md_log.h"
+#include "md_store.h"
+#include "md_store_fs.h"
+#include "md_util.h"
+#include "md_version.h"
+
+/**************************************************************************************************/
+/* file system based implementation of md_store_t */
+
+typedef struct {
+    apr_fileperms_t dir;
+    apr_fileperms_t file;
+} perms_t;
+
+typedef struct md_store_fs_t md_store_fs_t;
+struct md_store_fs_t {
+    md_store_t s;
+    
+    const char *base;       /* base directory of store */
+    perms_t def_perms;
+    perms_t group_perms[MD_SG_COUNT];
+    md_store_fs_cb *event_cb;
+    void *event_baton;
+    
+    const unsigned char *key;
+    apr_size_t key_len;
+    int plain_pkey[MD_SG_COUNT];
+    
+    int port_80;
+    int port_443;
+
+    const unsigned char *dupkey;
+};
+
+#define FS_STORE(store)     (md_store_fs_t*)(((char*)store)-offsetof(md_store_fs_t, s))
+#define FS_STORE_JSON       "md_store.json"
+#define FS_STORE_KLEN       48
+
+static apr_status_t fs_load(md_store_t *store, md_store_group_t group, 
+                            const char *name, const char *aspect,  
+                            md_store_vtype_t vtype, void **pvalue, apr_pool_t *p);
+static apr_status_t fs_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                            const char *name, const char *aspect,  
+                            md_store_vtype_t vtype, void *value, int create);
+static apr_status_t fs_remove(md_store_t *store, md_store_group_t group, 
+                              const char *name, const char *aspect, 
+                              apr_pool_t *p, int force);
+static apr_status_t fs_purge(md_store_t *store, apr_pool_t *p, 
+                             md_store_group_t group, const char *name);
+static apr_status_t fs_move(md_store_t *store, apr_pool_t *p, 
+                            md_store_group_t from, md_store_group_t to, 
+                            const char *name, int archive);
+static apr_status_t fs_iterate(md_store_inspect *inspect, void *baton, md_store_t *store, 
+                               apr_pool_t *p, md_store_group_t group,  const char *pattern,
+                               const char *aspect, md_store_vtype_t vtype);
+
+static apr_status_t fs_get_fname(const char **pfname, 
+                                 md_store_t *store, md_store_group_t group, 
+                                 const char *name, const char *aspect, 
+                                 apr_pool_t *p);
+
+static apr_status_t init_store_file(md_store_fs_t *s_fs, const char *fname, 
+                                    apr_pool_t *p, apr_pool_t *ptemp)
+{
+    md_json_t *json = md_json_create(p);
+    const char *key64;
+    apr_status_t rv;
+    unsigned char key[FS_STORE_KLEN];
+    int i;
+    
+    md_json_sets(MOD_MD_VERSION, json, MD_KEY_VERSION, NULL);
+
+    /*if (APR_SUCCESS != (rv = md_rand_bytes(key, sizeof(key), p))) {
+        return rv;
+    }*/
+    for (i = 0; i < FS_STORE_KLEN; ++i) {
+        key[i] = 'a' + (i % 26);
+    } 
+
+    s_fs->key_len = sizeof(key);
+    s_fs->key = apr_pcalloc(p, sizeof(key) + 1);
+    memcpy((void*)s_fs->key, key, sizeof(key));
+    s_fs->dupkey = apr_pmemdup(p, key, sizeof(key));
+        
+    key64 = md_util_base64url_encode((char *)key, sizeof(key), ptemp);
+    md_json_sets(key64, json, MD_KEY_KEY, NULL);
+    
+    rv = md_json_fcreatex(json, ptemp, MD_JSON_FMT_INDENT, fname, MD_FPROT_F_UONLY);
+    memset((char*)key64, 0, strlen(key64));
+
+    assert(memcmp(s_fs->key, s_fs->dupkey, FS_STORE_KLEN) == 0);
+    return rv;
+}
+
+static apr_status_t read_store_file(md_store_fs_t *s_fs, const char *fname, 
+                                    apr_pool_t *p, apr_pool_t *ptemp)
+{
+    md_json_t *json;
+    const char *s, *key64;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = md_json_readf(&json, p, fname))) {
+        s = md_json_gets(json, MD_KEY_VERSION, NULL);
+        if (!s) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "missing key: %s", MD_KEY_VERSION);
+            return APR_EINVAL;
+        }
+        if (strcmp(MOD_MD_VERSION, s) < 0) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "version too new: %s", s);
+            return APR_EINVAL;
+        }
+        /* TODO: need to migrate store? */
+        
+        key64 = md_json_dups(p, json, MD_KEY_KEY, NULL);
+        if (!key64) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "missing key: %s", MD_KEY_KEY);
+            return APR_EINVAL;
+        }
+        
+        s_fs->key_len = md_util_base64url_decode((const char **)&s_fs->key, key64, p);
+        if (s_fs->key_len < FS_STORE_KLEN) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, 0, p, "key too short: %d", s_fs->key_len);
+            return APR_EINVAL;
+        }
+        s_fs->dupkey = apr_pmemdup(p, s_fs->key, FS_STORE_KLEN);
+    }
+    return rv;
+}
+
+static apr_status_t setup_store_file(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_fs_t *s_fs = baton;
+    const char *fname;
+    apr_status_t rv;
+
+    s_fs->plain_pkey[MD_SG_DOMAINS] = 1;
+    s_fs->plain_pkey[MD_SG_TMP] = 1;
+    
+    rv = md_util_path_merge(&fname, ptemp, s_fs->base, FS_STORE_JSON, NULL);
+    if (APR_SUCCESS != rv) {
+        return rv;
+    }
+    
+read:
+    if (APR_SUCCESS == (rv = md_util_is_file(fname, ptemp))) {
+        rv = read_store_file(s_fs, fname, p, ptemp);
+    }
+    else if (APR_STATUS_IS_ENOENT(rv)) {
+        rv = init_store_file(s_fs, fname, p, ptemp);
+        if (APR_STATUS_IS_EEXIST(rv)) {
+            goto read;
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_store_fs_init(md_store_t **pstore, apr_pool_t *p, const char *path)
+{
+    md_store_fs_t *s_fs;
+    apr_status_t rv = APR_SUCCESS;
+    
+    s_fs = apr_pcalloc(p, sizeof(*s_fs));
+
+    s_fs->s.load = fs_load;
+    s_fs->s.save = fs_save;
+    s_fs->s.remove = fs_remove;
+    s_fs->s.move = fs_move;
+    s_fs->s.purge = fs_purge;
+    s_fs->s.iterate = fs_iterate;
+    s_fs->s.get_fname = fs_get_fname;
+    
+    /* by default, everything is only readable by the current user */ 
+    s_fs->def_perms.dir = MD_FPROT_D_UONLY;
+    s_fs->def_perms.file = MD_FPROT_F_UONLY;
+
+    /* Account information needs to be accessible to httpd child processes.
+     * private keys are, similar to staging, encrypted. */
+    s_fs->group_perms[MD_SG_ACCOUNTS].dir = MD_FPROT_D_UALL_WREAD;
+    s_fs->group_perms[MD_SG_ACCOUNTS].file = MD_FPROT_F_UALL_WREAD;
+    s_fs->group_perms[MD_SG_STAGING].dir = MD_FPROT_D_UALL_WREAD;
+    s_fs->group_perms[MD_SG_STAGING].file = MD_FPROT_F_UALL_WREAD;
+    /* challenges dir and files are readable by all, no secrets involved */ 
+    s_fs->group_perms[MD_SG_CHALLENGES].dir = MD_FPROT_D_UALL_WREAD;
+    s_fs->group_perms[MD_SG_CHALLENGES].file = MD_FPROT_F_UALL_WREAD;
+
+    s_fs->base = apr_pstrdup(p, path);
+    
+    if (APR_SUCCESS != (rv = md_util_is_dir(s_fs->base, p))) {
+        if (APR_STATUS_IS_ENOENT(rv)) {
+            rv = apr_dir_make_recursive(s_fs->base, s_fs->def_perms.dir, p);
+            if (APR_SUCCESS == rv) {
+                rv = apr_file_perms_set(s_fs->base, MD_FPROT_D_UALL_WREAD);
+                if (APR_STATUS_IS_ENOTIMPL(rv)) {
+                    rv = APR_SUCCESS;
+                }
+            }
+        }
+    }
+    rv = md_util_pool_vdo(setup_store_file, s_fs, p, NULL);
+    
+    if (APR_SUCCESS != rv) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, p, "init fs store at %s", path);
+    }
+    *pstore = (rv == APR_SUCCESS)? &(s_fs->s) : NULL;
+    return rv;
+}
+
+apr_status_t md_store_fs_default_perms_set(md_store_t *store, 
+                                           apr_fileperms_t file_perms,
+                                           apr_fileperms_t dir_perms)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    
+    s_fs->def_perms.file = file_perms;
+    s_fs->def_perms.dir = dir_perms;
+    return APR_SUCCESS;
+}
+
+apr_status_t md_store_fs_group_perms_set(md_store_t *store, md_store_group_t group, 
+                                         apr_fileperms_t file_perms,
+                                         apr_fileperms_t dir_perms)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    
+    if (group >= (sizeof(s_fs->group_perms)/sizeof(s_fs->group_perms[0]))) {
+        return APR_ENOTIMPL;
+    }
+    s_fs->group_perms[group].file = file_perms;
+    s_fs->group_perms[group].dir = dir_perms;
+    return APR_SUCCESS;
+}
+
+apr_status_t md_store_fs_set_event_cb(struct md_store_t *store, md_store_fs_cb *cb, void *baton)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    
+    s_fs->event_cb = cb;
+    s_fs->event_baton = baton;
+    return APR_SUCCESS;
+}
+
+static const perms_t *gperms(md_store_fs_t *s_fs, md_store_group_t group)
+{
+    if (group >= (sizeof(s_fs->group_perms)/sizeof(s_fs->group_perms[0]))
+        || !s_fs->group_perms[group].dir) {
+        return &s_fs->def_perms;
+    }
+    return &s_fs->group_perms[group];
+}
+
+static apr_status_t fs_get_fname(const char **pfname, 
+                                 md_store_t *store, md_store_group_t group, 
+                                 const char *name, const char *aspect, 
+                                 apr_pool_t *p)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    if (group == MD_SG_NONE) {
+        return md_util_path_merge(pfname, p, s_fs->base, aspect, NULL);
+    }
+    return md_util_path_merge(pfname, p, 
+                              s_fs->base, md_store_group_name(group), name, aspect, NULL);
+}
+
+static apr_status_t fs_get_dname(const char **pdname, 
+                                 md_store_t *store, md_store_group_t group, 
+                                 const char *name, apr_pool_t *p)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    if (group == MD_SG_NONE) {
+        *pdname = s_fs->base;
+        return APR_SUCCESS;
+    }
+    return md_util_path_merge(pdname, p, s_fs->base, md_store_group_name(group), name, NULL);
+}
+
+static void get_pass(const char **ppass, apr_size_t *plen, 
+                     md_store_fs_t *s_fs, md_store_group_t group)
+{
+    if (s_fs->plain_pkey[group]) {
+        *ppass = NULL;
+        *plen = 0;
+    }
+    else {
+        assert(memcmp(s_fs->key, s_fs->dupkey, FS_STORE_KLEN) == 0);
+        *ppass = (const char *)s_fs->key;
+        *plen = s_fs->key_len;
+    }
+}
+ 
+static apr_status_t fs_fload(void **pvalue, md_store_fs_t *s_fs, const char *fpath, 
+                             md_store_group_t group, md_store_vtype_t vtype, 
+                             apr_pool_t *p, apr_pool_t *ptemp)
+{
+    apr_status_t rv;
+    const char *pass;
+    apr_size_t pass_len;
+    
+    if (pvalue != NULL) {
+        switch (vtype) {
+            case MD_SV_TEXT:
+                rv = md_text_fread8k((const char **)pvalue, p, fpath);
+                break;
+            case MD_SV_JSON:
+                rv = md_json_readf((md_json_t **)pvalue, p, fpath);
+                break;
+            case MD_SV_CERT:
+                rv = md_cert_fload((md_cert_t **)pvalue, p, fpath);
+                break;
+            case MD_SV_PKEY:
+                get_pass(&pass, &pass_len, s_fs, group);
+                rv = md_pkey_fload((md_pkey_t **)pvalue, p, pass, pass_len, fpath);
+                break;
+            case MD_SV_CHAIN:
+                rv = md_chain_fload((apr_array_header_t **)pvalue, p, fpath);
+                break;
+            default:
+                rv = APR_ENOTIMPL;
+                break;
+        }
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE2, rv, ptemp, 
+                      "loading type %d from %s", vtype, fpath);
+    }
+    else { /* check for existence only */
+        rv = md_util_is_file(fpath, p);
+    }
+    return rv;
+}
+
+static apr_status_t pfs_load(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_fs_t *s_fs = baton;
+    const char *fpath, *name, *aspect;
+    md_store_vtype_t vtype;
+    md_store_group_t group;
+    void **pvalue;
+    apr_status_t rv;
+    
+    group = va_arg(ap, int);
+    name = va_arg(ap, const char *);
+    aspect = va_arg(ap, const char *);
+    vtype = va_arg(ap, int);
+    pvalue= va_arg(ap, void **);
+        
+    rv = fs_get_fname(&fpath, &s_fs->s, group, name, aspect, ptemp);
+    if (APR_SUCCESS == rv) {
+        rv = fs_fload(pvalue, s_fs, fpath, group, vtype, p, ptemp);
+    }
+    return rv;
+}
+
+static apr_status_t dispatch(md_store_fs_t *s_fs, md_store_fs_ev_t ev, int group, 
+                             const char *fname, apr_filetype_e ftype, apr_pool_t *p)
+{
+    if (s_fs->event_cb) {
+        return s_fs->event_cb(s_fs->event_baton, &s_fs->s, MD_S_FS_EV_CREATED, 
+                              group, fname, ftype, p);
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t mk_group_dir(const char **pdir, md_store_fs_t *s_fs, 
+                                 md_store_group_t group, const char *name,
+                                 apr_pool_t *p)
+{
+    const perms_t *perms;
+    apr_status_t rv;
+    
+    perms = gperms(s_fs, group);
+
+    if (APR_SUCCESS == (rv = fs_get_dname(pdir, &s_fs->s, group, name, p))
+        && (MD_SG_NONE != group)) {
+        if (APR_SUCCESS != md_util_is_dir(*pdir, p)) {
+            if (APR_SUCCESS == (rv = apr_dir_make_recursive(*pdir, perms->dir, p))) {
+                rv = dispatch(s_fs, MD_S_FS_EV_CREATED, group, *pdir, APR_DIR, p);
+            }
+        }
+        else {
+            /* already exists */
+        }
+        
+        if (APR_SUCCESS == rv) {
+            rv = apr_file_perms_set(*pdir, perms->dir);
+            md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, p, "mk_group_dir %s perm set", *pdir);
+            if (APR_STATUS_IS_ENOTIMPL(rv)) {
+                rv = APR_SUCCESS;
+            }
+        }
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, p, "mk_group_dir %d %s", group, name);
+    return rv;
+}
+ 
+ 
+static apr_status_t pfs_save(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_fs_t *s_fs = baton;
+    const char *gdir, *dir, *fpath, *name, *aspect;
+    md_store_vtype_t vtype;
+    md_store_group_t group;
+    void *value;
+    int create;
+    apr_status_t rv;
+    const perms_t *perms;
+    const char *pass;
+    apr_size_t pass_len;
+    
+    group = va_arg(ap, int);
+    name = va_arg(ap, const char*);
+    aspect = va_arg(ap, const char*);
+    vtype = va_arg(ap, int);
+    value = va_arg(ap, void *);
+    create = va_arg(ap, int);
+    
+    perms = gperms(s_fs, group);
+    
+    if (APR_SUCCESS == (rv = mk_group_dir(&gdir, s_fs, group, NULL, p)) 
+        && APR_SUCCESS == (rv = mk_group_dir(&dir, s_fs, group, name, p))
+        && APR_SUCCESS == (rv = md_util_path_merge(&fpath, ptemp, dir, aspect, NULL))) {
+        
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, ptemp, "storing in %s", fpath);
+        switch (vtype) {
+            case MD_SV_TEXT:
+                rv = (create? md_text_fcreatex(fpath, perms->file, p, value)
+                      : md_text_freplace(fpath, perms->file, p, value));
+                break;
+            case MD_SV_JSON:
+                rv = (create? md_json_fcreatex((md_json_t *)value, p, MD_JSON_FMT_INDENT, 
+                                               fpath, perms->file)
+                      : md_json_freplace((md_json_t *)value, p, MD_JSON_FMT_INDENT, 
+                                         fpath, perms->file));
+                break;
+            case MD_SV_CERT:
+                rv = md_cert_fsave((md_cert_t *)value, ptemp, fpath, perms->file);
+                break;
+            case MD_SV_PKEY:
+                /* Take care that we write private key with access only to the user,
+                 * unless we write the key encrypted */
+                get_pass(&pass, &pass_len, s_fs, group);
+                rv = md_pkey_fsave((md_pkey_t *)value, ptemp, pass, pass_len, 
+                                   fpath, (pass && pass_len)? perms->file : MD_FPROT_F_UONLY);
+                break;
+            case MD_SV_CHAIN:
+                rv = md_chain_fsave((apr_array_header_t*)value, ptemp, fpath, perms->file);
+                break;
+            default:
+                return APR_ENOTIMPL;
+        }
+        if (APR_SUCCESS == rv) {
+            rv = dispatch(s_fs, MD_S_FS_EV_CREATED, group, fpath, APR_REG, p);
+        }
+    }
+    return rv;
+}
+
+static apr_status_t pfs_remove(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_fs_t *s_fs = baton;
+    const char *dir, *name, *fpath, *groupname, *aspect;
+    apr_status_t rv;
+    int force;
+    apr_finfo_t info;
+    md_store_group_t group;
+    
+    group = va_arg(ap, int);
+    name = va_arg(ap, const char*);
+    aspect = va_arg(ap, const char *);
+    force = va_arg(ap, int);
+    
+    groupname = md_store_group_name(group);
+    
+    if (APR_SUCCESS == (rv = md_util_path_merge(&dir, ptemp, s_fs->base, groupname, name, NULL))
+        && APR_SUCCESS == (rv = md_util_path_merge(&fpath, ptemp, dir, aspect, NULL))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, 0, ptemp, "start remove of md %s/%s/%s", 
+                      groupname, name, aspect);
+
+        if (APR_SUCCESS != (rv = apr_stat(&info, dir, APR_FINFO_TYPE, ptemp))) {
+            if (APR_ENOENT == rv && force) {
+                return APR_SUCCESS;
+            }
+            return rv;
+        }
+    
+        rv = apr_file_remove(fpath, ptemp);
+        if (APR_ENOENT == rv && force) {
+            rv = APR_SUCCESS;
+        }
+    }
+    return rv;
+}
+
+static apr_status_t fs_load(md_store_t *store, md_store_group_t group, 
+                            const char *name, const char *aspect,  
+                            md_store_vtype_t vtype, void **pvalue, apr_pool_t *p)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    return md_util_pool_vdo(pfs_load, s_fs, p, group, name, aspect, vtype, pvalue, NULL);
+}
+
+static apr_status_t fs_save(md_store_t *store, apr_pool_t *p, md_store_group_t group, 
+                            const char *name, const char *aspect,  
+                            md_store_vtype_t vtype, void *value, int create)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    return md_util_pool_vdo(pfs_save, s_fs, p, group, name, aspect, 
+                            vtype, value, create, NULL);
+}
+
+static apr_status_t fs_remove(md_store_t *store, md_store_group_t group, 
+                              const char *name, const char *aspect, 
+                              apr_pool_t *p, int force)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    return md_util_pool_vdo(pfs_remove, s_fs, p, group, name, aspect, force, NULL);
+}
+
+static apr_status_t pfs_purge(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_fs_t *s_fs = baton;
+    const char *dir, *name, *groupname;
+    md_store_group_t group;
+    apr_status_t rv;
+    
+    group = va_arg(ap, int);
+    name = va_arg(ap, const char*);
+    
+    groupname = md_store_group_name(group);
+
+    if (APR_SUCCESS == (rv = md_util_path_merge(&dir, ptemp, s_fs->base, groupname, name, NULL))) {
+        /* Remove all files in dir, there should be no sub-dirs */
+        rv = md_util_rm_recursive(dir, ptemp, 1);
+    }
+    md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, ptemp, "purge %s/%s (%s)", groupname, name, dir);
+    return APR_SUCCESS;
+}
+
+static apr_status_t fs_purge(md_store_t *store, apr_pool_t *p, 
+                             md_store_group_t group, const char *name)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    return md_util_pool_vdo(pfs_purge, s_fs, p, group, name, NULL);
+}
+
+/**************************************************************************************************/
+/* iteration */
+
+typedef struct {
+    md_store_fs_t *s_fs;
+    md_store_group_t group;
+    const char *pattern;
+    const char *aspect;
+    md_store_vtype_t vtype;
+    md_store_inspect *inspect;
+    void *baton;
+} inspect_ctx;
+
+static apr_status_t insp(void *baton, apr_pool_t *p, apr_pool_t *ptemp, 
+                         const char *dir, const char *name, apr_filetype_e ftype)
+{
+    inspect_ctx *ctx = baton;
+    apr_status_t rv;
+    void *value;
+    const char *fpath;
+    
+    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, ptemp, "inspecting value at: %s/%s", dir, name);
+    if (APR_SUCCESS == (rv = md_util_path_merge(&fpath, ptemp, dir, name, NULL))) {
+        rv = fs_fload(&value, ctx->s_fs, fpath, ctx->group, ctx->vtype, p, ptemp);
+        if (APR_SUCCESS == rv 
+            && !ctx->inspect(ctx->baton, name, ctx->aspect, ctx->vtype, value, ptemp)) {
+            return APR_EOF;
+        }
+    }
+    return rv;
+}
+
+static apr_status_t fs_iterate(md_store_inspect *inspect, void *baton, md_store_t *store, 
+                               apr_pool_t *p, md_store_group_t group, const char *pattern, 
+                               const char *aspect, md_store_vtype_t vtype)
+{
+    const char *groupname;
+    apr_status_t rv;
+    inspect_ctx ctx;
+    
+    ctx.s_fs = FS_STORE(store);
+    ctx.group = group;
+    ctx.pattern = pattern;
+    ctx.aspect = aspect;
+    ctx.vtype = vtype;
+    ctx.inspect = inspect;
+    ctx.baton = baton;
+    groupname = md_store_group_name(group);
+
+    rv = md_util_files_do(insp, &ctx, p, ctx.s_fs->base, groupname, ctx.pattern, aspect, NULL);
+    
+    return rv;
+}
+
+/**************************************************************************************************/
+/* moving */
+
+static apr_status_t pfs_move(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_store_fs_t *s_fs = baton;
+    const char *name, *from_group, *to_group, *from_dir, *to_dir, *arch_dir, *dir;
+    md_store_group_t from, to;
+    int archive;
+    apr_status_t rv;
+    
+    from = va_arg(ap, int);
+    to = va_arg(ap, int);
+    name = va_arg(ap, const char*);
+    archive = va_arg(ap, int);
+    
+    from_group = md_store_group_name(from);
+    to_group = md_store_group_name(to);
+    if (!strcmp(from_group, to_group)) {
+        return APR_EINVAL;
+    }
+
+    rv = md_util_path_merge(&from_dir, ptemp, s_fs->base, from_group, name, NULL);
+    if (APR_SUCCESS != rv) goto out;
+    rv = md_util_path_merge(&to_dir, ptemp, s_fs->base, to_group, name, NULL);
+    if (APR_SUCCESS != rv) goto out;
+    
+    if (APR_SUCCESS != (rv = md_util_is_dir(from_dir, ptemp))) {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, ptemp, "source is no dir: %s", from_dir);
+        goto out;
+    }
+    
+    rv = archive? md_util_is_dir(to_dir, ptemp) : APR_ENOENT;
+    if (APR_SUCCESS == rv) {
+        int n = 1;
+        const char *narch_dir;
+
+        rv = md_util_path_merge(&dir, ptemp, s_fs->base, md_store_group_name(MD_SG_ARCHIVE), NULL);
+        if (APR_SUCCESS != rv) goto out;
+        rv = apr_dir_make_recursive(dir, MD_FPROT_D_UONLY, ptemp); 
+        if (APR_SUCCESS != rv) goto out;
+        rv = md_util_path_merge(&arch_dir, ptemp, dir, name, NULL);
+        if (APR_SUCCESS != rv) goto out;
+        
+        while (1) {
+            narch_dir = apr_psprintf(ptemp, "%s.%d", arch_dir, n);
+            rv = apr_dir_make(narch_dir, MD_FPROT_D_UONLY, ptemp);
+            if (APR_SUCCESS == rv) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, ptemp, "using archive dir: %s", 
+                              narch_dir);
+                break;
+            }
+            else if (APR_EEXIST == rv) {
+                ++n;
+            }
+            else {
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, ptemp, "creating archive dir: %s", 
+                              narch_dir);
+                goto out;
+            }
+        } 
+        
+        if (APR_SUCCESS != (rv = apr_file_rename(to_dir, narch_dir, ptemp))) {
+                md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, ptemp, "rename from %s to %s", 
+                              to_dir, narch_dir);
+                goto out;
+        }
+        if (APR_SUCCESS != (rv = apr_file_rename(from_dir, to_dir, ptemp))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, ptemp, "moving %s to %s: %s", 
+                          from_dir, to_dir);
+            apr_file_rename(narch_dir, to_dir, ptemp);
+            goto out;
+        }
+        rv = dispatch(s_fs, MD_S_FS_EV_MOVED, to, to_dir, APR_DIR, ptemp);
+        if (APR_SUCCESS == rv) {
+            rv = dispatch(s_fs, MD_S_FS_EV_MOVED, MD_SG_ARCHIVE, narch_dir, APR_DIR, ptemp);
+        }
+    }
+    else if (APR_STATUS_IS_ENOENT(rv)) {
+        if (APR_SUCCESS != (rv = apr_file_rename(from_dir, to_dir, ptemp))) {
+            md_log_perror(MD_LOG_MARK, MD_LOG_ERR, rv, ptemp, "rename from %s to %s", 
+                          from_dir, to_dir);
+            goto out;
+        }
+    }
+    else {
+        md_log_perror(MD_LOG_MARK, MD_LOG_DEBUG, rv, ptemp, "target is no dir: %s", to_dir);
+        goto out;
+    }
+    
+out:
+    return rv;
+}
+
+static apr_status_t fs_move(md_store_t *store, apr_pool_t *p, 
+                            md_store_group_t from, md_store_group_t to, 
+                            const char *name, int archive)
+{
+    md_store_fs_t *s_fs = FS_STORE(store);
+    return md_util_pool_vdo(pfs_move, s_fs, p, from, to, name, archive, NULL);
+}
diff --git a/modules/md/md_store_fs.h b/modules/md/md_store_fs.h
new file mode 100644
index 0000000000..d2344be382
--- /dev/null
+++ b/modules/md/md_store_fs.h
@@ -0,0 +1,64 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_store_fs_h
+#define mod_md_md_store_fs_h
+
+struct md_store_t;
+
+/** 
+ * Default file permissions set by the store, user only read/write(/exec),
+ * if so supported by the apr. 
+ */
+#define MD_FPROT_F_UONLY      (APR_FPROT_UREAD|APR_FPROT_UWRITE)
+#define MD_FPROT_D_UONLY      (MD_FPROT_F_UONLY|APR_FPROT_UEXECUTE)
+
+/**
+ * User has all permission, group can read, other none
+ */
+#define MD_FPROT_F_UALL_GREAD (MD_FPROT_F_UONLY|APR_FPROT_GREAD)
+#define MD_FPROT_D_UALL_GREAD (MD_FPROT_D_UONLY|APR_FPROT_GREAD|APR_FPROT_GEXECUTE)
+
+/**
+ * User has all permission, group and others can read
+ */
+#define MD_FPROT_F_UALL_WREAD (MD_FPROT_F_UALL_GREAD|APR_FPROT_WREAD)
+#define MD_FPROT_D_UALL_WREAD (MD_FPROT_D_UALL_GREAD|APR_FPROT_WREAD|APR_FPROT_WEXECUTE)
+
+apr_status_t md_store_fs_init(struct md_store_t **pstore, apr_pool_t *p, 
+                              const char *path);
+
+
+apr_status_t md_store_fs_default_perms_set(struct md_store_t *store, 
+                                           apr_fileperms_t file_perms,
+                                           apr_fileperms_t dir_perms);
+apr_status_t md_store_fs_group_perms_set(struct md_store_t *store, 
+                                         md_store_group_t group, 
+                                         apr_fileperms_t file_perms,
+                                         apr_fileperms_t dir_perms);
+
+typedef enum {
+    MD_S_FS_EV_CREATED,
+    MD_S_FS_EV_MOVED,
+} md_store_fs_ev_t; 
+
+typedef apr_status_t md_store_fs_cb(void *baton, struct md_store_t *store,
+                                    md_store_fs_ev_t ev, int group, 
+                                    const char *fname, apr_filetype_e ftype,  
+                                    apr_pool_t *p);
+                                    
+apr_status_t md_store_fs_set_event_cb(struct md_store_t *store, md_store_fs_cb *cb, void *baton);
+
+#endif /* mod_md_md_store_fs_h */
diff --git a/modules/md/md_util.c b/modules/md/md_util.c
new file mode 100644
index 0000000000..ac531157f0
--- /dev/null
+++ b/modules/md/md_util.c
@@ -0,0 +1,1169 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+
+#include <apr_lib.h>
+#include <apr_strings.h>
+#include <apr_file_io.h>
+#include <apr_file_info.h>
+#include <apr_fnmatch.h>
+#include <apr_tables.h>
+#include <apr_time.h>
+#include <apr_uri.h>
+
+#include "md_log.h"
+#include "md_util.h"
+
+/**************************************************************************************************/
+/* pool utils */
+
+apr_status_t md_util_pool_do(md_util_action *cb, void *baton, apr_pool_t *p)
+{
+    apr_pool_t *ptemp;
+    apr_status_t rv = apr_pool_create(&ptemp, p);
+    if (APR_SUCCESS == rv) {
+        rv = cb(baton, p, ptemp);
+        
+        apr_pool_destroy(ptemp);
+    }
+    return rv;
+}
+ 
+static apr_status_t pool_vado(md_util_vaction *cb, void *baton, apr_pool_t *p, va_list ap)
+{
+    apr_pool_t *ptemp;
+    apr_status_t rv;
+    
+    rv = apr_pool_create(&ptemp, p);
+    if (APR_SUCCESS == rv) {
+        rv = cb(baton, p, ptemp, ap);
+        apr_pool_destroy(ptemp);
+    }
+    return rv;
+}
+ 
+apr_status_t md_util_pool_vdo(md_util_vaction *cb, void *baton, apr_pool_t *p, ...)
+{
+    va_list ap;
+    apr_status_t rv;
+    
+    va_start(ap, p);
+    rv = pool_vado(cb, baton, p, ap);
+    va_end(ap);
+    return rv;
+}
+ 
+/**************************************************************************************************/
+/* string related */
+
+char *md_util_str_tolower(char *s)
+{
+    char *orig = s;
+    while (*s) {
+        *s = apr_tolower(*s);
+        ++s;
+    }
+    return orig;
+}
+
+int md_array_str_index(const apr_array_header_t *array, const char *s, 
+                       int start, int case_sensitive)
+{
+    if (start >= 0) {
+        int i;
+        
+        for (i = start; i < array->nelts; i++) {
+            const char *p = APR_ARRAY_IDX(array, i, const char *);
+            if ((case_sensitive && !strcmp(p, s))
+                || (!case_sensitive && !apr_strnatcasecmp(p, s))) {
+                return i;
+            }
+        }
+    }
+    
+    return -1;
+}
+
+int md_array_str_eq(const struct apr_array_header_t *a1, 
+                    const struct apr_array_header_t *a2, int case_sensitive)
+{
+    int i;
+    const char *s1, *s2;
+    
+    if (a1 == a2) return 1;
+    if (!a1) return 0;
+    if (a1->nelts != a2->nelts) return 0;
+    for (i = 0; i < a1->nelts; ++i) {
+        s1 = APR_ARRAY_IDX(a1, i, const char *);
+        s2 = APR_ARRAY_IDX(a2, i, const char *);
+        if ((case_sensitive && strcmp(s1, s2))
+            || (!case_sensitive && apr_strnatcasecmp(s1, s2))) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+apr_array_header_t *md_array_str_clone(apr_pool_t *p, apr_array_header_t *src)
+{
+    apr_array_header_t *dest = apr_array_make(p, src->nelts, sizeof(const char*));
+    if (dest) {
+        int i;
+        for (i = 0; i < src->nelts; i++) {
+            const char *s = APR_ARRAY_IDX(src, i, const char *);
+            APR_ARRAY_PUSH(dest, const char *) = apr_pstrdup(p, s); 
+        }
+    }
+    return dest;
+}
+
+struct apr_array_header_t *md_array_str_compact(apr_pool_t *p, struct apr_array_header_t *src,
+                                                int case_sensitive)
+{
+    apr_array_header_t *dest = apr_array_make(p, src->nelts, sizeof(const char*));
+    if (dest) {
+        const char *s;
+        int i;
+        for (i = 0; i < src->nelts; ++i) {
+            s = APR_ARRAY_IDX(src, i, const char *);
+            if (md_array_str_index(dest, s, 0, case_sensitive) < 0) {
+                APR_ARRAY_PUSH(dest, char *) = md_util_str_tolower(apr_pstrdup(p, s));
+            }
+        }
+    }
+    return dest;
+}
+
+apr_array_header_t *md_array_str_remove(apr_pool_t *p, apr_array_header_t *src, 
+                                        const char *exclude, int case_sensitive)
+{
+    apr_array_header_t *dest = apr_array_make(p, src->nelts, sizeof(const char*));
+    if (dest) {
+        int i;
+        for (i = 0; i < src->nelts; i++) {
+            const char *s = APR_ARRAY_IDX(src, i, const char *);
+            if (!exclude 
+                || (case_sensitive && strcmp(exclude, s))
+                || (!case_sensitive && apr_strnatcasecmp(exclude, s))) {
+                APR_ARRAY_PUSH(dest, const char *) = apr_pstrdup(p, s); 
+            }
+        }
+    }
+    return dest;
+}
+
+int md_array_str_add_missing(apr_array_header_t *dest, apr_array_header_t *src, int case_sensitive)
+{
+    int i, added = 0;
+    for (i = 0; i < src->nelts; i++) {
+        const char *s = APR_ARRAY_IDX(src, i, const char *);
+        if (md_array_str_index(dest, s, 0, case_sensitive) < 0) {
+            APR_ARRAY_PUSH(dest, const char *) = s;
+            ++added; 
+        }
+    }
+    return added;
+}
+
+/**************************************************************************************************/
+/* file system related */
+
+apr_status_t md_util_fopen(FILE **pf, const char *fn, const char *mode)
+{
+    *pf = fopen(fn, mode);
+    if (*pf == NULL) {
+        return errno;
+    }
+
+    return APR_SUCCESS;
+}
+
+apr_status_t md_util_fcreatex(apr_file_t **pf, const char *fn, 
+                              apr_fileperms_t perms, apr_pool_t *p)
+{
+    return apr_file_open(pf, fn, (APR_FOPEN_WRITE|APR_FOPEN_CREATE|APR_FOPEN_EXCL),
+                         perms, p);
+}
+
+apr_status_t md_util_is_dir(const char *path, apr_pool_t *pool)
+{
+    apr_finfo_t info;
+    apr_status_t rv = apr_stat(&info, path, APR_FINFO_TYPE, pool);
+    if (rv == APR_SUCCESS) {
+        rv = (info.filetype == APR_DIR)? APR_SUCCESS : APR_EINVAL;
+    }
+    return rv;
+}
+
+apr_status_t md_util_is_file(const char *path, apr_pool_t *pool)
+{
+    apr_finfo_t info;
+    apr_status_t rv = apr_stat(&info, path, APR_FINFO_TYPE, pool);
+    if (rv == APR_SUCCESS) {
+        rv = (info.filetype == APR_REG)? APR_SUCCESS : APR_EINVAL;
+    }
+    return rv;
+}
+
+apr_status_t md_util_path_merge(const char **ppath, apr_pool_t *p, ...)
+{
+    const char *segment, *path;
+    va_list ap;
+    apr_status_t rv = APR_SUCCESS;
+    
+    va_start(ap, p);
+    path = va_arg(ap, char *);
+    while (path && APR_SUCCESS == rv && (segment = va_arg(ap, char *))) {
+        rv = apr_filepath_merge((char **)&path, path, segment, APR_FILEPATH_SECUREROOT , p);
+    }
+    va_end(ap);
+    
+    *ppath = (APR_SUCCESS == rv)? (path? path : "") : NULL;
+    return rv;
+}
+
+apr_status_t md_util_freplace(const char *fpath, apr_fileperms_t perms, apr_pool_t *p, 
+                              md_util_file_cb *write_cb, void *baton)
+{
+    apr_status_t rv = APR_EEXIST;
+    apr_file_t *f;
+    const char *tmp;
+    int i, max;
+    
+    tmp = apr_psprintf(p, "%s.tmp", fpath);
+    i = 0; max = 20;
+creat:
+    while (i < max && APR_EEXIST == (rv = md_util_fcreatex(&f, tmp, perms, p))) {
+        ++i;
+        apr_sleep(apr_time_msec(50));
+    } 
+    if (APR_EEXIST == rv 
+        && APR_SUCCESS == (rv = apr_file_remove(tmp, p))
+        && max <= 20) {
+        max *= 2;
+        goto creat;
+    }
+    
+    if (APR_SUCCESS == rv) {
+        rv = write_cb(baton, f, p);
+        apr_file_close(f);
+        
+        if (APR_SUCCESS == rv) {
+            rv = apr_file_rename(tmp, fpath, p);
+            if (APR_SUCCESS != rv) {
+                apr_file_remove(tmp, p);
+            }
+        }
+    }
+    return rv;
+}                            
+
+/**************************************************************************************************/
+/* text files */
+
+apr_status_t md_text_fread8k(const char **ptext, apr_pool_t *p, const char *fpath)
+{
+    apr_status_t rv;
+    apr_file_t *f;
+    char buffer[8 * 1024];
+
+    *ptext = NULL;
+    if (APR_SUCCESS == (rv = apr_file_open(&f, fpath, APR_FOPEN_READ, 0, p))) {
+        apr_size_t blen = sizeof(buffer)/sizeof(buffer[0]) - 1;
+        rv = apr_file_read_full(f, buffer, blen, &blen);
+        if (APR_SUCCESS == rv || APR_STATUS_IS_EOF(rv)) {
+            *ptext = apr_pstrndup(p, buffer, blen);
+            rv = APR_SUCCESS;
+        }
+        apr_file_close(f);
+    }
+    return rv;
+}
+
+static apr_status_t write_text(void *baton, struct apr_file_t *f, apr_pool_t *p)
+{
+    const char *text = baton;
+    apr_size_t len = strlen(text);
+    return apr_file_write_full(f, text, len, &len);
+}
+
+apr_status_t md_text_fcreatex(const char *fpath, apr_fileperms_t perms, 
+                              apr_pool_t *p, const char *text)
+{
+    apr_status_t rv;
+    apr_file_t *f;
+    
+    rv = md_util_fcreatex(&f, fpath, perms, p);
+    if (APR_SUCCESS == rv) {
+        rv = write_text((void*)text, f, p);
+        apr_file_close(f);
+    }
+    return rv;
+}
+
+apr_status_t md_text_freplace(const char *fpath, apr_fileperms_t perms, 
+                              apr_pool_t *p, const char *text)
+{
+    return md_util_freplace(fpath, perms, p, write_text, (void*)text);
+}
+
+typedef struct {
+    const char *path;
+    apr_array_header_t *patterns;
+    int follow_links;
+    void *baton;
+    md_util_fdo_cb *cb;
+} md_util_fwalk_t;
+
+static apr_status_t rm_recursive(const char *fpath, apr_pool_t *p, int max_level)
+{
+    apr_finfo_t info;
+    apr_status_t rv;
+    const char *npath;
+    
+    if (APR_SUCCESS != (rv = apr_stat(&info, fpath, (APR_FINFO_TYPE|APR_FINFO_LINK), p))) {
+        return rv;
+    }
+    
+    if (info.filetype == APR_DIR) {
+        if (max_level > 0) {
+            apr_dir_t *d;
+            
+            if (APR_SUCCESS == (rv = apr_dir_open(&d, fpath, p))) {
+            
+                while (APR_SUCCESS == rv && 
+                       APR_SUCCESS == (rv = apr_dir_read(&info, APR_FINFO_TYPE, d))) {
+                    if (!strcmp(".", info.name) || !strcmp("..", info.name)) {
+                        continue;
+                    }
+                    
+                    rv = md_util_path_merge(&npath, p, fpath, info.name, NULL);
+                    if (APR_SUCCESS == rv) {
+                        rv = rm_recursive(npath, p, max_level - 1);
+                    }
+                }
+                apr_dir_close(d);
+                if (APR_STATUS_IS_ENOENT(rv)) {
+                    rv = APR_SUCCESS;
+                }
+            }
+        }
+        if (APR_SUCCESS == rv) {
+            rv = apr_dir_remove(fpath, p);
+        }
+    }
+    else {
+        rv = apr_file_remove(fpath, p);
+    }
+    return rv;
+}
+
+static apr_status_t prm_recursive(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    int max_level = va_arg(ap, int);
+    return rm_recursive(baton, ptemp, max_level); 
+}
+
+apr_status_t md_util_rm_recursive(const char *fpath, apr_pool_t *p, int max_level)
+{
+    return md_util_pool_vdo(prm_recursive, (void*)fpath, p, max_level, NULL);
+}
+
+static apr_status_t match_and_do(md_util_fwalk_t *ctx, const char *path, int depth, 
+                                 apr_pool_t *p, apr_pool_t *ptemp)
+{
+    apr_status_t rv = APR_SUCCESS;
+    const char *pattern, *npath;
+    apr_dir_t *d;
+    apr_finfo_t finfo;
+    int ndepth = depth + 1;
+    apr_int32_t wanted = (APR_FINFO_TYPE);
+
+    if (depth >= ctx->patterns->nelts) {
+        return APR_SUCCESS;
+    }
+    pattern = APR_ARRAY_IDX(ctx->patterns, depth, const char *);
+    
+    rv = apr_dir_open(&d, path, ptemp);
+    if (APR_SUCCESS != rv) {
+        return rv;
+    }
+    
+    while (APR_SUCCESS == (rv = apr_dir_read(&finfo, wanted, d))) {
+        if (!strcmp(".", finfo.name) || !strcmp("..", finfo.name)) {
+            continue;
+        } 
+        if (APR_SUCCESS == apr_fnmatch(pattern, finfo.name, 0)) {
+            if (ndepth < ctx->patterns->nelts) {
+                if (APR_DIR == finfo.filetype) { 
+                    /* deeper and deeper, irgendwo in der tiefe leuchtet ein licht */
+                    rv = md_util_path_merge(&npath, ptemp, path, finfo.name, NULL);
+                    if (APR_SUCCESS == rv) {
+                        rv = match_and_do(ctx, npath, ndepth, p, ptemp);
+                    }
+                }
+            }
+            else {
+                rv = ctx->cb(ctx->baton, p, ptemp, path, finfo.name, finfo.filetype);
+            }
+        }
+        if (APR_SUCCESS != rv) {
+            break;
+        }
+    }
+
+    if (APR_STATUS_IS_ENOENT(rv)) {
+        rv = APR_SUCCESS;
+    }
+
+    apr_dir_close(d);
+    return rv;
+}
+
+static apr_status_t files_do_start(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap)
+{
+    md_util_fwalk_t *ctx = baton;
+    const char *segment;
+
+    ctx->patterns = apr_array_make(ptemp, 5, sizeof(const char*));
+    
+    segment = va_arg(ap, char *);
+    while (segment) {
+        APR_ARRAY_PUSH(ctx->patterns, const char *) = segment;
+        segment = va_arg(ap, char *);
+    }
+    
+    return match_and_do(ctx, ctx->path, 0, p, ptemp);
+}
+
+apr_status_t md_util_files_do(md_util_fdo_cb *cb, void *baton, apr_pool_t *p,
+                              const char *path, ...)
+{
+    apr_status_t rv;
+    va_list ap;
+    md_util_fwalk_t ctx;
+
+    memset(&ctx, 0, sizeof(ctx));
+    ctx.path = path;
+    ctx.follow_links = 1;
+    ctx.cb = cb;
+    ctx.baton = baton;
+    
+    va_start(ap, path);
+    rv = pool_vado(files_do_start, &ctx, p, ap);
+    va_end(ap);
+    
+    return rv;
+}
+
+static apr_status_t tree_do(void *baton, apr_pool_t *p, apr_pool_t *ptemp, const char *path)
+{
+    md_util_fwalk_t *ctx = baton;
+
+    apr_status_t rv = APR_SUCCESS;
+    const char *name, *fpath;
+    apr_filetype_e ftype;
+    apr_dir_t *d;
+    apr_int32_t wanted = APR_FINFO_TYPE;
+    apr_finfo_t finfo;
+
+    if (APR_SUCCESS == (rv = apr_dir_open(&d, path, ptemp))) {
+        while (APR_SUCCESS == (rv = apr_dir_read(&finfo, wanted, d))) {
+            name = finfo.name;
+            if (!strcmp(".", name) || !strcmp("..", name)) {
+                continue;
+            }
+
+            fpath = NULL;
+            ftype = finfo.filetype;
+            
+            if (APR_LNK == ftype && ctx->follow_links) {
+                rv = md_util_path_merge(&fpath, ptemp, path, name, NULL);
+                if (APR_SUCCESS == rv) {
+                    rv = apr_stat(&finfo, ctx->path, wanted, ptemp);
+                }
+            }
+            
+            if (APR_DIR == finfo.filetype) {
+                if (!fpath) {
+                    rv = md_util_path_merge(&fpath, ptemp, path, name, NULL);
+                }
+                if (APR_SUCCESS == rv) {
+                    rv = tree_do(ctx, p, ptemp, fpath);
+                    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, rv, ptemp, "dir cb(%s/%s)", 
+                                  path, name);
+                    rv = ctx->cb(ctx->baton, p, ptemp, path, name, ftype);
+                }
+            }
+            else {
+                md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, rv, ptemp, "file cb(%s/%s)", 
+                              path, name);
+                rv = ctx->cb(ctx->baton, p, ptemp, path, name, finfo.filetype);
+            }
+        }
+
+        apr_dir_close(d);
+        
+        if (APR_STATUS_IS_ENOENT(rv)) {
+            rv = APR_SUCCESS;
+        }
+    }
+    return rv;
+}
+
+static apr_status_t tree_start_do(void *baton, apr_pool_t *p, apr_pool_t *ptemp)
+{
+    md_util_fwalk_t *ctx = baton;
+    apr_finfo_t info;
+    apr_status_t rv;
+    apr_int32_t wanted = ctx->follow_links? APR_FINFO_TYPE : (APR_FINFO_TYPE|APR_FINFO_LINK);
+    
+    rv = apr_stat(&info, ctx->path, wanted, ptemp);
+    if (rv == APR_SUCCESS) {
+        switch (info.filetype) {
+            case APR_DIR:
+                rv = tree_do(ctx, p, ptemp, ctx->path);
+                break;
+            default:
+                rv = APR_EINVAL;
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_util_tree_do(md_util_fdo_cb *cb, void *baton, apr_pool_t *p, 
+                             const char *path, int follow_links)
+{
+    apr_status_t rv;
+    md_util_fwalk_t ctx;
+
+    memset(&ctx, 0, sizeof(ctx));
+    ctx.path = path;
+    ctx.follow_links = follow_links;
+    ctx.cb = cb;
+    ctx.baton = baton;
+    
+    rv = md_util_pool_do(tree_start_do, &ctx, p);
+    
+    return rv;
+}
+
+static apr_status_t rm_cb(void *baton, apr_pool_t *p, apr_pool_t *ptemp, 
+                          const char *path, const char *name, apr_filetype_e ftype)
+{
+    apr_status_t rv;
+    const char *fpath;
+    
+    rv = md_util_path_merge(&fpath, ptemp, path, name, NULL);
+    if (APR_SUCCESS == rv) {
+        if (APR_DIR == ftype) {
+            rv = apr_dir_remove(fpath, ptemp);
+        }
+        else {
+            rv = apr_file_remove(fpath, ptemp);
+        }
+    }
+    return rv;
+}
+
+apr_status_t md_util_ftree_remove(const char *path, apr_pool_t *p)
+{
+    apr_status_t rv = md_util_tree_do(rm_cb, NULL, p, path, 0);
+    if (APR_SUCCESS == rv) {
+        rv = apr_dir_remove(path, p);
+    }
+    return rv;
+}
+
+/* DNS name checks ********************************************************************************/
+
+int md_util_is_dns_name(apr_pool_t *p, const char *hostname, int need_fqdn)
+{
+    char c, last = 0;
+    const char *cp = hostname;
+    int dots = 0;
+    
+    /* Since we use the names in certificates, we need pure ASCII domain names
+     * and IDN need to be converted to unicode. */
+    while ((c = *cp++)) {
+        switch (c) {
+            case '.':
+                if (last == '.') {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, p, "dns name with ..: %s", 
+                                  hostname);
+                    return 0;
+                }
+                ++dots;
+                break;
+            case '-':
+                break;
+            default:
+                if (!apr_isalnum(c)) {
+                    md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, p, "dns invalid char %c: %s", 
+                                  c, hostname);
+                    return 0;
+                }
+                break;
+        }
+        last = c;
+    }
+    
+    if (last == '.') { /* DNS names may end with '.' */
+        --dots;
+    }
+    if (need_fqdn && dots <= 0) { /* do not accept just top level domains */
+        md_log_perror(MD_LOG_MARK, MD_LOG_TRACE3, 0, p, "not a FQDN: %s", hostname);
+        return 0;
+    }
+    return 1; /* empty string not allowed */
+}
+
+const char *md_util_schemify(apr_pool_t *p, const char *s, const char *def_scheme)
+{
+    const char *cp = s;
+    while (*cp) {
+        if (*cp == ':') {
+            /* could be an url scheme, leave unchanged */
+            return s;
+        }
+        else if (!apr_isalnum(*cp)) {
+            break;
+        }
+        ++cp;
+    }
+    return apr_psprintf(p, "%s:%s", def_scheme, s);
+}
+
+apr_status_t md_util_abs_uri_check(apr_pool_t *p, const char *uri, const char **perr)
+{
+    const char *s, *err = NULL;
+    apr_uri_t uri_parsed;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS != (rv = apr_uri_parse(p, uri, &uri_parsed))) {
+        err = "not an uri";
+    }
+    else if (!uri_parsed.scheme) {
+        err = "missing uri scheme";
+    }
+    else if (strlen(uri_parsed.scheme) + 1 >= strlen(uri)) {
+        err = "missing uri identifier";
+    }
+    else if (strchr(uri, ' ') || strchr(uri, '\t') ) {
+        err = "whitespace in uri";
+    }
+    else if (!strncmp("http", uri_parsed.scheme, 4)) {
+        if (!uri_parsed.hostname) {
+            err = "missing hostname";
+        }
+        else if (!md_util_is_dns_name(p, uri_parsed.hostname, 0)) {
+            err = "invalid hostname";
+        }
+        if (uri_parsed.port_str && (uri_parsed.port == 0 || uri_parsed.port > 65353)) {
+            err = "invalid port";
+        }
+    }
+    else if (!strcmp("mailto", uri_parsed.scheme)) {
+        s = strchr(uri, '@');
+        if (!s) {
+            err = "missing @";
+        }
+        else if (strchr(s+1, '@')) {
+            err = "duplicate @";
+        }
+        else if (s == uri + strlen(uri_parsed.scheme) + 1) {
+            err = "missing local part";
+        }
+        else if (s == (uri + strlen(uri)-1)) {
+            err = "missing hostname";
+        }
+        else if (strstr(uri, "..")) {
+            err = "double period";
+        }
+    }
+    
+    if (err) {
+        rv = APR_EINVAL;
+    }
+    *perr = err;
+    return rv;
+}
+
+/* retry login ************************************************************************************/
+
+apr_status_t md_util_try(md_util_try_fn *fn, void *baton, int ignore_errs, 
+                         apr_interval_time_t timeout, apr_interval_time_t start_delay, 
+                         apr_interval_time_t max_delay, int backoff)
+{
+    apr_status_t rv;
+    apr_time_t now = apr_time_now();
+    apr_time_t giveup = now + timeout;
+    apr_interval_time_t nap_duration = start_delay? start_delay : apr_time_from_msec(100);
+    apr_interval_time_t nap_max = max_delay? max_delay : apr_time_from_sec(10);
+    apr_interval_time_t left;
+    int i = 0;
+    
+    while (1) {
+        if (APR_SUCCESS == (rv = fn(baton, i++))) {
+            break;
+        }
+        else if (!APR_STATUS_IS_EAGAIN(rv) && !ignore_errs) {
+            break;
+        }
+        
+        now = apr_time_now();
+        if (now > giveup) {
+            rv = APR_TIMEUP;
+            break;
+        }
+        
+        left = giveup - now;
+        if (nap_duration > left) {
+            nap_duration = left;
+        }
+        if (nap_duration > nap_max) {
+            nap_duration = nap_max;
+        }
+        
+        apr_sleep(nap_duration);
+        if (backoff) {
+            nap_duration *= 2;
+        } 
+    }
+    return rv;
+}
+
+/* base64 url encoding ****************************************************************************/
+
+static const int BASE64URL_UINT6[] = {
+/*   0   1   2   3   4   5   6   7   8   9   a   b   c   d   e   f        */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  0 */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  1 */ 
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, /*  2 */
+    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /*  3 */ 
+    -1, 0,  1,  2,  3,  4,  5,  6,   7,  8,  9, 10, 11, 12, 13, 14, /*  4 */
+    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, /*  5 */
+    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /*  6 */
+    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /*  7 */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  8 */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  9 */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  a */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  b */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  c */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  d */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*  e */
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1  /*  f */
+};
+static const char BASE64URL_CHARS[] = {
+    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', /*  0 -  9 */
+    'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', /* 10 - 19 */
+    'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', /* 20 - 29 */
+    'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', /* 30 - 39 */
+    'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', /* 40 - 49 */
+    'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', /* 50 - 59 */
+    '8', '9', '-', '_', ' ', ' ', ' ', ' ', ' ', ' ', /* 60 - 69 */
+};
+
+apr_size_t md_util_base64url_decode(const char **decoded, const char *encoded, 
+                                    apr_pool_t *pool)
+{
+    const unsigned char *e = (const unsigned char *)encoded;
+    const unsigned char *p = e;
+    unsigned char *d;
+    int n;
+    apr_size_t len, mlen, remain, i;
+    
+    while (*p && BASE64URL_UINT6[ *p ] != -1) {
+        ++p;
+    }
+    len = p - e;
+    mlen = (len/4)*4;
+    *decoded = apr_pcalloc(pool, len+1);
+    
+    i = 0;
+    d = (unsigned char*)*decoded;
+    for (; i < mlen; i += 4) {
+        n = ((BASE64URL_UINT6[ e[i+0] ] << 18) +
+             (BASE64URL_UINT6[ e[i+1] ] << 12) +
+             (BASE64URL_UINT6[ e[i+2] ] << 6) +
+             (BASE64URL_UINT6[ e[i+3] ]));
+        *d++ = n >> 16;
+        *d++ = n >> 8 & 0xffu;
+        *d++ = n & 0xffu;
+    }
+    remain = len - mlen;
+    switch (remain) {
+        case 2:
+            n = ((BASE64URL_UINT6[ e[mlen+0] ] << 18) +
+                 (BASE64URL_UINT6[ e[mlen+1] ] << 12));
+            *d++ = n >> 16;
+            remain = 1;
+            break;
+        case 3:
+            n = ((BASE64URL_UINT6[ e[mlen+0] ] << 18) +
+                 (BASE64URL_UINT6[ e[mlen+1] ] << 12) +
+                 (BASE64URL_UINT6[ e[mlen+2] ] << 6));
+            *d++ = n >> 16;
+            *d++ = n >> 8 & 0xffu;
+            remain = 2;
+            break;
+        default: /* do nothing */
+            break;
+    }
+    return mlen/4*3 + remain;
+}
+
+const char *md_util_base64url_encode(const char *data, 
+                                     apr_size_t dlen, apr_pool_t *pool)
+{
+    long i, len = (int)dlen;
+    apr_size_t slen = ((dlen+2)/3)*4 + 1; /* 0 terminated */
+    const unsigned char *udata = (const unsigned char*)data;
+    char *enc, *p = apr_pcalloc(pool, slen);
+    
+    enc = p;
+    for (i = 0; i < len-2; i+= 3) {
+        *p++ = BASE64URL_CHARS[ (udata[i] >> 2) & 0x3fu ];
+        *p++ = BASE64URL_CHARS[ ((udata[i] << 4) + (udata[i+1] >> 4)) & 0x3fu ];
+        *p++ = BASE64URL_CHARS[ ((udata[i+1] << 2) + (udata[i+2] >> 6)) & 0x3fu ];
+        *p++ = BASE64URL_CHARS[ udata[i+2] & 0x3fu ];
+    }
+    
+    if (i < len) {
+        *p++ = BASE64URL_CHARS[ (udata[i] >> 2) & 0x3fu ];
+        if (i == (len - 1)) {
+            *p++ = BASE64URL_CHARS[ (udata[i] << 4) & 0x3fu ];
+        }
+        else {
+            *p++ = BASE64URL_CHARS[ ((udata[i] << 4) + (udata[i+1] >> 4)) & 0x3fu ];
+            *p++ = BASE64URL_CHARS[ (udata[i+1] << 2) & 0x3fu ];
+        }
+    }
+    *p++ = '\0';
+    return enc;
+}
+
+/*******************************************************************************
+ * link header handling 
+ ******************************************************************************/
+
+typedef struct {
+    const char *s;
+    apr_size_t slen;
+    int i;
+    int link_start;
+    apr_size_t link_len;
+    int pn_start;
+    apr_size_t pn_len;
+    int pv_start;
+    apr_size_t pv_len;
+} link_ctx;
+
+static int attr_char(char c) 
+{
+    switch (c) {
+        case '!':
+        case '#':
+        case '$':
+        case '&':
+        case '+':
+        case '-':
+        case '.':
+        case '^':
+        case '_':
+        case '`':
+        case '|':
+        case '~':
+            return 1;
+        default:
+            return apr_isalnum(c);
+    }
+}
+
+static int ptoken_char(char c) 
+{
+    switch (c) {
+        case '!':
+        case '#':
+        case '$':
+        case '&':
+        case '\'':
+        case '(':
+        case ')':
+        case '*':
+        case '+':
+        case '-':
+        case '.':
+        case '/':
+        case ':':
+        case '<':
+        case '=':
+        case '>':
+        case '?':
+        case '@':
+        case '[':
+        case ']':
+        case '^':
+        case '_':
+        case '`':
+        case '{':
+        case '|':
+        case '}':
+        case '~':
+            return 1;
+        default:
+            return apr_isalnum(c);
+    }
+}
+
+static int skip_ws(link_ctx *ctx)
+{
+    char c;
+    while (ctx->i < ctx->slen 
+           && (((c = ctx->s[ctx->i]) == ' ') || (c == '\t'))) {
+        ++ctx->i;
+    }
+    return (ctx->i < ctx->slen);
+}
+
+static int skip_nonws(link_ctx *ctx)
+{
+    char c;
+    while (ctx->i < ctx->slen 
+           && (((c = ctx->s[ctx->i]) != ' ') && (c != '\t'))) {
+        ++ctx->i;
+    }
+    return (ctx->i < ctx->slen);
+}
+
+static int find_chr(link_ctx *ctx, char c, int *pidx)
+{
+    int j;
+    for (j = ctx->i; j < ctx->slen; ++j) {
+        if (ctx->s[j] == c) {
+            *pidx = j;
+            return 1;
+        }
+    } 
+    return 0;
+}
+
+static int read_chr(link_ctx *ctx, char c)
+{
+    if (ctx->i < ctx->slen && ctx->s[ctx->i] == c) {
+        ++ctx->i;
+        return 1;
+    }
+    return 0;
+}
+
+static int skip_qstring(link_ctx *ctx)
+{
+    if (skip_ws(ctx) && read_chr(ctx, '\"')) {
+        int end;
+        if (find_chr(ctx, '\"', &end)) {
+            ctx->i = end + 1;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static int skip_ptoken(link_ctx *ctx)
+{
+    if (skip_ws(ctx)) {
+        int i;
+        for (i = ctx->i; i < ctx->slen && ptoken_char(ctx->s[i]); ++i) {
+            /* nop */
+        }
+        if (i > ctx->i) {
+            ctx->i = i;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+
+static int read_link(link_ctx *ctx)
+{
+    ctx->link_start = ctx->link_len = 0;
+    if (skip_ws(ctx) && read_chr(ctx, '<')) {
+        int end;
+        if (find_chr(ctx, '>', &end)) {
+            ctx->link_start = ctx->i;
+            ctx->link_len = end - ctx->link_start;
+            ctx->i = end + 1;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static int skip_pname(link_ctx *ctx)
+{
+    if (skip_ws(ctx)) {
+        int i;
+        for (i = ctx->i; i < ctx->slen && attr_char(ctx->s[i]); ++i) {
+            /* nop */
+        }
+        if (i > ctx->i) {
+            ctx->i = i;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static int skip_pvalue(link_ctx *ctx)
+{
+    if (skip_ws(ctx) && read_chr(ctx, '=')) {
+        ctx->pv_start = ctx->i;
+        if (skip_qstring(ctx) || skip_ptoken(ctx)) {
+            ctx->pv_len = ctx->i - ctx->pv_start;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static int skip_param(link_ctx *ctx)
+{
+    if (skip_ws(ctx) && read_chr(ctx, ';')) {
+        ctx->pn_start = ctx->i;
+        ctx->pn_len = 0;
+        if (skip_pname(ctx)) {
+            ctx->pn_len = ctx->i - ctx->pn_start;
+            ctx->pv_len = 0;
+            skip_pvalue(ctx); /* value is optional */
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static int pv_contains(link_ctx *ctx, const char *s)
+{
+    int pvstart = ctx->pv_start;
+    apr_size_t pvlen = ctx->pv_len;
+    
+    if (ctx->s[pvstart] == '\"' && pvlen > 1) {
+        ++pvstart;
+        pvlen -= 2;
+    }
+    if (pvlen > 0) {
+        apr_size_t slen = strlen(s);
+        link_ctx pvctx;
+        int i;
+        
+        memset(&pvctx, 0, sizeof(pvctx));
+        pvctx.s = ctx->s + pvstart;
+        pvctx.slen = pvlen;
+
+        for (i = 0; i < pvctx.slen; i = pvctx.i) {
+            skip_nonws(&pvctx);
+            if ((pvctx.i - i) == slen && !strncmp(s, pvctx.s + i, slen)) {
+                return 1;
+            }
+            skip_ws(&pvctx);
+        }
+    }
+    return 0;
+}
+
+/* RFC 5988 <https://tools.ietf.org/html/rfc5988#section-6.2.1>
+  Link           = "Link" ":" #link-value
+  link-value     = "<" URI-Reference ">" *( ";" link-param )
+  link-param     = ( ( "rel" "=" relation-types )
+                 | ( "anchor" "=" <"> URI-Reference <"> )
+                 | ( "rev" "=" relation-types )
+                 | ( "hreflang" "=" Language-Tag )
+                 | ( "media" "=" ( MediaDesc | ( <"> MediaDesc <"> ) ) )
+                 | ( "title" "=" quoted-string )
+                 | ( "title*" "=" ext-value )
+                 | ( "type" "=" ( media-type | quoted-mt ) )
+                 | ( link-extension ) )
+  link-extension = ( parmname [ "=" ( ptoken | quoted-string ) ] )
+                 | ( ext-name-star "=" ext-value )
+  ext-name-star  = parmname "*" ; reserved for RFC2231-profiled
+                                ; extensions.  Whitespace NOT
+                                ; allowed in between.
+  ptoken         = 1*ptokenchar
+  ptokenchar     = "!" | "#" | "$" | "%" | "&" | "'" | "("
+                 | ")" | "*" | "+" | "-" | "." | "/" | DIGIT
+                 | ":" | "<" | "=" | ">" | "?" | "@" | ALPHA
+                 | "[" | "]" | "^" | "_" | "`" | "{" | "|"
+                 | "}" | "~"
+  media-type     = type-name "/" subtype-name
+  quoted-mt      = <"> media-type <">
+  relation-types = relation-type
+                 | <"> relation-type *( 1*SP relation-type ) <">
+  relation-type  = reg-rel-type | ext-rel-type
+  reg-rel-type   = LOALPHA *( LOALPHA | DIGIT | "." | "-" )
+  ext-rel-type   = URI
+  
+  and from <https://tools.ietf.org/html/rfc5987>
+  parmname      = 1*attr-char
+  attr-char     = ALPHA / DIGIT
+                   / "!" / "#" / "$" / "&" / "+" / "-" / "."
+                   / "^" / "_" / "`" / "|" / "~"
+ */
+
+typedef struct {
+    apr_pool_t *pool;
+    const char *relation;
+    const char *url;
+} find_ctx;
+
+static int find_url(void *baton, const char *key, const char *value)
+{
+    find_ctx *outer = baton;
+    
+    if (!apr_strnatcasecmp("link", key)) {
+        link_ctx ctx;
+        
+        memset(&ctx, 0, sizeof(ctx));
+        ctx.s = value;
+        ctx.slen = (int)strlen(value);
+        
+        while (read_link(&ctx)) {
+            while (skip_param(&ctx)) {
+                if (ctx.pn_len == 3 && !strncmp("rel", ctx.s + ctx.pn_start, 3)
+                    && pv_contains(&ctx, outer->relation)) {
+                    /* this is the link relation we are looking for */
+                    outer->url = apr_pstrndup(outer->pool, ctx.s + ctx.link_start, ctx.link_len);
+                    return 0;
+                }
+            }
+        }
+    }
+    return 1;
+}
+
+const char *md_link_find_relation(const apr_table_t *headers, 
+                                  apr_pool_t *pool, const char *relation)
+{
+    find_ctx ctx;
+    
+    memset(&ctx, 0, sizeof(ctx));
+    ctx.pool = pool;
+    ctx.relation = relation;
+    
+    apr_table_do(find_url, &ctx, headers, NULL);
+    
+    return ctx.url;
+}
+
diff --git a/modules/md/md_util.h b/modules/md/md_util.h
new file mode 100644
index 0000000000..02c72bcf02
--- /dev/null
+++ b/modules/md/md_util.h
@@ -0,0 +1,133 @@
+/* Copyright 2017 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef mod_md_md_util_h
+#define mod_md_md_util_h
+
+#include <stdio.h>
+#include <apr_file_io.h>
+
+struct apr_array_header_t;
+struct apr_table_t;
+
+/**************************************************************************************************/
+/* pool utils */
+
+typedef apr_status_t md_util_action(void *baton, apr_pool_t *p, apr_pool_t *ptemp);
+typedef apr_status_t md_util_vaction(void *baton, apr_pool_t *p, apr_pool_t *ptemp, va_list ap);
+
+apr_status_t md_util_pool_do(md_util_action *cb, void *baton, apr_pool_t *p); 
+apr_status_t md_util_pool_vdo(md_util_vaction *cb, void *baton, apr_pool_t *p, ...); 
+
+/**************************************************************************************************/
+/* string related */
+char *md_util_str_tolower(char *s);
+
+int md_array_str_index(const struct apr_array_header_t *array, const char *s, 
+                       int start, int case_sensitive);
+
+int md_array_str_eq(const struct apr_array_header_t *a1, 
+                    const struct apr_array_header_t *a2, int case_sensitive);
+
+struct apr_array_header_t *md_array_str_clone(apr_pool_t *p, struct apr_array_header_t *array);
+
+struct apr_array_header_t *md_array_str_compact(apr_pool_t *p, struct apr_array_header_t *src,
+                                                int case_sensitive);
+
+struct apr_array_header_t *md_array_str_remove(apr_pool_t *p, struct apr_array_header_t *src, 
+                                               const char *exclude, int case_sensitive);
+
+int md_array_str_add_missing(struct apr_array_header_t *dest, 
+                             struct apr_array_header_t *src, int case_sensitive);
+
+/**************************************************************************************************/
+/* dns name check */
+
+int md_util_is_dns_name(apr_pool_t *p, const char *hostname, int need_fqdn);
+
+/**************************************************************************************************/
+/* file system related */
+
+struct apr_file_t;
+struct apr_finfo_t;
+
+apr_status_t md_util_fopen(FILE **pf, const char *fn, const char *mode);
+
+apr_status_t md_util_fcreatex(struct apr_file_t **pf, const char *fn, 
+                              apr_fileperms_t perms, apr_pool_t *p);
+
+apr_status_t md_util_path_merge(const char **ppath, apr_pool_t *p, ...);
+
+apr_status_t md_util_is_dir(const char *path, apr_pool_t *pool);
+apr_status_t md_util_is_file(const char *path, apr_pool_t *pool);
+
+typedef apr_status_t md_util_file_cb(void *baton, struct apr_file_t *f, apr_pool_t *p);
+
+apr_status_t md_util_freplace(const char *fpath, apr_fileperms_t perms, apr_pool_t *p, 
+                              md_util_file_cb *write, void *baton);
+
+/** 
+ * Remove a file/directory and all files/directories contain up to max_level. If max_level == 0,
+ * only an empty directory or a file can be removed.
+ */
+apr_status_t md_util_rm_recursive(const char *fpath, apr_pool_t *p, int max_level);
+
+typedef apr_status_t md_util_fdo_cb(void *baton, apr_pool_t *p, apr_pool_t *ptemp, 
+                                         const char *dir, const char *name, 
+                                         apr_filetype_e ftype);
+                                         
+apr_status_t md_util_files_do(md_util_fdo_cb *cb, void *baton, apr_pool_t *p, 
+                              const char *path, ...);
+
+/**
+ * Depth first traversal of directory tree starting at path.
+ */
+apr_status_t md_util_tree_do(md_util_fdo_cb *cb, void *baton, apr_pool_t *p, 
+                             const char *path, int follow_links);
+
+apr_status_t md_util_ftree_remove(const char *path, apr_pool_t *p);
+
+apr_status_t md_text_fread8k(const char **ptext, apr_pool_t *p, const char *fpath);
+apr_status_t md_text_fcreatex(const char *fpath, apr_fileperms_t 
+                              perms, apr_pool_t *p, const char *text);
+apr_status_t md_text_freplace(const char *fpath, apr_fileperms_t perms, 
+                              apr_pool_t *p, const char *text); 
+
+/**************************************************************************************************/
+/* base64 url encodings */
+const char *md_util_base64url_encode(const char *data, 
+                                     apr_size_t len, apr_pool_t *pool);
+apr_size_t md_util_base64url_decode(const char **decoded, const char *encoded, 
+                                    apr_pool_t *pool);
+
+/**************************************************************************************************/
+/* http/url related */
+const char *md_util_schemify(apr_pool_t *p, const char *s, const char *def_scheme);
+
+apr_status_t md_util_abs_uri_check(apr_pool_t *p, const char *s, const char **perr);
+ 
+const char *md_link_find_relation(const struct apr_table_t *headers, 
+                                  apr_pool_t *pool, const char *relation);
+
+/**************************************************************************************************/
+/* retry logic */
+
+typedef apr_status_t md_util_try_fn(void *baton, int i);
+
+apr_status_t md_util_try(md_util_try_fn *fn, void *baton, int ignore_errs,  
+                         apr_interval_time_t timeout, apr_interval_time_t start_delay, 
+                         apr_interval_time_t max_delay, int backoff);
+
+#endif /* md_util_h */
diff --git a/modules/md/md_version.h b/modules/md/md_version.h
new file mode 100644
index 0000000000..60afe0f809
--- /dev/null
+++ b/modules/md/md_version.h
@@ -0,0 +1,42 @@
+/* Copyright 2015 greenbytes GmbH (https://www.greenbytes.de)
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+#ifndef mod_md_md_version_h
+#define mod_md_md_version_h
+
+#undef PACKAGE_VERSION
+#undef PACKAGE_TARNAME
+#undef PACKAGE_STRING
+#undef PACKAGE_NAME
+#undef PACKAGE_BUGREPORT
+
+/**
+ * @macro
+ * Version number of the md module as c string
+ */
+#define MOD_MD_VERSION "0.5.0-git"
+
+/**
+ * @macro
+ * Numerical representation of the version number of the md module
+ * release. This is a 24 bit number with 8 bits for major number, 8 bits
+ * for minor and 8 bits for patch. Version 1.2.3 becomes 0x010203.
+ */
+#define MOD_MD_VERSION_NUM 0x000500
+
+#define MD_EXPERIMENTAL 1
+#define MD_ACME_DEF_URL    "https://acme-staging.api.letsencrypt.org/directory"
+
+#endif /* mod_md_md_version_h */
diff --git a/modules/md/mod_md.c b/modules/md/mod_md.c
new file mode 100644
index 0000000000..691f2fcdea
--- /dev/null
+++ b/modules/md/mod_md.c
@@ -0,0 +1,970 @@
+/* Copyright 2015 greenbytes GmbH (https://www.greenbytes.de)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <apr_strings.h>
+
+#include <ap_release.h>
+#include <mpm_common.h>
+#include <httpd.h>
+#include <http_protocol.h>
+#include <http_request.h>
+#include <http_log.h>
+#include <http_vhost.h>
+#include <ap_listen.h>
+
+#include "md.h"
+#include "mod_md.h"
+#include "md_config.h"
+#include "md_curl.h"
+#include "md_crypt.h"
+#include "md_http.h"
+#include "md_store.h"
+#include "md_store_fs.h"
+#include "md_log.h"
+#include "md_reg.h"
+#include "md_util.h"
+#include "md_version.h"
+#include "md_acme.h"
+#include "md_acme_authz.h"
+
+#include "md_os.h"
+#include "mod_watchdog.h"
+
+static void md_hooks(apr_pool_t *pool);
+
+AP_DECLARE_MODULE(md) = {
+    STANDARD20_MODULE_STUFF,
+    md_config_create_dir, /* func to create per dir config */
+    md_config_merge_dir,  /* func to merge per dir config */
+    md_config_create_svr, /* func to create per server config */
+    md_config_merge_svr,  /* func to merge per server config */
+    md_cmds,              /* command handlers */
+    md_hooks
+};
+
+typedef struct {
+    apr_array_header_t *mds;
+    apr_array_header_t *unused_names;
+    int can_http;
+    int can_https;
+} md_ctx;
+ 
+static apr_status_t md_calc_md_list(md_ctx *ctx, apr_pool_t *p, apr_pool_t *plog,
+                                    apr_pool_t *ptemp, server_rec *base_server)
+{
+    server_rec *s;
+    apr_array_header_t *mds;
+    int i, j;
+    md_t *md, *nmd;
+    const char *domain;
+    apr_status_t rv = APR_SUCCESS;
+    md_config_t *config;
+    apr_port_t effective_80, effective_443;
+    ap_listen_rec *lr;
+    apr_sockaddr_t *sa;
+
+    ctx->can_http = 0;
+    ctx->can_https = 0;
+    mds = apr_array_make(p, 5, sizeof(const md_t*));
+
+    config = (md_config_t *)md_config_get(base_server);
+    effective_80 = md_config_geti(config, MD_CONFIG_LOCAL_80);
+    effective_443 = md_config_geti(config, MD_CONFIG_LOCAL_443);
+    
+    for (lr = ap_listeners; lr; lr = lr->next) {
+        for (sa = lr->bind_addr; sa; sa = sa->next) {
+            if  (sa->port == effective_80 
+                 && (!lr->protocol || !strncmp("http", lr->protocol, 4))) {
+                ctx->can_http = 1;
+            }
+            else if (sa->port == effective_443
+                     && (!lr->protocol || !strncmp("http", lr->protocol, 4))) {
+                ctx->can_https = 1;
+            }
+        }
+    }
+    
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, base_server, APLOGNO()
+                 "server seems%s reachable via http: (port 80->%d) "
+                 "and%s reachable via https: (port 443->%d) ",
+                 ctx->can_http? "" : " not", effective_80,
+                 ctx->can_https? "" : " not", effective_443);
+    
+    for (s = base_server; s; s = s->next) {
+        config = (md_config_t *)md_config_get(s);
+
+        for (i = 0; i < config->mds->nelts; ++i) {
+            nmd = APR_ARRAY_IDX(config->mds, i, md_t*);
+
+            for (j = 0; j < mds->nelts; ++j) {
+                md = APR_ARRAY_IDX(mds, j, md_t*);
+
+                if (nmd == md) {
+                    nmd = NULL;
+                    break; /* merged between different configs */
+                }
+                
+                if ((domain = md_common_name(nmd, md)) != NULL) {
+                    ap_log_error(APLOG_MARK, APLOG_ERR, 0, base_server, APLOGNO()
+                                 "two Managed Domains have an overlap in domain '%s'"
+                                 ", first definition in %s(line %d), second in %s(line %d)",
+                                 domain, md->defn_name, md->defn_line_number,
+                                 nmd->defn_name, nmd->defn_line_number);
+                    return APR_EINVAL;
+                }
+            }
+            
+            if (nmd) {
+                /* new managed domain not seen before */
+                if (!nmd->ca_url) {
+                    nmd->ca_url = md_config_gets(config, MD_CONFIG_CA_URL);
+                }
+                if (!nmd->ca_proto) {
+                    nmd->ca_proto = md_config_gets(config, MD_CONFIG_CA_PROTO);
+                }
+                if (!nmd->ca_agreement) {
+                    nmd->ca_agreement = md_config_gets(config, MD_CONFIG_CA_AGREEMENT);
+                }
+                if (s->server_admin && strcmp(DEFAULT_ADMIN, s->server_admin)) {
+                    apr_array_clear(nmd->contacts);
+                    APR_ARRAY_PUSH(nmd->contacts, const char *) = 
+                        md_util_schemify(p, s->server_admin, "mailto");
+                }
+                if (nmd->drive_mode == MD_DRIVE_DEFAULT) {
+                    nmd->drive_mode = md_config_geti(config, MD_CONFIG_DRIVE_MODE);
+                }
+                if (nmd->renew_window <= 0) {
+                    nmd->renew_window = md_config_get_interval(config, MD_CONFIG_RENEW_WINDOW);
+                }
+                if (!nmd->ca_challenges && config->ca_challenges) {
+                    nmd->ca_challenges = apr_array_copy(p, config->ca_challenges);
+                }
+                APR_ARRAY_PUSH(mds, md_t *) = nmd;
+                
+                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, base_server, APLOGNO()
+                             "Added MD[%s, CA=%s, Proto=%s, Agreement=%s, Drive=%d, renew=%ld]",
+                             nmd->name, nmd->ca_url, nmd->ca_proto, nmd->ca_agreement,
+                             nmd->drive_mode, (long)nmd->renew_window);
+            }
+        }
+    }
+    ctx->mds = (APR_SUCCESS == rv)? mds : NULL;
+    return rv;
+}
+
+static apr_status_t md_check_vhost_mapping(md_ctx *ctx, apr_pool_t *p, apr_pool_t *plog,
+                                           apr_pool_t *ptemp, server_rec *base_server)
+{
+    server_rec *s;
+    request_rec r;
+    md_config_t *config;
+    apr_status_t rv = APR_SUCCESS;
+    md_t *md;
+    int i, j, k;
+    const char *domain, *name;
+    
+    /* Find the (at most one) managed domain for each vhost/base server and
+     * remember it at our config for it. 
+     * The config is not accepted, if a vhost matches 2 or more managed domains.
+     */
+    ctx->unused_names = apr_array_make(p, 5, sizeof(const char*));
+    memset(&r, 0, sizeof(r));
+    for (i = 0; i < ctx->mds->nelts; ++i) {
+        md = APR_ARRAY_IDX(ctx->mds, i, md_t*);
+        config = NULL;
+        /* This MD may apply to 0, 1 or more sever_recs */
+        for (s = base_server; s; s = s->next) {
+            r.server = s;
+            for (j = 0; j < md->domains->nelts; ++j) {
+                domain = APR_ARRAY_IDX(md->domains, j, const char*);
+                
+                if (ap_matches_request_vhost(&r, domain, s->port)) {
+                    /* Create a unique md_config_t record for this server. 
+                     * We keep local information here. */
+                    config = (md_config_t *)md_config_get_unique(s, p);
+                
+                    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, base_server, APLOGNO()
+                                 "Server %s:%d matches md %s (config %s)", 
+                                 s->server_hostname, s->port, md->name, config->name);
+                    
+                    if (config->md == md) {
+                        /* already matched via another domain name */
+                    }
+                    else if (config->md) {
+                         
+                        ap_log_error(APLOG_MARK, APLOG_ERR, 0, base_server, APLOGNO()
+                                     "conflict: MD %s matches server %s, but MD %s also matches.",
+                                     md->name, s->server_hostname, config->md->name);
+                        rv = APR_EINVAL;
+                        goto next_server;
+                    }
+                    
+                    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, base_server, APLOGNO()
+                                 "Managed Domain %s applies to vhost %s:%d", md->name,
+                                 s->server_hostname, s->port);
+                    if (s->server_admin && strcmp(DEFAULT_ADMIN, s->server_admin)) {
+                        apr_array_clear(md->contacts);
+                        APR_ARRAY_PUSH(md->contacts, const char *) = 
+                            md_util_schemify(p, s->server_admin, "mailto");
+                        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, base_server, APLOGNO()
+                                     "Managed Domain %s assigned server admin %s", md->name,
+                                     s->server_admin);
+                    }
+                    config->md = md;
+
+                    /* This server matches a managed domain. If it contains names or
+                     * alias that are not in this md, a generated certificate will not match. */
+                    if (!md_contains(md, s->server_hostname)) {
+                        ap_log_error(APLOG_MARK, APLOG_ERR, 0, base_server, APLOGNO()
+                                     "Virtual Host %s:%d matches Managed Domain '%s', but the name"
+                                     " itself is not managed. A requested MD certificate will "
+                                     "not match ServerName.",
+                                     s->server_hostname, s->port, md->name);
+                        rv = APR_EINVAL;
+                        goto next_server;
+                    }
+                    else {
+                        for (k = 0; k < s->names->nelts; ++k) {
+                            name = APR_ARRAY_IDX(s->names, k, const char*);
+                            if (!md_contains(md, name)) {
+                                ap_log_error(APLOG_MARK, APLOG_ERR, 0, base_server, APLOGNO()
+                                             "Virtual Host %s:%d matches Managed Domain '%s', but "
+                                             "the ServerAlias %s is not covered by the MD. "
+                                             "A requested MD certificate will not match this " 
+                                             "alias.", s->server_hostname, s->port, md->name,
+                                             name);
+                                rv = APR_EINVAL;
+                                goto next_server;
+                            }
+                        }
+                    }
+                    goto next_server;
+                }
+            }
+next_server:
+            continue;
+        }
+        
+        if (config == NULL && md->drive_mode != MD_DRIVE_ALWAYS) {
+            /* Not an error, but looks suspicious */
+            ap_log_error(APLOG_MARK, APLOG_WARNING, 0, base_server, APLOGNO()
+                         "No VirtualHost matches Managed Domain %s", md->name);
+            APR_ARRAY_PUSH(ctx->unused_names, const char*)  = md->name;
+        }
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* store & registry setup */
+
+static apr_status_t store_file_ev(void *baton, struct md_store_t *store,
+                                    md_store_fs_ev_t ev, int group, 
+                                    const char *fname, apr_filetype_e ftype,  
+                                    apr_pool_t *p)
+{
+    server_rec *s = baton;
+    apr_status_t rv;
+    
+    ap_log_error(APLOG_MARK, APLOG_TRACE3, 0, s, "store event=%d on %s %s (group %d)", 
+                 ev, (ftype == APR_DIR)? "dir" : "file", fname, group);
+                 
+    /* Directories in group CHALLENGES and STAGING are written to by our watchdog,
+     * running on certain mpms in a child process under a different user. Give them
+     * ownership. 
+     */
+    if (ftype == APR_DIR) {
+        switch (group) {
+            case MD_SG_CHALLENGES:
+            case MD_SG_STAGING:
+                rv = md_make_worker_accessible(fname, p);
+                if (APR_ENOTIMPL != rv) {
+                    return rv;
+                }
+                break;
+            default: 
+                break;
+        }
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t check_group_dir(md_store_t *store, md_store_group_t group, 
+                                    apr_pool_t *p, server_rec *s)
+{
+    const char *dir;
+    apr_status_t rv;
+    
+    if (APR_SUCCESS == (rv = md_store_get_fname(&dir, store, group, NULL, NULL, p))
+        && APR_SUCCESS == (rv = apr_dir_make_recursive(dir, MD_FPROT_D_UALL_GREAD, p))) {
+        rv = store_file_ev(s, store, MD_S_FS_EV_CREATED, group, dir, APR_DIR, p);
+    }
+    return rv;
+}
+
+static apr_status_t setup_store(md_store_t **pstore, apr_pool_t *p, server_rec *s,
+                                int post_config)
+{
+    const char *base_dir;
+    md_config_t *config;
+    md_store_t *store;
+    apr_status_t rv;
+    
+    config = (md_config_t *)md_config_get(s);
+    base_dir = md_config_gets(config, MD_CONFIG_BASE_DIR);
+    base_dir = ap_server_root_relative(p, base_dir);
+    
+    if (APR_SUCCESS != (rv = md_store_fs_init(&store, p, base_dir))) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO()"setup store for %s", base_dir);
+        goto out;
+    }
+
+    if (post_config) {
+        md_store_fs_set_event_cb(store, store_file_ev, s);
+        if (APR_SUCCESS != (rv = check_group_dir(store, MD_SG_CHALLENGES, p, s))) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO() 
+                         "setup challenges directory");
+            goto out;
+        }
+        if (APR_SUCCESS != (rv = check_group_dir(store, MD_SG_STAGING, p, s))) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO() 
+                         "setup staging directory");
+            goto out;
+        }
+        if (APR_SUCCESS != (rv = check_group_dir(store, MD_SG_ACCOUNTS, p, s))) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO() 
+                         "setup accounts directory");
+            goto out;
+        }
+        
+    }
+    
+    config->store = store;
+    for (s = s->next; s; s = s->next) {
+        config = (md_config_t *)md_config_get(s);
+        config->store = store;
+    }
+out:
+    *pstore = (APR_SUCCESS == rv)? store : NULL;
+    return rv;
+}
+
+static apr_status_t setup_reg(md_reg_t **preg, apr_pool_t *p, server_rec *s, int post_config)
+{
+    md_config_t *config;
+    apr_status_t rv;
+    
+    config = (md_config_t *)md_config_get(s);
+    if (config->store 
+        || APR_SUCCESS == (rv = setup_store(&config->store, p, s, post_config))) {
+        return md_reg_init(preg, p, config->store);
+    }
+    return rv;
+}
+
+/**************************************************************************************************/
+/* logging setup */
+
+static server_rec *log_server;
+
+static int log_is_level(void *baton, apr_pool_t *p, md_log_level_t level)
+{
+    if (log_server) {
+        return APLOG_IS_LEVEL(log_server, level);
+    }
+    return level <= MD_LOG_INFO;
+}
+
+#define LOG_BUF_LEN 16*1024
+
+static void log_print(const char *file, int line, md_log_level_t level, 
+                      apr_status_t rv, void *baton, apr_pool_t *p, const char *fmt, va_list ap)
+{
+    if (log_is_level(baton, p, level)) {
+        char buffer[LOG_BUF_LEN];
+        
+        memset(buffer, 0, sizeof(buffer));
+        apr_vsnprintf(buffer, LOG_BUF_LEN-1, fmt, ap);
+        buffer[LOG_BUF_LEN-1] = '\0';
+
+        if (log_server) {
+            ap_log_error(file, line, APLOG_MODULE_INDEX, level, rv, log_server, "%s",buffer);
+        }
+        else {
+            ap_log_perror(file, line, APLOG_MODULE_INDEX, level, rv, p, "%s", buffer);
+        }
+    }
+}
+
+/**************************************************************************************************/
+/* lifecycle */
+
+static apr_status_t cleanup_setups(void *dummy)
+{
+    (void)dummy;
+    log_server = NULL;
+    return APR_SUCCESS;
+}
+
+static void init_setups(apr_pool_t *p, server_rec *base_server) 
+{
+    log_server = base_server;
+    apr_pool_cleanup_register(p, NULL, cleanup_setups, apr_pool_cleanup_null);
+}
+
+/**************************************************************************************************/
+/* watchdog based impl. */
+
+#define MD_WATCHDOG_NAME   "_md_"
+
+static APR_OPTIONAL_FN_TYPE(ap_watchdog_get_instance) *wd_get_instance;
+static APR_OPTIONAL_FN_TYPE(ap_watchdog_register_callback) *wd_register_callback;
+static APR_OPTIONAL_FN_TYPE(ap_watchdog_set_callback_interval) *wd_set_interval;
+
+typedef struct {
+    apr_pool_t *p;
+    server_rec *s;
+    ap_watchdog_t *watchdog;
+    int all_valid;
+    int error_count;
+    int processed_count;
+
+    int error_runs;
+    apr_time_t next_change;
+    
+    apr_array_header_t *mds;
+    md_reg_t *reg;
+} md_watchdog;
+
+static apr_status_t drive_md(md_watchdog *wd, md_t *md, apr_pool_t *ptemp)
+{
+    apr_status_t rv = APR_SUCCESS;
+    apr_time_t renew_time;
+    int errored, renew;
+    char ts[APR_RFC822_DATE_LEN];
+    
+    if (APR_SUCCESS == (rv = md_reg_assess(wd->reg, md, &errored, &renew, wd->p))) {
+        if (errored) {
+            ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO() 
+                         "md(%s): in error state", md->name);
+        }
+        else if (md->state == MD_S_COMPLETE && !md->expires) {
+            /* This is our indicator that we did already renew this managed domain
+             * successfully and only wait on the next restart for it to activate */
+            ap_log_error( APLOG_MARK, APLOG_INFO, 0, wd->s, APLOGNO() 
+                         "md(%s): has been renewed, will activate on next restart", md->name);
+        }
+        else if (renew) {
+            ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO() 
+                         "md(%s): state=%d, driving", md->name, md->state);
+            rv = md_reg_stage(wd->reg, md, NULL, 0, ptemp);
+            if (APR_SUCCESS == rv) {
+                md->state = MD_S_COMPLETE;
+                md->expires = 0;
+                ++wd->processed_count;
+            }
+        }
+        else {
+            apr_rfc822_date(ts, md->expires);
+            ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO() 
+                         "md(%s): is complete, cert expires %s", md->name, ts);
+            renew_time = md->expires - md->renew_window;
+            if (renew_time < wd->next_change) {
+                wd->next_change = renew_time;
+            }
+        }
+    }
+    return rv;
+}
+
+static apr_status_t run_watchdog(int state, void *baton, apr_pool_t *ptemp)
+{
+    md_watchdog *wd = baton;
+    apr_status_t rv = APR_SUCCESS;
+    md_t *md;
+    apr_interval_time_t interval;
+    int i;
+    
+    switch (state) {
+        case AP_WATCHDOG_STATE_STARTING:
+            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO()
+                         "md watchdog start, auto drive %d mds", wd->mds->nelts);
+            break;
+        case AP_WATCHDOG_STATE_RUNNING:
+            assert(wd->reg);
+            
+            /* normally, we'd like to run at least twice a day */
+            interval = apr_time_from_sec(MD_SECS_PER_DAY / 2);
+
+            wd->all_valid = 1;
+            wd->processed_count = 0;
+            wd->error_count = 0;
+            wd->next_change = 0;
+            
+            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO()
+                         "md watchdog run, auto drive %d mds", wd->mds->nelts);
+                         
+            /* Check if all Managed Domains are ok or if we have to do something */
+            for (i = 0; i < wd->mds->nelts; ++i) {
+                md = APR_ARRAY_IDX(wd->mds, i, md_t *);
+                if (APR_SUCCESS != (rv = drive_md(wd, md, ptemp))) {
+                    wd->all_valid = 0;
+                    ++wd->error_count;
+                    ap_log_error( APLOG_MARK, APLOG_ERR, rv, wd->s, APLOGNO() 
+                                 "processing %s", md->name);
+                }
+            }
+
+            /* Determine when we want to run next */
+            wd->error_runs = wd->error_count? (wd->error_runs + 1) : 0;
+            if (wd->all_valid) {
+                ap_log_error( APLOG_MARK, APLOG_TRACE1, 0, wd->s, "all managed domains are valid");
+            }
+            else {
+                /* back off duration, depending on the errors we encounter in a row */
+                interval = apr_time_from_sec(5 << (wd->error_runs - 1));
+                if (interval > apr_time_from_sec(60*60)) {
+                    interval = apr_time_from_sec(60*60);
+                }
+                ap_log_error( APLOG_MARK, APLOG_INFO, 0, wd->s, APLOGNO() 
+                             "encountered errors for the %d. time, next run in %d seconds",
+                             wd->error_runs, (int)apr_time_sec(interval));
+            }
+            
+            /* We follow the chosen min_interval for re-evaluation, unless we
+             * know of a change (renewal) that happens before that. */
+            if (wd->next_change) {
+                apr_interval_time_t until_next = wd->next_change - apr_time_now();
+                if (until_next < interval) {
+                    interval = until_next;
+                }
+            }
+            
+            /* Set when we'd like to be run next time. 
+             * TODO: it seems that this is really only ticking down when the server
+             * runs. When you wake up a hibernated machine, the watchdog will not run right away 
+             */
+            if (APLOGdebug(wd->s)) {
+                int secs = (int)(apr_time_sec(interval) % MD_SECS_PER_DAY);
+                ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, wd->s, "next run in %2d:%02d:%02d hours", 
+                             (int)secs/MD_SECS_PER_HOUR, (int)(secs%(MD_SECS_PER_HOUR))/60,
+                             (int)(secs%60));
+            }
+            wd_set_interval(wd->watchdog, interval, wd, run_watchdog);
+            break;
+        case AP_WATCHDOG_STATE_STOPPING:
+            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO()
+                         "md watchdog stopping");
+            break;
+    }
+
+    if (wd->processed_count) {
+        if (wd->all_valid) {
+            rv = md_server_graceful(ptemp, wd->s);
+            if (APR_ENOTIMPL == rv) {
+                /* self-graceful restart not supported in this setup */
+                ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, wd->s, APLOGNO()
+                             "%d Managed Domain%s been setup and changes will be "
+                             "activated on next (graceful) server restart.",
+                             wd->processed_count, (wd->processed_count > 1)? "s have" : " has");
+            }
+        }
+        else {
+            ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, wd->s, APLOGNO()
+                         "%d Managed Domain%s been setup, while %d%s "
+                         "still being worked on. You may activate the changes made "
+                         "by triggering a (graceful) restart at any time.",
+                         wd->processed_count, (wd->processed_count > 1)? "s have" : " has",
+                         wd->error_count, (wd->error_count > 1)? " are" : " is");
+        }
+    }
+    
+    return APR_SUCCESS;
+}
+
+static apr_status_t start_watchdog(apr_array_header_t *names, apr_pool_t *p, 
+                                   md_reg_t *reg, server_rec *s)
+{
+    apr_allocator_t *allocator;
+    md_watchdog *wd;
+    apr_pool_t *wdp;
+    apr_status_t rv;
+    const char *name;
+    md_t *md;
+    int i, errored, renew;
+    
+    wd_get_instance = APR_RETRIEVE_OPTIONAL_FN(ap_watchdog_get_instance);
+    wd_register_callback = APR_RETRIEVE_OPTIONAL_FN(ap_watchdog_register_callback);
+    wd_set_interval = APR_RETRIEVE_OPTIONAL_FN(ap_watchdog_set_callback_interval);
+    
+    if (!wd_get_instance || !wd_register_callback || !wd_set_interval) {
+        ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO() "mod_watchdog is required");
+        return !OK;
+    }
+    
+    /* We want our own pool with own allocator to keep data across watchdog invocations */
+    apr_allocator_create(&allocator);
+    apr_allocator_max_free_set(allocator, ap_max_mem_free);
+    rv = apr_pool_create_ex(&wdp, p, NULL, allocator);
+    if (rv != APR_SUCCESS) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO() "md_watchdog: create pool");
+        return rv;
+    }
+    apr_allocator_owner_set(allocator, wdp);
+    apr_pool_tag(wdp, "md_watchdog");
+
+    wd = apr_pcalloc(wdp, sizeof(*wd));
+    wd->p = wdp;
+    wd->reg = reg;
+    wd->s = s;
+    
+    wd->mds = apr_array_make(wd->p, 10, sizeof(md_t *));
+    for (i = 0; i < names->nelts; ++i) {
+        name = APR_ARRAY_IDX(names, i, const char *);
+        md = md_reg_get(wd->reg, name, wd->p);
+        if (md) {
+            md_reg_assess(wd->reg, md, &errored, &renew, wd->p);
+            if (errored) {
+                ap_log_error( APLOG_MARK, APLOG_WARNING, 0, wd->s, APLOGNO() 
+                             "md(%s): seems errored. Will not process this any further.", name);
+            }
+            else {
+                ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, wd->s, APLOGNO() 
+                             "md(%s): state=%d, driving", name, md->state);
+                APR_ARRAY_PUSH(wd->mds, md_t*) = md;
+            }
+        }
+    }
+
+    if (!wd->mds->nelts) {
+        ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO()
+                     "no managed domain in state to drive, no watchdog needed, "
+                     "will check again on next server restart");
+        apr_pool_destroy(wd->p);
+        return APR_SUCCESS;
+    }
+    
+    if (APR_SUCCESS != (rv = wd_get_instance(&wd->watchdog, MD_WATCHDOG_NAME, 0, 1, wd->p))) {
+        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO() 
+                     "create md watchdog(%s)", MD_WATCHDOG_NAME);
+        return rv;
+    }
+    rv = wd_register_callback(wd->watchdog, 0, wd, run_watchdog);
+    ap_log_error(APLOG_MARK, rv? APLOG_CRIT : APLOG_DEBUG, rv, s, APLOGNO() 
+                 "register md watchdog(%s)", MD_WATCHDOG_NAME);
+    return rv;
+}
+ 
+static void load_stage_sets(apr_array_header_t *names, apr_pool_t *p, 
+                            md_reg_t *reg, server_rec *s)
+{
+    const char *name; 
+    apr_status_t rv;
+    int i;
+    
+    for (i = 0; i < names->nelts; ++i) {
+        name = APR_ARRAY_IDX(names, i, const char*);
+        if (APR_SUCCESS == (rv = md_reg_load(reg, name, p))) {
+            ap_log_error( APLOG_MARK, APLOG_INFO, rv, s, APLOGNO() 
+                         "%s: staged set activated", name);
+        }
+        else if (!APR_STATUS_IS_ENOENT(rv)) {
+            ap_log_error( APLOG_MARK, APLOG_ERR, rv, s, APLOGNO()
+                         "%s: error loading staged set", name);
+        }
+    }
+    return;
+}
+
+static apr_status_t md_post_config(apr_pool_t *p, apr_pool_t *plog,
+                                   apr_pool_t *ptemp, server_rec *s)
+{
+    const char *mod_md_init_key = "mod_md_init_counter";
+    void *data = NULL;
+    md_ctx ctx;
+    apr_array_header_t *drive_names;
+    md_reg_t *reg;
+    apr_status_t rv = APR_SUCCESS;
+    const md_t *md;
+    int i;
+    
+    apr_pool_userdata_get(&data, mod_md_init_key, s->process->pool);
+    if (data == NULL) {
+        ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO()
+                     "initializing post config dry run");
+        apr_pool_userdata_set((const void *)1, mod_md_init_key,
+                              apr_pool_cleanup_null, s->process->pool);
+    }
+    else {
+        ap_log_error( APLOG_MARK, APLOG_INFO, 0, s, APLOGNO()
+                     "mod_md (v%s), initializing...", MOD_MD_VERSION);
+    }
+
+    init_setups(p, s);
+    memset(&ctx, 0, sizeof(ctx));
+    
+    md_log_set(log_is_level, log_print, NULL);
+
+    /* 1. Check uniqueness of MDs, calculate global, configured MD list.
+     * If successful, we have a list of MD definitions that do not overlap. */
+    /* We also need to find out if we can be reached on 80/443 from the outside (e.g. the CA) */
+    if (APR_SUCCESS != (rv = md_calc_md_list(&ctx, p, plog, ptemp, s))) {
+        goto out;
+    }
+    
+    /* 2. Check mappings of MDs to VirtulHosts defined.
+     * If successful, we have assigned MDs to server_recs in a unique way. Each server_rec
+     * config will carry 0 or 1 MD record. */
+    if (APR_SUCCESS != (rv = md_check_vhost_mapping(&ctx, p, plog, ptemp, s))) {
+        goto out;
+    }    
+    
+    /* 3. Synchronize the defintions we now have with the store via a registry (reg). */
+    if (APR_SUCCESS != (rv = setup_reg(&reg, p, s, 1))) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO()
+                     "setup md registry");
+        goto out;
+    }
+    if (APR_SUCCESS != (rv = md_reg_sync(reg, p, ptemp, ctx.mds, 
+                                         ctx.can_http, ctx.can_https))) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO()
+                     "synching %d mds to registry", ctx.mds->nelts);
+        goto out;
+    }
+    
+    /* Determine the managed domains that are in auto drive_mode. For those,
+     * determine in which state they are:
+     *  - UNKNOWN:            should not happen, report, dont drive
+     *  - ERROR:              something we do not know how to fix, report, dont drive
+     *  - INCOMPLETE/EXPIRED: need to drive them right away
+     *  - COMPLETE:           determine when cert expires, drive when the time comes
+     *
+     * Start the watchdog if we have anything, now or in the future.
+     */
+    drive_names = apr_array_make(ptemp, ctx.mds->nelts+1, sizeof(const char *));
+    for (i = 0; i < ctx.mds->nelts; ++i) {
+        md = APR_ARRAY_IDX(ctx.mds, i, const md_t *);
+        switch (md->drive_mode) {
+            case MD_DRIVE_AUTO:
+                if (md_array_str_index(ctx.unused_names, md->name, 0, 0) >= 0) {
+                    break;
+                }
+                /* fall through */
+            case MD_DRIVE_ALWAYS:
+                APR_ARRAY_PUSH(drive_names, const char *) = md->name; 
+                break;
+            default:
+                /* leave out */
+                break;
+        }
+    }
+    
+    if (drive_names->nelts > 0) {
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, s, APLOGNO()
+                     "%d out of %d mds are configured for auto-drive", 
+                     drive_names->nelts, ctx.mds->nelts);
+    
+        load_stage_sets(drive_names, p, reg, s);
+        md_http_use_implementation(md_curl_get_impl(p));
+        rv = start_watchdog(drive_names, p, reg, s);
+    }
+    else {
+        ap_log_error( APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO()
+                     "no mds to auto drive, no watchdog needed");
+    }
+out:     
+    return rv;
+}
+
+/**************************************************************************************************/
+/* Access API to other httpd components */
+
+static int md_is_managed(server_rec *s)
+{
+    md_config_t *conf = (md_config_t *)md_config_get(s);
+
+    if (conf && conf->md) {
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO() 
+                     "%s: manages server %s", conf->md->name, s->server_hostname);
+        return 1;
+    }
+    ap_log_error(APLOG_MARK, APLOG_TRACE1, 0, s,  
+                 "server %s is not managed", s->server_hostname);
+    return 0;
+}
+
+static apr_status_t md_get_credentials(server_rec *s, apr_pool_t *p,
+                                       const char **pkeyfile, const char **pcertfile,
+                                       const char **pchainfile)
+{
+    apr_status_t rv = APR_ENOENT;    
+    md_config_t *conf;
+    md_reg_t *reg;
+    const md_t *md;
+    
+    *pkeyfile = NULL;
+    *pcertfile = NULL;
+    *pchainfile = NULL;
+    conf = (md_config_t *)md_config_get(s);
+    
+    if (conf && conf->md && conf->store) {
+        if (APR_SUCCESS == (rv = md_reg_init(&reg, p, conf->store))) {
+            md = md_reg_get(reg, conf->md->name, p);
+            if (md->state != MD_S_COMPLETE) {
+                return APR_EAGAIN;
+            }
+            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO() 
+                         "%s: loading credentials for server %s", md->name, s->server_hostname);
+            return md_reg_get_cred_files(reg, md, p, pkeyfile, pcertfile, pchainfile);
+        }
+    }
+    return rv;
+}
+
+
+static int md_is_challenge(conn_rec *c, const char *servername,
+                           X509 **pcert, EVP_PKEY **pkey)
+{
+    md_config_t *conf;
+    apr_size_t slen, sufflen = sizeof(MD_TLSSNI01_DNS_SUFFIX) - 1;
+    apr_status_t rv;
+
+    slen = strlen(servername);
+    if (slen <= sufflen 
+        || apr_strnatcasecmp(MD_TLSSNI01_DNS_SUFFIX, servername + slen - sufflen)) {
+        return 0;
+    }
+    
+    conf = (md_config_t *)md_config_get(c->base_server);
+    if (conf && conf->store) {
+        md_store_t *store = conf->store;
+        md_cert_t *mdcert;
+        md_pkey_t *mdpkey;
+        
+        rv = md_store_load(store, MD_SG_CHALLENGES, servername, 
+                           MD_FN_TLSSNI01_CERT, MD_SV_CERT, (void**)&mdcert, c->pool);
+        if (APR_SUCCESS == rv && (*pcert = md_cert_get_X509(mdcert))) {
+            rv = md_store_load(store, MD_SG_CHALLENGES, servername, 
+                               MD_FN_TLSSNI01_PKEY, MD_SV_PKEY, (void**)&mdpkey, c->pool);
+            if (APR_SUCCESS == rv && (*pkey = md_pkey_get_EVP_PKEY(mdpkey))) {
+                ap_log_cerror(APLOG_MARK, APLOG_INFO, 0, c, APLOGNO()
+                              "%s: is a tls-sni-01 challenge host", servername);
+                return 1;
+            }
+            ap_log_cerror(APLOG_MARK, APLOG_WARNING, rv, c, APLOGNO()
+                          "%s: challenge data not complete, key unavailable", servername);
+        }
+        else {
+            ap_log_cerror(APLOG_MARK, APLOG_INFO, rv, c, APLOGNO()
+                          "%s: unknown TLS SNI challenge host", servername);
+        }
+    }
+    *pcert = NULL;
+    *pkey = NULL;
+    return 0;
+}
+
+/**************************************************************************************************/
+/* ACME challenge responses */
+
+#define ACME_CHALLENGE_PREFIX       "/.well-known/acme-challenge/"
+
+static int md_http_challenge_pr(request_rec *r)
+{
+    apr_bucket_brigade *bb;
+    const md_config_t *conf;
+    const char *base_dir, *name, *data;
+    apr_status_t rv;
+            
+    if (!strncmp(ACME_CHALLENGE_PREFIX, r->parsed_uri.path, sizeof(ACME_CHALLENGE_PREFIX)-1)) {
+        if (r->method_number == M_GET) {
+            md_store_t *store;
+        
+            conf = ap_get_module_config(r->server->module_config, &md_module);
+            store = conf->store;
+            
+            base_dir = md_config_gets(conf, MD_CONFIG_BASE_DIR);
+            name = r->parsed_uri.path + sizeof(ACME_CHALLENGE_PREFIX)-1;
+
+            r->status = HTTP_NOT_FOUND;
+            if (!ap_strchr_c(name, '/') && store) {
+                base_dir = ap_server_root_relative(r->pool, base_dir);
+                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, 
+                              "Challenge for %s (%s)", r->hostname, r->uri);
+
+                rv = md_store_load(store, MD_SG_CHALLENGES, r->hostname, 
+                                   MD_FN_HTTP01, MD_SV_TEXT, (void**)&data, r->pool);
+                if (APR_SUCCESS == rv) {
+                    apr_size_t len = strlen(data);
+                    
+                    r->status = HTTP_OK;
+                    apr_table_setn(r->headers_out, "Content-Length", apr_ltoa(r->pool, (long)len));
+                    
+                    bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
+                    apr_brigade_write(bb, NULL, NULL, data, len);
+                    ap_pass_brigade(r->output_filters, bb);
+                    apr_brigade_cleanup(bb);
+                }
+                else if (APR_STATUS_IS_ENOENT(rv)) {
+                    return HTTP_NOT_FOUND;
+                }
+                else if (APR_ENOENT != rv) {
+                    ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO()
+                                  "loading challenge %s from store %s", name, base_dir);
+                    return HTTP_INTERNAL_SERVER_ERROR;
+                }
+            }
+            return r->status;
+        }
+        else {
+            return HTTP_NOT_IMPLEMENTED;
+        }
+    }
+    return DECLINED;
+}
+
+/* Runs once per created child process. Perform any process 
+ * related initionalization here.
+ */
+static void md_child_init(apr_pool_t *pool, server_rec *s)
+{
+}
+
+/* Install this module into the apache2 infrastructure.
+ */
+static void md_hooks(apr_pool_t *pool)
+{
+    static const char *const mod_ssl[] = { "mod_ssl.c", NULL};
+
+    md_acme_init(pool, AP_SERVER_BASEVERSION);
+        
+    ap_log_perror(APLOG_MARK, APLOG_TRACE1, 0, pool, "installing hooks");
+    
+    /* Run once after configuration is set, before mod_ssl.
+     */
+    ap_hook_post_config(md_post_config, NULL, mod_ssl, APR_HOOK_MIDDLE);
+    
+    /* Run once after a child process has been created.
+     */
+    ap_hook_child_init(md_child_init, NULL, mod_ssl, APR_HOOK_MIDDLE);
+
+    /* answer challenges *very* early, before any configured authentication may strike */
+    ap_hook_post_read_request(md_http_challenge_pr, NULL, NULL, APR_HOOK_MIDDLE);
+
+    APR_REGISTER_OPTIONAL_FN(md_is_managed);
+    APR_REGISTER_OPTIONAL_FN(md_get_credentials);
+    APR_REGISTER_OPTIONAL_FN(md_is_challenge);
+}
diff --git a/modules/md/mod_md.h b/modules/md/mod_md.h
new file mode 100644
index 0000000000..40e4cd2c01
--- /dev/null
+++ b/modules/md/mod_md.h
@@ -0,0 +1,38 @@
+/* Copyright 2015 greenbytes GmbH (https://www.greenbytes.de)
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+#ifndef mod_md_mod_md_h
+#define mod_md_mod_md_h
+
+#include <openssl/evp.h>
+#include <openssl/x509v3.h>
+
+struct server_rec;
+
+APR_DECLARE_OPTIONAL_FN(int, 
+                        md_is_managed, (struct server_rec *));
+
+APR_DECLARE_OPTIONAL_FN(apr_status_t, 
+                        md_get_credentials, (struct server_rec *, apr_pool_t *,
+                                             const char **pkeyfile, 
+                                             const char **pcertfile, 
+                                             const char **pchainfile));
+
+APR_DECLARE_OPTIONAL_FN(int, 
+                        md_is_challenge, (struct conn_rec *, const char *,
+                                          X509 **pcert, EVP_PKEY **pkey));
+
+
+#endif /* mod_md_mod_md_h */