- djm@cvs.openbsd.org 2008/11/04 08:22:13

     [auth.h auth2.c monitor.c monitor.h monitor_wrap.c monitor_wrap.h]
     [readconf.c readconf.h servconf.c servconf.h ssh2.h ssh_config.5]
     [sshconnect2.c sshd_config.5 jpake.c jpake.h schnorr.c auth2-jpake.c]
     [Makefile.in]
     Add support for an experimental zero-knowledge password authentication
     method using the J-PAKE protocol described in F. Hao, P. Ryan,
     "Password Authenticated Key Exchange by Juggling", 16th Workshop on
     Security Protocols, Cambridge, April 2008.

     This method allows password-based authentication without exposing
     the password to the server. Instead, the client and server exchange
     cryptographic proofs to demonstrate of knowledge of the password while
     revealing nothing useful to an attacker or compromised endpoint.

     This is experimental, work-in-progress code and is presently
     compiled-time disabled (turn on -DJPAKE in Makefile.inc).

     "just commit it.  It isn't too intrusive." deraadt@

20 files changed, 2537 insertions, 25 deletions

diff --git a/ChangeLog b/ChangeLog
index cf80ff1e..012749b0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,25 @@
      [auth.c]
      need unistd.h for close() prototype
      (ID sync only)
+   - djm@cvs.openbsd.org 2008/11/04 08:22:13
+     [auth.h auth2.c monitor.c monitor.h monitor_wrap.c monitor_wrap.h]
+     [readconf.c readconf.h servconf.c servconf.h ssh2.h ssh_config.5]
+     [sshconnect2.c sshd_config.5 jpake.c jpake.h schnorr.c auth2-jpake.c]
+     [Makefile.in]
+     Add support for an experimental zero-knowledge password authentication
+     method using the J-PAKE protocol described in F. Hao, P. Ryan,
+     "Password Authenticated Key Exchange by Juggling", 16th Workshop on
+     Security Protocols, Cambridge, April 2008.
+     
+     This method allows password-based authentication without exposing
+     the password to the server. Instead, the client and server exchange
+     cryptographic proofs to demonstrate of knowledge of the password while
+     revealing nothing useful to an attacker or compromised endpoint.
+     
+     This is experimental, work-in-progress code and is presently
+     compiled-time disabled (turn on -DJPAKE in Makefile.inc).
+     
+     "just commit it.  It isn't too intrusive." deraadt@
 
 20081103
  - OpenBSD CVS Sync
@@ -4857,4 +4876,4 @@
    OpenServer 6 and add osr5bigcrypt support so when someone migrates
    passwords between UnixWare and OpenServer they will still work. OK dtucker@
 
-$Id: ChangeLog,v 1.5129 2008/11/05 05:12:54 djm Exp $
+$Id: ChangeLog,v 1.5130 2008/11/05 05:20:46 djm Exp $
diff --git a/Makefile.in b/Makefile.in
index c1b7ab5a..312b8d2b 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,4 +1,4 @@
-# $Id: Makefile.in,v 1.297 2008/07/08 14:21:12 djm Exp $
+# $Id: Makefile.in,v 1.298 2008/11/05 05:20:46 djm Exp $
 
 # uncomment if you run a non bourne compatable shell. Ie. csh
 #SHELL = @SH@
@@ -71,7 +71,7 @@ LIBSSH_OBJS=acss.o authfd.o authfile.o bufaux.o bufbn.o buffer.o \
 	atomicio.o key.o dispatch.o kex.o mac.o uidswap.o uuencode.o misc.o \
 	monitor_fdpass.o rijndael.o ssh-dss.o ssh-rsa.o dh.o kexdh.o \
 	kexgex.o kexdhc.o kexgexc.o scard.o msg.o progressmeter.o dns.o \
-	entropy.o scard-opensc.o gss-genr.o umac.o
+	entropy.o scard-opensc.o gss-genr.o umac.o jpake.o schnorr.o
 
 SSHOBJS= ssh.o readconf.o clientloop.o sshtty.o \
 	sshconnect.o sshconnect1.o sshconnect2.o mux.o
@@ -81,7 +81,7 @@ SSHDOBJS=sshd.o auth-rhosts.o auth-passwd.o auth-rsa.o auth-rh-rsa.o \
 	auth.o auth1.o auth2.o auth-options.o session.o \
 	auth-chall.o auth2-chall.o groupaccess.o \
 	auth-skey.o auth-bsdauth.o auth2-hostbased.o auth2-kbdint.o \
-	auth2-none.o auth2-passwd.o auth2-pubkey.o \
+	auth2-none.o auth2-passwd.o auth2-pubkey.o auth2-jpake.o \
 	monitor_mm.o monitor.o monitor_wrap.o kexdhs.o kexgexs.o \
 	auth-krb5.o \
 	auth2-gss.o gss-serv.o gss-serv-krb5.o \
diff --git a/auth.h b/auth.h
index 6a70f0eb..3a70f442 100644
--- a/auth.h
+++ b/auth.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.h,v 1.61 2008/07/02 12:03:51 dtucker Exp $ */
+/* $OpenBSD: auth.h,v 1.62 2008/11/04 08:22:12 djm Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -59,6 +59,7 @@ struct Authctxt {
 	struct passwd	*pw;		/* set if 'valid' */
 	char		*style;
 	void		*kbdintctxt;
+	void		*jpake_ctx;
 #ifdef BSD_AUTH
 	auth_session_t	*as;
 #endif
@@ -156,6 +157,9 @@ int	bsdauth_respond(void *, u_int, char **);
 int	skey_query(void *, char **, char **, u_int *, char ***, u_int **);
 int	skey_respond(void *, u_int, char **);
 
+void	auth2_jpake_get_pwdata(Authctxt *, BIGNUM **, char **, char **);
+void	auth2_jpake_stop(Authctxt *);
+
 int	allowed_user(struct passwd *);
 struct passwd * getpwnamallow(const char *user);
 
diff --git a/auth2-jpake.c b/auth2-jpake.c
new file mode 100644
index 00000000..0029ec26
--- /dev/null
+++ b/auth2-jpake.c
@@ -0,0 +1,557 @@
+/* $OpenBSD: auth2-jpake.c,v 1.1 2008/11/04 08:22:12 djm Exp $ */
+/*
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Server side of zero-knowledge password auth using J-PAKE protocol
+ * as described in:
+ *
+ * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
+ * 16th Workshop on Security Protocols, Cambridge, April 2008
+ *
+ * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
+ */
+
+#include <sys/types.h>
+#include <sys/param.h>
+
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+#include <login_cap.h>
+
+#include <openssl/bn.h>
+#include <openssl/evp.h>
+
+#include "xmalloc.h"
+#include "ssh2.h"
+#include "key.h"
+#include "hostfile.h"
+#include "buffer.h"
+#include "auth.h"
+#include "packet.h"
+#include "dispatch.h"
+#include "log.h"
+#include "servconf.h"
+#include "auth-options.h"
+#include "canohost.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
+#include "monitor_wrap.h"
+
+#include "jpake.h"
+
+#ifdef JPAKE
+
+/*
+ * XXX options->permit_empty_passwd (at the moment, they will be refused
+ * anyway because they will mismatch on fake salt.
+ */
+
+/* Dispatch handlers */
+static void input_userauth_jpake_client_step1(int, u_int32_t, void *);
+static void input_userauth_jpake_client_step2(int, u_int32_t, void *);
+static void input_userauth_jpake_client_confirm(int, u_int32_t, void *);
+
+static int auth2_jpake_start(Authctxt *);
+
+/* import */
+extern ServerOptions options;
+extern u_char *session_id2;
+extern u_int session_id2_len;
+
+/*
+ * Attempt J-PAKE authentication.
+ */
+static int
+userauth_jpake(Authctxt *authctxt)
+{
+	int authenticated = 0;
+
+	packet_check_eom();
+
+	debug("jpake-01@openssh.com requested");
+
+	if (authctxt->user != NULL) {
+		if (authctxt->jpake_ctx == NULL)
+			authctxt->jpake_ctx = jpake_new();
+		if (options.zero_knowledge_password_authentication)
+			authenticated = auth2_jpake_start(authctxt);
+	}
+
+	return authenticated;
+}
+
+Authmethod method_jpake = {
+	"jpake-01@openssh.com",
+	userauth_jpake,
+	&options.zero_knowledge_password_authentication
+};
+
+/* Clear context and callbacks */
+void
+auth2_jpake_stop(Authctxt *authctxt)
+{
+	/* unregister callbacks */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL);
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL);
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL);
+	if (authctxt->jpake_ctx != NULL) {
+		jpake_free(authctxt->jpake_ctx);
+		authctxt->jpake_ctx = NULL;
+	}
+}
+
+/* Returns 1 if 'c' is a valid crypt(3) salt character, 0 otherwise */
+static int
+valid_crypt_salt(int c)
+{
+	if (c >= 'A' && c <= 'Z')
+		return 1;
+	if (c >= 'a' && c <= 'z')
+		return 1;
+	if (c >= '.' && c <= '9')
+		return 1;
+	return 0;
+}
+
+/*
+ * Derive fake salt as H(username || first_private_host_key)
+ * This provides relatively stable fake salts for non-existent
+ * users and avoids the jpake method becoming an account validity
+ * oracle.
+ */
+static void
+derive_rawsalt(const char *username, u_char *rawsalt, u_int len)
+{
+	u_char *digest;
+	u_int digest_len;
+	Buffer b;
+	Key *k;
+
+	buffer_init(&b);
+	buffer_put_cstring(&b, username);
+	if ((k = get_hostkey_by_index(0)) == NULL ||
+	    (k->flags & KEY_FLAG_EXT))
+		fatal("%s: no hostkeys", __func__);
+	switch (k->type) {
+	case KEY_RSA1:
+	case KEY_RSA:
+		if (k->rsa->p == NULL || k->rsa->q == NULL)
+			fatal("%s: RSA key missing p and/or q", __func__);
+		buffer_put_bignum2(&b, k->rsa->p);
+		buffer_put_bignum2(&b, k->rsa->q);
+		break;
+	case KEY_DSA:
+		if (k->dsa->priv_key == NULL)
+			fatal("%s: DSA key missing priv_key", __func__);
+		buffer_put_bignum2(&b, k->dsa->priv_key);
+		break;
+	default:
+		fatal("%s: unknown key type %d", __func__, k->type);
+	}
+	if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(),
+	    &digest, &digest_len) != 0)
+		fatal("%s: hash_buffer", __func__);
+	buffer_free(&b);
+	if (len > digest_len)
+		fatal("%s: not enough bytes for rawsalt (want %u have %u)",
+		    __func__, len, digest_len);
+	memcpy(rawsalt, digest, len);
+	bzero(digest, digest_len);
+	xfree(digest);
+}
+
+/* ASCII an integer [0, 64) for inclusion in a password/salt */
+static char
+pw_encode64(u_int i64)
+{
+	const u_char e64[] =
+	    "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+	return e64[i64 % 64];
+}
+
+/* Generate ASCII salt bytes for user */
+static char *
+makesalt(u_int want, const char *user)
+{
+	u_char rawsalt[32];
+	static char ret[33];
+	u_int i;
+
+	if (want > sizeof(ret) - 1)
+		fatal("%s: want %u", __func__, want);
+
+	derive_rawsalt(user, rawsalt, sizeof(rawsalt));
+	bzero(ret, sizeof(ret));
+	for (i = 0; i < want; i++)
+		ret[i] = pw_encode64(rawsalt[i]);
+	bzero(rawsalt, sizeof(rawsalt));
+
+	return ret;
+}
+
+/*
+ * Select the system's default password hashing scheme and generate
+ * a stable fake salt under it for use by a non-existent account.
+ * Prevents jpake method being used to infer the validity of accounts.
+ */
+static void
+fake_salt_and_scheme(Authctxt *authctxt, char **salt, char **scheme)
+{
+	char *rounds_s, *style;
+	long long rounds;
+	login_cap_t *lc;
+
+
+	if ((lc = login_getclass(authctxt->pw->pw_class)) == NULL &&
+	    (lc = login_getclass(NULL)) == NULL)
+		fatal("%s: login_getclass failed", __func__);
+	style = login_getcapstr(lc, "localcipher", NULL, NULL);
+	if (style == NULL)
+		style = xstrdup("blowfish,6");
+	login_close(lc);
+	
+	if ((rounds_s = strchr(style, ',')) != NULL)
+		*rounds_s++ = '\0';
+	rounds = strtonum(rounds_s, 1, 1<<31, NULL);
+	
+	if (strcmp(style, "md5") == 0) {
+		xasprintf(salt, "$1$%s$", makesalt(8, authctxt->user));
+		*scheme = xstrdup("md5");
+	} else if (strcmp(style, "old") == 0) {
+		*salt = xstrdup(makesalt(2, authctxt->user));
+		*scheme = xstrdup("crypt");
+	} else if (strcmp(style, "newsalt") == 0) {
+		rounds = MAX(rounds, 7250);
+		rounds = MIN(rounds, (1<<24) - 1);
+		xasprintf(salt, "_%c%c%c%c%s",
+		    pw_encode64(rounds), pw_encode64(rounds >> 6),
+		    pw_encode64(rounds >> 12), pw_encode64(rounds >> 18),
+		    makesalt(4, authctxt->user));
+		*scheme = xstrdup("crypt-extended");
+	} else {
+		/* Default to blowfish */
+		rounds = MAX(rounds, 3);
+		rounds = MIN(rounds, 31);
+		xasprintf(salt, "$2a$%02lld$%s", rounds,
+		    makesalt(22, authctxt->user));
+		*scheme = xstrdup("bcrypt");
+	}
+	xfree(style);
+	debug3("%s: fake %s salt for user %s: %s",
+	    __func__, *scheme, authctxt->user, *salt);
+}
+
+/*
+ * Fetch password hashing scheme, password salt and derive shared secret
+ * for user. If user does not exist, a fake but stable and user-unique
+ * salt will be returned.
+ */
+void
+auth2_jpake_get_pwdata(Authctxt *authctxt, BIGNUM **s,
+    char **hash_scheme, char **salt)
+{
+	char *cp;
+	u_char *secret;
+	u_int secret_len, salt_len;
+
+#ifdef JPAKE_DEBUG
+	debug3("%s: valid %d pw %.5s...", __func__,
+	    authctxt->valid, authctxt->pw->pw_passwd);
+#endif
+
+	*salt = NULL;
+	*hash_scheme = NULL;
+	if (authctxt->valid) {
+		if (strncmp(authctxt->pw->pw_passwd, "$2$", 3) == 0 &&
+		    strlen(authctxt->pw->pw_passwd) > 28) {
+			/*
+			 * old-variant bcrypt:
+			 *     "$2$", 2 digit rounds, "$", 22 bytes salt
+			 */
+			salt_len = 3 + 2 + 1 + 22 + 1;
+			*salt = xmalloc(salt_len);
+			strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+			*hash_scheme = xstrdup("bcrypt");
+		} else if (strncmp(authctxt->pw->pw_passwd, "$2a$", 4) == 0 &&
+		    strlen(authctxt->pw->pw_passwd) > 29) {
+			/*
+			 * current-variant bcrypt:
+			 *     "$2a$", 2 digit rounds, "$", 22 bytes salt
+			 */
+			salt_len = 4 + 2 + 1 + 22 + 1;
+			*salt = xmalloc(salt_len);
+			strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+			*hash_scheme = xstrdup("bcrypt");
+		} else if (strncmp(authctxt->pw->pw_passwd, "$1$", 3) == 0 &&
+		    strlen(authctxt->pw->pw_passwd) > 5) {
+			/*
+			 * md5crypt:
+			 *     "$1$", salt until "$"
+			 */
+			cp = strchr(authctxt->pw->pw_passwd + 3, '$');
+			if (cp != NULL) {
+				salt_len = (cp - authctxt->pw->pw_passwd) + 1;
+				*salt = xmalloc(salt_len);
+				strlcpy(*salt, authctxt->pw->pw_passwd,
+				    salt_len);
+				*hash_scheme = xstrdup("md5crypt");
+			}
+		} else if (strncmp(authctxt->pw->pw_passwd, "_", 1) == 0 &&
+		    strlen(authctxt->pw->pw_passwd) > 9) {
+			/*
+			 * BSDI extended crypt:
+			 *     "_", 4 digits count, 4 chars salt
+			 */
+			salt_len = 1 + 4 + 4 + 1;
+			*salt = xmalloc(salt_len);
+			strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+			*hash_scheme = xstrdup("crypt-extended");
+		} else if (strlen(authctxt->pw->pw_passwd) == 13  &&
+		    valid_crypt_salt(authctxt->pw->pw_passwd[0]) &&
+		    valid_crypt_salt(authctxt->pw->pw_passwd[1])) {
+			/*
+			 * traditional crypt:
+			 *     2 chars salt
+			 */
+			salt_len = 2 + 1;
+			*salt = xmalloc(salt_len);
+			strlcpy(*salt, authctxt->pw->pw_passwd, salt_len);
+			*hash_scheme = xstrdup("crypt");
+		}
+		if (*salt == NULL) {
+			debug("%s: unrecognised crypt scheme for user %s",
+			    __func__, authctxt->pw->pw_name);
+		}
+	}
+	if (*salt == NULL)
+		fake_salt_and_scheme(authctxt, salt, hash_scheme);
+
+	if (hash_buffer(authctxt->pw->pw_passwd,
+	    strlen(authctxt->pw->pw_passwd), EVP_sha256(),
+	    &secret, &secret_len) != 0)
+		fatal("%s: hash_buffer", __func__);
+	if ((*s = BN_bin2bn(secret, secret_len, NULL)) == NULL)
+		fatal("%s: BN_bin2bn (secret)", __func__);
+#ifdef JPAKE_DEBUG
+	debug3("%s: salt = %s (len %u)", __func__,
+	    *salt, (u_int)strlen(*salt));
+	debug3("%s: scheme = %s", __func__, *hash_scheme);
+	JPAKE_DEBUG_BN((*s, "%s: s = ", __func__));
+#endif
+	bzero(secret, secret_len);
+	xfree(secret);
+}
+
+/*
+ * Being authentication attempt.
+ * Note, sets authctxt->postponed while in subprotocol
+ */
+static int
+auth2_jpake_start(Authctxt *authctxt)
+{
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	u_char *x3_proof, *x4_proof;
+	u_int x3_proof_len, x4_proof_len;
+	char *salt, *hash_scheme;
+
+	debug("%s: start", __func__);
+
+	PRIVSEP(jpake_step1(pctx->grp,
+	    &pctx->server_id, &pctx->server_id_len,
+	    &pctx->x3, &pctx->x4, &pctx->g_x3, &pctx->g_x4,
+	    &x3_proof, &x3_proof_len,
+	    &x4_proof, &x4_proof_len));
+
+	PRIVSEP(auth2_jpake_get_pwdata(authctxt, &pctx->s,
+	    &hash_scheme, &salt));
+
+	if (!use_privsep)
+		JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
+
+	packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1);
+	packet_put_cstring(hash_scheme);
+	packet_put_cstring(salt);
+	packet_put_string(pctx->server_id, pctx->server_id_len);
+	packet_put_bignum2(pctx->g_x3);
+	packet_put_bignum2(pctx->g_x4);
+	packet_put_string(x3_proof, x3_proof_len);
+	packet_put_string(x4_proof, x4_proof_len);
+	packet_send();
+	packet_write_wait();
+
+	bzero(hash_scheme, strlen(hash_scheme));
+	bzero(salt, strlen(salt));
+	xfree(hash_scheme);
+	xfree(salt);
+	bzero(x3_proof, x3_proof_len);
+	bzero(x4_proof, x4_proof_len);
+	xfree(x3_proof);
+	xfree(x4_proof);
+
+	/* Expect step 1 packet from peer */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1,
+	    input_userauth_jpake_client_step1);
+
+	authctxt->postponed = 1;
+	return 0;
+}
+
+/* ARGSUSED */
+static void
+input_userauth_jpake_client_step1(int type, u_int32_t seq, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	u_char *x1_proof, *x2_proof, *x4_s_proof;
+	u_int x1_proof_len, x2_proof_len, x4_s_proof_len;
+
+	/* Disable this message */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1, NULL);
+
+	/* Fetch step 1 values */
+	if ((pctx->g_x1 = BN_new()) == NULL ||
+	    (pctx->g_x2 = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+	pctx->client_id = packet_get_string(&pctx->client_id_len);
+	packet_get_bignum2(pctx->g_x1);
+	packet_get_bignum2(pctx->g_x2);
+	x1_proof = packet_get_string(&x1_proof_len);
+	x2_proof = packet_get_string(&x2_proof_len);
+	packet_check_eom();
+
+	if (!use_privsep)
+		JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
+
+	PRIVSEP(jpake_step2(pctx->grp, pctx->s, pctx->g_x3,
+	    pctx->g_x1, pctx->g_x2, pctx->x4,
+	    pctx->client_id, pctx->client_id_len,
+	    pctx->server_id, pctx->server_id_len,
+	    x1_proof, x1_proof_len,
+	    x2_proof, x2_proof_len,
+	    &pctx->b,
+	    &x4_s_proof, &x4_s_proof_len));
+
+	bzero(x1_proof, x1_proof_len);
+	bzero(x2_proof, x2_proof_len);
+	xfree(x1_proof);
+	xfree(x2_proof);
+
+	if (!use_privsep)
+		JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
+
+	/* Send values for step 2 */
+	packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2);
+	packet_put_bignum2(pctx->b);
+	packet_put_string(x4_s_proof, x4_s_proof_len);
+	packet_send();
+	packet_write_wait();
+
+	bzero(x4_s_proof, x4_s_proof_len);
+	xfree(x4_s_proof);
+
+	/* Expect step 2 packet from peer */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2,
+	    input_userauth_jpake_client_step2);
+}
+
+/* ARGSUSED */
+static void
+input_userauth_jpake_client_step2(int type, u_int32_t seq, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	u_char *x2_s_proof;
+	u_int x2_s_proof_len;
+
+	/* Disable this message */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2, NULL);
+
+	if ((pctx->a = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	/* Fetch step 2 values */
+	packet_get_bignum2(pctx->a);
+	x2_s_proof = packet_get_string(&x2_s_proof_len);
+	packet_check_eom();
+
+	if (!use_privsep)
+		JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
+
+	/* Derive shared key and calculate confirmation hash */
+	PRIVSEP(jpake_key_confirm(pctx->grp, pctx->s, pctx->a,
+	    pctx->x4, pctx->g_x3, pctx->g_x4, pctx->g_x1, pctx->g_x2,
+	    pctx->server_id, pctx->server_id_len,
+	    pctx->client_id, pctx->client_id_len,
+	    session_id2, session_id2_len,
+	    x2_s_proof, x2_s_proof_len,
+	    &pctx->k,
+	    &pctx->h_k_sid_sessid, &pctx->h_k_sid_sessid_len));
+
+	bzero(x2_s_proof, x2_s_proof_len);
+	xfree(x2_s_proof);
+
+	if (!use_privsep)
+		JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
+
+	/* Send key confirmation proof */
+	packet_start(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM);
+	packet_put_string(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len);
+	packet_send();
+	packet_write_wait();
+
+	/* Expect confirmation from peer */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM,
+	    input_userauth_jpake_client_confirm);
+}
+
+/* ARGSUSED */
+static void
+input_userauth_jpake_client_confirm(int type, u_int32_t seq, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	int authenticated = 0;
+
+	/* Disable this message */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM, NULL);
+
+	pctx->h_k_cid_sessid = packet_get_string(&pctx->h_k_cid_sessid_len);
+	packet_check_eom();
+
+	if (!use_privsep)
+		JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
+
+	/* Verify expected confirmation hash */
+	if (PRIVSEP(jpake_check_confirm(pctx->k,
+	    pctx->client_id, pctx->client_id_len,
+	    session_id2, session_id2_len,
+	    pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len)) == 1)
+		authenticated = authctxt->valid ? 1 : 0;
+	else
+		debug("%s: confirmation mismatch", __func__);
+		
+	/* done */
+	authctxt->postponed = 0;
+	jpake_free(authctxt->jpake_ctx);
+	authctxt->jpake_ctx = NULL;
+	userauth_finish(authctxt, authenticated, method_jpake.name);
+}
+
+#endif /* JPAKE */
+
diff --git a/auth2.c b/auth2.c
index a835abfc..ecf85705 100644
--- a/auth2.c
+++ b/auth2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2.c,v 1.119 2008/07/04 23:30:16 djm Exp $ */
+/* $OpenBSD: auth2.c,v 1.120 2008/11/04 08:22:12 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -71,6 +71,9 @@ extern Authmethod method_hostbased;
 #ifdef GSSAPI
 extern Authmethod method_gssapi;
 #endif
+#ifdef JPAKE
+extern Authmethod method_jpake;
+#endif
 
 Authmethod *authmethods[] = {
 	&method_none,
@@ -78,6 +81,9 @@ Authmethod *authmethods[] = {
 #ifdef GSSAPI
 	&method_gssapi,
 #endif
+#ifdef JPAKE
+	&method_jpake,
+#endif
 	&method_passwd,
 	&method_kbdint,
 	&method_hostbased,
@@ -257,8 +263,12 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
 	}
 	/* reset state */
 	auth2_challenge_stop(authctxt);
+#ifdef JPAKE
+	auth2_jpake_stop(authctxt);
+#endif
 
 #ifdef GSSAPI
+	/* XXX move to auth2_gssapi_stop() */
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
 #endif
diff --git a/jpake.c b/jpake.c
new file mode 100644
index 00000000..565f2e25
--- /dev/null
+++ b/jpake.c
@@ -0,0 +1,604 @@
+/* $OpenBSD: jpake.c,v 1.1 2008/11/04 08:22:12 djm Exp $ */
+/*
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Shared components of zero-knowledge password auth using J-PAKE protocol
+ * as described in:
+ *
+ * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
+ * 16th Workshop on Security Protocols, Cambridge, April 2008
+ *
+ * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include <openssl/bn.h>
+#include <openssl/evp.h>
+
+#include "xmalloc.h"
+#include "ssh2.h"
+#include "key.h"
+#include "hostfile.h"
+#include "auth.h"
+#include "buffer.h"
+#include "packet.h"
+#include "dispatch.h"
+#include "log.h"
+
+#include "jpake.h"
+
+#ifdef JPAKE
+
+/* RFC3526 group 5, 1536 bits */
+#define JPAKE_GROUP_G "2"
+#define JPAKE_GROUP_P \
+	"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74" \
+	"020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F1437" \
+	"4FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" \
+	"EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF05" \
+	"98DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB" \
+	"9ED529077096966D670C354E4ABC9804F1746C08CA237327FFFFFFFFFFFFFFFF"
+
+struct jpake_group *
+jpake_default_group(void)
+{
+	struct jpake_group *ret;
+
+	ret = xmalloc(sizeof(*ret));
+	ret->p = ret->q = ret->g = NULL;
+	if (BN_hex2bn(&ret->p, JPAKE_GROUP_P) == 0 ||
+	    BN_hex2bn(&ret->g, JPAKE_GROUP_G) == 0)
+		fatal("%s: BN_hex2bn", __func__);
+	/* Subgroup order is p/2 (p is a safe prime) */
+	if ((ret->q = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+	if (BN_rshift1(ret->q, ret->p) != 1)
+		fatal("%s: BN_rshift1", __func__);
+
+	return ret;
+}
+
+/*
+ * Generate uniformly distributed random number in range (1, high).
+ * Return number on success, NULL on failure.
+ */
+BIGNUM *
+bn_rand_range_gt_one(const BIGNUM *high)
+{
+	BIGNUM *r, *tmp;
+	int success = -1;
+
+	if ((tmp = BN_new()) == NULL) {
+		error("%s: BN_new", __func__);
+		return NULL;
+	}
+	if ((r = BN_new()) == NULL) {
+		error("%s: BN_new failed", __func__);
+		goto out;
+	}
+	if (BN_set_word(tmp, 2) != 1) {
+		error("%s: BN_set_word(tmp, 2)", __func__);
+		goto out;
+	}
+	if (BN_sub(tmp, high, tmp) == -1) {
+		error("%s: BN_sub failed (tmp = high - 2)", __func__);
+		goto out;
+	}
+	if (BN_rand_range(r, tmp) == -1) {
+		error("%s: BN_rand_range failed", __func__);
+		goto out;
+	}
+	if (BN_set_word(tmp, 2) != 1) {
+		error("%s: BN_set_word(tmp, 2)", __func__);
+		goto out;
+	}
+	if (BN_add(r, r, tmp) == -1) {
+		error("%s: BN_add failed (r = r + 2)", __func__);
+		goto out;
+	}
+	success = 0;
+ out:
+	BN_clear_free(tmp);
+	if (success == 0)
+		return r;
+	BN_clear_free(r);
+	return NULL;
+}
+
+/*
+ * Hash contents of buffer 'b' with hash 'md'. Returns 0 on success,
+ * with digest via 'digestp' (caller to free) and length via 'lenp'.
+ * Returns -1 on failure.
+ */
+int
+hash_buffer(const u_char *buf, u_int len, const EVP_MD *md,
+    u_char **digestp, u_int *lenp)
+{
+	u_char digest[EVP_MAX_MD_SIZE];
+	u_int digest_len;
+	EVP_MD_CTX evp_md_ctx;
+	int success = -1;
+
+	EVP_MD_CTX_init(&evp_md_ctx);
+
+	if (EVP_DigestInit_ex(&evp_md_ctx, md, NULL) != 1) {
+		error("%s: EVP_DigestInit_ex", __func__);
+		goto out;
+	}
+	if (EVP_DigestUpdate(&evp_md_ctx, buf, len) != 1) {
+		error("%s: EVP_DigestUpdate", __func__);
+		goto out;
+	}
+	if (EVP_DigestFinal_ex(&evp_md_ctx, digest, &digest_len) != 1) {
+		error("%s: EVP_DigestFinal_ex", __func__);
+		goto out;
+	}
+	*digestp = xmalloc(digest_len);
+	*lenp = digest_len;
+	memcpy(*digestp, digest, *lenp);
+	success = 0;
+ out:
+	EVP_MD_CTX_cleanup(&evp_md_ctx);
+	bzero(digest, sizeof(digest));
+	digest_len = 0;
+	return success;
+}
+
+/* print formatted string followed by bignum */
+void
+jpake_debug3_bn(const BIGNUM *n, const char *fmt, ...)
+{
+	char *out, *h;
+	va_list args;
+
+	out = NULL;
+	va_start(args, fmt);
+	vasprintf(&out, fmt, args);
+	va_end(args);
+	if (out == NULL)
+		fatal("%s: vasprintf failed", __func__);
+
+	if (n == NULL)
+		debug3("%s(null)", out);
+	else {
+		h = BN_bn2hex(n);
+		debug3("%s0x%s", out, h);
+		free(h);
+	}
+	free(out);
+}
+
+/* print formatted string followed by buffer contents in hex */
+void
+jpake_debug3_buf(const u_char *buf, u_int len, const char *fmt, ...)
+{
+	char *out, h[65];
+	u_int i, j;
+	va_list args;
+
+	out = NULL;
+	va_start(args, fmt);
+	vasprintf(&out, fmt, args);
+	va_end(args);
+	if (out == NULL)
+		fatal("%s: vasprintf failed", __func__);
+
+	debug3("%s length %u%s", out, len, buf == NULL ? " (null)" : "");
+	free(out);
+	if (buf == NULL)
+		return;
+
+	*h = '\0';
+	for (i = j = 0; i < len; i++) {
+		snprintf(h + j, sizeof(h) - j, "%02x", buf[i]);
+		j += 2;
+		if (j >= sizeof(h) - 1 || i == len - 1) {
+			debug3("    %s", h);
+			*h = '\0';
+			j = 0;
+		}
+	}
+}
+
+struct jpake_ctx *
+jpake_new(void)
+{
+	struct jpake_ctx *ret;
+
+	ret = xcalloc(1, sizeof(*ret));
+
+	ret->grp = jpake_default_group();
+
+	ret->s = ret->k = NULL;
+	ret->x1 = ret->x2 = ret->x3 = ret->x4 = NULL;
+	ret->g_x1 = ret->g_x2 = ret->g_x3 = ret->g_x4 = NULL;
+	ret->a = ret->b = NULL;
+
+	ret->client_id = ret->server_id = NULL;
+	ret->h_k_cid_sessid = ret->h_k_sid_sessid = NULL;
+
+	debug3("%s: alloc %p", __func__, ret);
+
+	return ret;
+}
+
+
+void
+jpake_free(struct jpake_ctx *pctx)
+{
+	debug3("%s: free %p", __func__, pctx);
+
+#define JPAKE_BN_CLEAR_FREE(v)			\
+	do {					\
+		if ((v) != NULL) {		\
+			BN_clear_free(v);	\
+			(v) = NULL;		\
+		}				\
+	} while (0)
+#define JPAKE_BUF_CLEAR_FREE(v, l)		\
+	do {					\
+		if ((v) != NULL) {		\
+			bzero((v), (l));	\
+			xfree(v);		\
+			(v) = NULL;		\
+			(l) = 0;		\
+		}				\
+	} while (0)
+
+	JPAKE_BN_CLEAR_FREE(pctx->s);
+	JPAKE_BN_CLEAR_FREE(pctx->k);
+	JPAKE_BN_CLEAR_FREE(pctx->x1);
+	JPAKE_BN_CLEAR_FREE(pctx->x2);
+	JPAKE_BN_CLEAR_FREE(pctx->x3);
+	JPAKE_BN_CLEAR_FREE(pctx->x4);
+	JPAKE_BN_CLEAR_FREE(pctx->g_x1);
+	JPAKE_BN_CLEAR_FREE(pctx->g_x2);
+	JPAKE_BN_CLEAR_FREE(pctx->g_x3);
+	JPAKE_BN_CLEAR_FREE(pctx->g_x4);
+	JPAKE_BN_CLEAR_FREE(pctx->a);
+	JPAKE_BN_CLEAR_FREE(pctx->b);
+
+	JPAKE_BUF_CLEAR_FREE(pctx->client_id, pctx->client_id_len);
+	JPAKE_BUF_CLEAR_FREE(pctx->server_id, pctx->server_id_len);
+	JPAKE_BUF_CLEAR_FREE(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
+	JPAKE_BUF_CLEAR_FREE(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len);
+
+#undef JPAKE_BN_CLEAR_FREE
+#undef JPAKE_BUF_CLEAR_FREE
+
+	bzero(pctx, sizeof(pctx));
+	xfree(pctx);
+}
+
+/* dump entire jpake_ctx. NB. includes private values! */
+void
+jpake_dump(struct jpake_ctx *pctx, const char *fmt, ...)
+{
+	char *out;
+	va_list args;
+
+	out = NULL;
+	va_start(args, fmt);
+	vasprintf(&out, fmt, args);
+	va_end(args);
+	if (out == NULL)
+		fatal("%s: vasprintf failed", __func__);
+
+	debug3("%s: %s (ctx at %p)", __func__, out, pctx);
+	if (pctx == NULL) {
+		free(out);
+		return;
+	}
+
+#define JPAKE_DUMP_BN(a)	do { \
+		if ((a) != NULL) \
+			JPAKE_DEBUG_BN(((a), "%s = ", #a)); \
+	} while (0)
+#define JPAKE_DUMP_BUF(a, b)	do { \
+		if ((a) != NULL) \
+			JPAKE_DEBUG_BUF((a, b, "%s", #a)); \
+	} while (0)
+
+	JPAKE_DUMP_BN(pctx->s);
+	JPAKE_DUMP_BN(pctx->k);
+	JPAKE_DUMP_BN(pctx->x1);
+	JPAKE_DUMP_BN(pctx->x2);
+	JPAKE_DUMP_BN(pctx->x3);
+	JPAKE_DUMP_BN(pctx->x4);
+	JPAKE_DUMP_BN(pctx->g_x1);
+	JPAKE_DUMP_BN(pctx->g_x2);
+	JPAKE_DUMP_BN(pctx->g_x3);
+	JPAKE_DUMP_BN(pctx->g_x4);
+	JPAKE_DUMP_BN(pctx->a);
+	JPAKE_DUMP_BN(pctx->b);
+
+	JPAKE_DUMP_BUF(pctx->client_id, pctx->client_id_len);
+	JPAKE_DUMP_BUF(pctx->server_id, pctx->server_id_len);
+	JPAKE_DUMP_BUF(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
+	JPAKE_DUMP_BUF(pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len);
+
+	debug3("%s: %s done", __func__, out);
+	free(out);
+}
+
+/* Shared parts of step 1 exchange calculation */
+void
+jpake_step1(struct jpake_group *grp,
+    u_char **id, u_int *id_len,
+    BIGNUM **priv1, BIGNUM **priv2, BIGNUM **g_priv1, BIGNUM **g_priv2,
+    u_char **priv1_proof, u_int *priv1_proof_len,
+    u_char **priv2_proof, u_int *priv2_proof_len)
+{
+	BN_CTX *bn_ctx;
+
+	if ((bn_ctx = BN_CTX_new()) == NULL)
+		fatal("%s: BN_CTX_new", __func__);
+
+	/* Random nonce to prevent replay */
+	*id = xmalloc(KZP_ID_LEN);
+	*id_len = KZP_ID_LEN;
+	arc4random_buf(*id, *id_len);
+
+	/*
+	 * x1/x3 is a random element of Zq
+	 * x2/x4 is a random element of Z*q
+	 * We also exclude [1] from x1/x3 candidates and [0, 1] from
+	 * x2/x4 candiates to avoid possible degeneracy (i.e. g^0, g^1).
+	 */
+	if ((*priv1 = bn_rand_range_gt_one(grp->q)) == NULL ||
+	    (*priv2 = bn_rand_range_gt_one(grp->q)) == NULL)
+		fatal("%s: bn_rand_range_gt_one", __func__);
+
+	/*
+	 * client: g_x1 = g^x1 mod p / server: g_x3 = g^x3 mod p
+	 * client: g_x2 = g^x2 mod p / server: g_x4 = g^x4 mod p
+	 */
+	if ((*g_priv1 = BN_new()) == NULL ||
+	    (*g_priv2 = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+	if (BN_mod_exp(*g_priv1, grp->g, *priv1, grp->p, bn_ctx) == -1)
+		fatal("%s: BN_mod_exp", __func__);
+	if (BN_mod_exp(*g_priv2, grp->g, *priv2, grp->p, bn_ctx) == -1)
+		fatal("%s: BN_mod_exp", __func__);
+
+	/* Generate proofs for holding x1/x3 and x2/x4 */
+	if (schnorr_sign(grp->p, grp->q, grp->g,
+	    *priv1, *g_priv1, *id, *id_len,
+	    priv1_proof, priv1_proof_len) != 0)
+		fatal("%s: schnorr_sign", __func__);
+	if (schnorr_sign(grp->p, grp->q, grp->g,
+	    *priv2, *g_priv2, *id, *id_len,
+	    priv2_proof, priv2_proof_len) != 0)
+		fatal("%s: schnorr_sign", __func__);
+
+	BN_CTX_free(bn_ctx);
+}
+
+/* Shared parts of step 2 exchange calculation */
+void
+jpake_step2(struct jpake_group *grp, BIGNUM *s,
+    BIGNUM *mypub1, BIGNUM *theirpub1, BIGNUM *theirpub2, BIGNUM *mypriv2,
+    const u_char *theirid, u_int theirid_len,
+    const u_char *myid, u_int myid_len,
+    const u_char *theirpub1_proof, u_int theirpub1_proof_len,
+    const u_char *theirpub2_proof, u_int theirpub2_proof_len,
+    BIGNUM **newpub,
+    u_char **newpub_exponent_proof, u_int *newpub_exponent_proof_len)
+{
+	BN_CTX *bn_ctx;
+	BIGNUM *tmp, *exponent;
+
+	/* Validate peer's step 1 values */
+	if (BN_cmp(theirpub1, BN_value_one()) <= 0)
+		fatal("%s: theirpub1 <= 1", __func__);
+	if (BN_cmp(theirpub2, BN_value_one()) <= 0)
+		fatal("%s: theirpub2 <= 1", __func__);
+
+	if (schnorr_verify(grp->p, grp->q, grp->g, theirpub1,
+	    theirid, theirid_len, theirpub1_proof, theirpub1_proof_len) != 1)
+		fatal("%s: schnorr_verify theirpub1 failed", __func__);
+	if (schnorr_verify(grp->p, grp->q, grp->g, theirpub2,
+	    theirid, theirid_len, theirpub2_proof, theirpub2_proof_len) != 1)
+		fatal("%s: schnorr_verify theirpub2 failed", __func__);
+
+	if ((bn_ctx = BN_CTX_new()) == NULL)
+		fatal("%s: BN_CTX_new", __func__);
+
+	if ((*newpub = BN_new()) == NULL ||
+	    (tmp = BN_new()) == NULL ||
+	    (exponent = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	/*
+	 * client: exponent = x2 * s mod p
+	 * server: exponent = x4 * s mod p
+	 */
+	if (BN_mod_mul(exponent, mypriv2, s, grp->q, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (exponent = mypriv2 * s mod p)",
+		    __func__);
+
+	/*
+	 * client: tmp = g^(x1 + x3 + x4) mod p
+	 * server: tmp = g^(x1 + x2 + x3) mod p
+	 */
+	if (BN_mod_mul(tmp, mypub1, theirpub1, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (tmp = mypub1 * theirpub1 mod p)",
+		    __func__);
+	if (BN_mod_mul(tmp, tmp, theirpub2, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (tmp = tmp * theirpub2 mod p)", __func__);
+
+	/*
+	 * client: a = tmp^exponent = g^((x1+x3+x4) * x2 * s) mod p
+	 * server: b = tmp^exponent = g^((x1+x2+x3) * x4 * s) mod p
+	 */
+	if (BN_mod_exp(*newpub, tmp, exponent, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (newpub = tmp^exponent mod p)", __func__);
+
+	JPAKE_DEBUG_BN((tmp, "%s: tmp = ", __func__));
+	JPAKE_DEBUG_BN((exponent, "%s: exponent = ", __func__));
+
+	/* Note the generator here is 'tmp', not g */
+	if (schnorr_sign(grp->p, grp->q, tmp, exponent, *newpub,
+	    myid, myid_len,
+	    newpub_exponent_proof, newpub_exponent_proof_len) != 0)
+		fatal("%s: schnorr_sign newpub", __func__);
+
+	BN_clear_free(tmp); /* XXX stash for later use? */
+	BN_clear_free(exponent); /* XXX stash for later use? (yes, in conf) */
+
+	BN_CTX_free(bn_ctx);
+}
+
+/* Confirmation hash calculation */
+void
+jpake_confirm_hash(const BIGNUM *k,
+    const u_char *endpoint_id, u_int endpoint_id_len,
+    const u_char *sess_id, u_int sess_id_len,
+    u_char **confirm_hash, u_int *confirm_hash_len)
+{
+	Buffer b;
+
+	/*
+	 * Calculate confirmation proof:
+	 *     client: H(k || client_id || session_id)
+	 *     server: H(k || server_id || session_id)
+	 */
+	buffer_init(&b);
+	buffer_put_bignum2(&b, k);
+	buffer_put_string(&b, endpoint_id, endpoint_id_len);
+	buffer_put_string(&b, sess_id, sess_id_len);
+	if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(),
+	    confirm_hash, confirm_hash_len) != 0)
+		fatal("%s: hash_buffer", __func__);
+	buffer_free(&b);
+}
+
+/* Shared parts of key derivation and confirmation calculation */
+void
+jpake_key_confirm(struct jpake_group *grp, BIGNUM *s, BIGNUM *step2_val,
+    BIGNUM *mypriv2, BIGNUM *mypub1, BIGNUM *mypub2,
+    BIGNUM *theirpub1, BIGNUM *theirpub2,
+    const u_char *my_id, u_int my_id_len,
+    const u_char *their_id, u_int their_id_len,
+    const u_char *sess_id, u_int sess_id_len,
+    const u_char *theirpriv2_s_proof, u_int theirpriv2_s_proof_len,
+    BIGNUM **k,
+    u_char **confirm_hash, u_int *confirm_hash_len)
+{
+	BN_CTX *bn_ctx;
+	BIGNUM *tmp;
+
+	if ((bn_ctx = BN_CTX_new()) == NULL)
+		fatal("%s: BN_CTX_new", __func__);
+	if ((tmp = BN_new()) == NULL ||
+	    (*k = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	/* Validate step 2 values */
+	if (BN_cmp(step2_val, BN_value_one()) <= 0)
+		fatal("%s: step2_val <= 1", __func__);
+
+	/*
+	 * theirpriv2_s_proof is calculated with a different generator:
+	 * tmp = g^(mypriv1+mypriv2+theirpub1) = g^mypub1*g^mypub2*g^theirpub1
+	 * Calculate it here so we can check the signature.
+	 */
+	if (BN_mod_mul(tmp, mypub1, mypub2, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (tmp = mypub1 * mypub2 mod p)", __func__);
+	if (BN_mod_mul(tmp, tmp, theirpub1, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (tmp = tmp * theirpub1 mod p)", __func__);
+
+	JPAKE_DEBUG_BN((tmp, "%s: tmp = ", __func__));
+
+	if (schnorr_verify(grp->p, grp->q, tmp, step2_val, 
+	    their_id, their_id_len,
+	    theirpriv2_s_proof, theirpriv2_s_proof_len) != 1)
+		fatal("%s: schnorr_verify theirpriv2_s_proof failed", __func__);
+
+	/*
+	 * Derive shared key:
+	 *     client: k = (b / g^(x2*x4*s))^x2 = g^((x1+x3)*x2*x4*s)
+	 *     server: k = (a / g^(x2*x4*s))^x4 = g^((x1+x3)*x2*x4*s)
+	 *
+	 * Computed as:
+	 *     client: k = (g_x4^(q - (x2 * s)) * b)^x2 mod p
+	 *     server: k = (g_x2^(q - (x4 * s)) * b)^x4 mod p
+	 */
+	if (BN_mul(tmp, mypriv2, s, bn_ctx) != 1)
+		fatal("%s: BN_mul (tmp = mypriv2 * s)", __func__);
+	if (BN_mod_sub(tmp, grp->q, tmp, grp->q, bn_ctx) != 1)
+		fatal("%s: BN_mod_sub (tmp = q - tmp mod q)", __func__);
+	if (BN_mod_exp(tmp, theirpub2, tmp, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_exp (tmp = theirpub2^tmp) mod p", __func__);
+	if (BN_mod_mul(tmp, tmp, step2_val, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_mul (tmp = tmp * step2_val) mod p", __func__);
+	if (BN_mod_exp(*k, tmp, mypriv2, grp->p, bn_ctx) != 1)
+		fatal("%s: BN_mod_exp (k = tmp^mypriv2) mod p", __func__);
+	
+	BN_CTX_free(bn_ctx);
+	BN_clear_free(tmp);
+
+	jpake_confirm_hash(*k, my_id, my_id_len, sess_id, sess_id_len,
+	    confirm_hash, confirm_hash_len);
+}
+
+/*
+ * Calculate and check confirmation hash from peer. Returns 1 on success
+ * 0 on failure/mismatch.
+ */
+int
+jpake_check_confirm(const BIGNUM *k,
+    const u_char *peer_id, u_int peer_id_len,
+    const u_char *sess_id, u_int sess_id_len,
+    const u_char *peer_confirm_hash, u_int peer_confirm_hash_len)
+{
+	u_char *expected_confirm_hash;
+	u_int expected_confirm_hash_len;
+	int success = 0;
+
+	/* Calculate and verify expected confirmation hash */
+	jpake_confirm_hash(k, peer_id, peer_id_len, sess_id, sess_id_len,
+	    &expected_confirm_hash, &expected_confirm_hash_len);
+
+	JPAKE_DEBUG_BUF((expected_confirm_hash, expected_confirm_hash_len,
+	    "%s: expected confirm hash", __func__));
+	JPAKE_DEBUG_BUF((peer_confirm_hash, peer_confirm_hash_len,
+	    "%s: received confirm hash", __func__));
+
+	if (peer_confirm_hash_len != expected_confirm_hash_len)
+		error("%s: confirmation length mismatch (my %u them %u)",
+		    __func__, expected_confirm_hash_len, peer_confirm_hash_len);
+	else if (memcmp(peer_confirm_hash, expected_confirm_hash,
+	    expected_confirm_hash_len) == 0)
+		success = 1;
+	bzero(expected_confirm_hash, expected_confirm_hash_len);
+	xfree(expected_confirm_hash);
+	debug3("%s: success = %d", __func__, success);
+	return success;
+}
+
+/* XXX main() function with tests */
+
+#endif /* JPAKE */
+
diff --git a/jpake.h b/jpake.h
new file mode 100644
index 00000000..a3d800cd
--- /dev/null
+++ b/jpake.h
@@ -0,0 +1,134 @@
+/* $OpenBSD: jpake.h,v 1.1 2008/11/04 08:22:13 djm Exp $ */
+/*
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef JPAKE_H
+#define JPAKE_H
+
+#include <sys/types.h>
+
+#include <openssl/bn.h>
+
+/* Set JPAKE_DEBUG in CFLAGS for privacy-violating debugging */
+#ifndef JPAKE_DEBUG
+# define JPAKE_DEBUG_BN(a)
+# define JPAKE_DEBUG_BUF(a)
+# define JPAKE_DEBUG_CTX(a)
+#else
+# define JPAKE_DEBUG_BN(a)	jpake_debug3_bn a
+# define JPAKE_DEBUG_BUF(a)	jpake_debug3_buf a
+# define JPAKE_DEBUG_CTX(a)	jpake_dump a
+#endif /* SCHNORR_DEBUG */
+
+struct jpake_group {
+	BIGNUM *p, *q, *g;
+};
+
+#define KZP_ID_LEN	16	/* Length of client and server IDs */
+
+struct jpake_ctx {
+	/* Parameters */
+	struct jpake_group *grp;
+
+	/* Private values shared by client and server */
+	BIGNUM *s;			/* Secret (salted, crypted password) */
+	BIGNUM *k;			/* Derived key */
+
+	/* Client private values (NULL for server) */
+	BIGNUM *x1;			/* random in Zq */
+	BIGNUM *x2;			/* random in Z*q */
+
+	/* Server private values (NULL for server) */
+	BIGNUM *x3;			/* random in Zq */
+	BIGNUM *x4;			/* random in Z*q */
+
+	/* Step 1: C->S */
+	u_char *client_id;		/* Anti-replay nonce */
+	u_int client_id_len;
+	BIGNUM *g_x1;			/* g^x1 */
+	BIGNUM *g_x2;			/* g^x2 */
+
+	/* Step 1: S->C */
+	u_char *server_id;		/* Anti-replay nonce */
+	u_int server_id_len;
+	BIGNUM *g_x3;			/* g^x3 */
+	BIGNUM *g_x4;			/* g^x4 */
+
+	/* Step 2: C->S */
+	BIGNUM *a;			/* g^((x1+x3+x4)*x2*s) */
+
+	/* Step 2: S->C */
+	BIGNUM *b;			/* g^((x1+x2+x3)*x4*s) */
+
+	/* Confirmation: C->S */
+	u_char *h_k_cid_sessid;		/* H(k || client_id || session_id) */
+	u_int h_k_cid_sessid_len;
+
+	/* Confirmation: S->C */
+	u_char *h_k_sid_sessid;		/* H(k || server_id || session_id) */
+	u_int h_k_sid_sessid_len;
+};
+
+/* jpake.c */
+struct jpake_group *jpake_default_group(void);
+BIGNUM *bn_rand_range_gt_one(const BIGNUM *high);
+int hash_buffer(const u_char *, u_int, const EVP_MD *, u_char **, u_int *);
+void jpake_debug3_bn(const BIGNUM *, const char *, ...)
+    __attribute__((__nonnull__ (2)))
+    __attribute__((format(printf, 2, 3)));
+void jpake_debug3_buf(const u_char *, u_int, const char *, ...)
+    __attribute__((__nonnull__ (3)))
+    __attribute__((format(printf, 3, 4)));
+void jpake_dump(struct jpake_ctx *, const char *, ...)
+    __attribute__((__nonnull__ (2)))
+    __attribute__((format(printf, 2, 3)));
+struct jpake_ctx *jpake_new(void);
+void jpake_free(struct jpake_ctx *);
+
+void jpake_step1(struct jpake_group *, u_char **, u_int *,
+    BIGNUM **, BIGNUM **, BIGNUM **, BIGNUM **,
+    u_char **, u_int *, u_char **, u_int *);
+
+void jpake_step2(struct jpake_group *, BIGNUM *,
+    BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *,
+    const u_char *, u_int, const u_char *, u_int,
+    const u_char *, u_int, const u_char *, u_int,
+    BIGNUM **, u_char **, u_int *);
+
+void jpake_confirm_hash(const BIGNUM *,
+    const u_char *, u_int,
+    const u_char *, u_int,
+    u_char **, u_int *);
+
+void jpake_key_confirm(struct jpake_group *, BIGNUM *, BIGNUM *,
+    BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *,
+    const u_char *, u_int, const u_char *, u_int,
+    const u_char *, u_int, const u_char *, u_int,
+    BIGNUM **, u_char **, u_int *);
+
+int jpake_check_confirm(const BIGNUM *, const u_char *, u_int,
+    const u_char *, u_int, const u_char *, u_int);
+
+/* schnorr.c */
+int schnorr_sign(const BIGNUM *, const BIGNUM *, const BIGNUM *,
+    const BIGNUM *, const BIGNUM *, const u_char *, u_int ,
+    u_char **, u_int *);
+int schnorr_verify(const BIGNUM *, const BIGNUM *, const BIGNUM *, 
+    const BIGNUM *, const u_char *, u_int,
+    const u_char *, u_int);
+
+#endif /* JPAKE_H */
+
diff --git a/monitor.c b/monitor.c
index 73cf6bc9..39deedc8 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.99 2008/07/10 18:08:11 markus Exp $ */
+/* $OpenBSD: monitor.c,v 1.100 2008/11/04 08:22:13 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -87,6 +87,7 @@
 #include "misc.h"
 #include "compat.h"
 #include "ssh2.h"
+#include "jpake.h"
 
 #ifdef GSSAPI
 static Gssctxt *gsscontext = NULL;
@@ -149,6 +150,11 @@ int mm_answer_rsa_challenge(int, Buffer *);
 int mm_answer_rsa_response(int, Buffer *);
 int mm_answer_sesskey(int, Buffer *);
 int mm_answer_sessid(int, Buffer *);
+int mm_answer_jpake_get_pwdata(int, Buffer *);
+int mm_answer_jpake_step1(int, Buffer *);
+int mm_answer_jpake_step2(int, Buffer *);
+int mm_answer_jpake_key_confirm(int, Buffer *);
+int mm_answer_jpake_check_confirm(int, Buffer *);
 
 #ifdef USE_PAM
 int mm_answer_pam_start(int, Buffer *);
@@ -234,6 +240,13 @@ struct mon_table mon_dispatch_proto20[] = {
     {MONITOR_REQ_GSSUSEROK, MON_AUTH, mm_answer_gss_userok},
     {MONITOR_REQ_GSSCHECKMIC, MON_ISAUTH, mm_answer_gss_checkmic},
 #endif
+#ifdef JPAKE
+    {MONITOR_REQ_JPAKE_GET_PWDATA, MON_ONCE, mm_answer_jpake_get_pwdata},
+    {MONITOR_REQ_JPAKE_STEP1, MON_ISAUTH, mm_answer_jpake_step1},
+    {MONITOR_REQ_JPAKE_STEP2, MON_ONCE, mm_answer_jpake_step2},
+    {MONITOR_REQ_JPAKE_KEY_CONFIRM, MON_ONCE, mm_answer_jpake_key_confirm},
+    {MONITOR_REQ_JPAKE_CHECK_CONFIRM, MON_AUTH, mm_answer_jpake_check_confirm},
+#endif
     {0, 0, NULL}
 };
 
@@ -379,6 +392,15 @@ monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor)
 			if (!authenticated)
 				authctxt->failures++;
 		}
+#ifdef JPAKE
+		/* Cleanup JPAKE context after authentication */
+		if (ent->flags & MON_AUTHDECIDE) {
+			if (authctxt->jpake_ctx != NULL) {
+				jpake_free(authctxt->jpake_ctx);
+				authctxt->jpake_ctx = NULL;
+			}
+		}
+#endif
 	}
 
 	if (!authctxt->valid)
@@ -1969,3 +1991,206 @@ mm_answer_gss_userok(int sock, Buffer *m)
 	return (authenticated);
 }
 #endif /* GSSAPI */
+
+#ifdef JPAKE
+int
+mm_answer_jpake_step1(int sock, Buffer *m)
+{
+	struct jpake_ctx *pctx;
+	u_char *x3_proof, *x4_proof;
+	u_int x3_proof_len, x4_proof_len;
+
+	if (!options.zero_knowledge_password_authentication)
+		fatal("zero_knowledge_password_authentication disabled");
+
+	if (authctxt->jpake_ctx != NULL)
+		fatal("%s: authctxt->jpake_ctx already set (%p)",
+		    __func__, authctxt->jpake_ctx);
+	authctxt->jpake_ctx = pctx = jpake_new();
+
+	jpake_step1(pctx->grp,
+	    &pctx->server_id, &pctx->server_id_len,
+	    &pctx->x3, &pctx->x4, &pctx->g_x3, &pctx->g_x4,
+	    &x3_proof, &x3_proof_len,
+	    &x4_proof, &x4_proof_len);
+
+	JPAKE_DEBUG_CTX((pctx, "step1 done in %s", __func__));
+
+	buffer_clear(m);
+
+	buffer_put_string(m, pctx->server_id, pctx->server_id_len);
+	buffer_put_bignum2(m, pctx->g_x3);
+	buffer_put_bignum2(m, pctx->g_x4);
+	buffer_put_string(m, x3_proof, x3_proof_len);
+	buffer_put_string(m, x4_proof, x4_proof_len);
+
+	debug3("%s: sending step1", __func__);
+	mm_request_send(sock, MONITOR_ANS_JPAKE_STEP1, m);
+
+	bzero(x3_proof, x3_proof_len);
+	bzero(x4_proof, x4_proof_len);
+	xfree(x3_proof);
+	xfree(x4_proof);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_GET_PWDATA, 1);
+	monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_STEP1, 0);
+
+	return 0;
+}
+
+int
+mm_answer_jpake_get_pwdata(int sock, Buffer *m)
+{
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	char *hash_scheme, *salt;
+
+	if (pctx == NULL)
+		fatal("%s: pctx == NULL", __func__);
+
+	auth2_jpake_get_pwdata(authctxt, &pctx->s, &hash_scheme, &salt);
+
+	buffer_clear(m);
+	/* pctx->s is sensitive, not returned to slave */
+	buffer_put_cstring(m, hash_scheme);
+	buffer_put_cstring(m, salt);
+
+	debug3("%s: sending pwdata", __func__);
+	mm_request_send(sock, MONITOR_ANS_JPAKE_GET_PWDATA, m);
+
+	bzero(hash_scheme, strlen(hash_scheme));
+	bzero(salt, strlen(salt));
+	xfree(hash_scheme);
+	xfree(salt);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_STEP2, 1);
+
+	return 0;
+}
+
+int
+mm_answer_jpake_step2(int sock, Buffer *m)
+{
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	u_char *x1_proof, *x2_proof, *x4_s_proof;
+	u_int x1_proof_len, x2_proof_len, x4_s_proof_len;
+
+	if (pctx == NULL)
+		fatal("%s: pctx == NULL", __func__);
+
+	if ((pctx->g_x1 = BN_new()) == NULL ||
+	    (pctx->g_x2 = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+	buffer_get_bignum2(m, pctx->g_x1);
+	buffer_get_bignum2(m, pctx->g_x2);
+	pctx->client_id = buffer_get_string(m, &pctx->client_id_len);
+	x1_proof = buffer_get_string(m, &x1_proof_len);
+	x2_proof = buffer_get_string(m, &x2_proof_len);
+
+	jpake_step2(pctx->grp, pctx->s, pctx->g_x3,
+	    pctx->g_x1, pctx->g_x2, pctx->x4,
+	    pctx->client_id, pctx->client_id_len,
+	    pctx->server_id, pctx->server_id_len,
+	    x1_proof, x1_proof_len,
+	    x2_proof, x2_proof_len,
+	    &pctx->b,
+	    &x4_s_proof, &x4_s_proof_len);
+
+	JPAKE_DEBUG_CTX((pctx, "step2 done in %s", __func__));
+
+	bzero(x1_proof, x1_proof_len);
+	bzero(x2_proof, x2_proof_len);
+	xfree(x1_proof);
+	xfree(x2_proof);
+
+	buffer_clear(m);
+
+	buffer_put_bignum2(m, pctx->b);
+	buffer_put_string(m, x4_s_proof, x4_s_proof_len);
+
+	debug3("%s: sending step2", __func__);
+	mm_request_send(sock, MONITOR_ANS_JPAKE_STEP2, m);
+
+	bzero(x4_s_proof, x4_s_proof_len);
+	xfree(x4_s_proof);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_KEY_CONFIRM, 1);
+
+	return 0;
+}
+
+int
+mm_answer_jpake_key_confirm(int sock, Buffer *m)
+{
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+	u_char *x2_s_proof;
+	u_int x2_s_proof_len;
+
+	if (pctx == NULL)
+		fatal("%s: pctx == NULL", __func__);
+
+	if ((pctx->a = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+	buffer_get_bignum2(m, pctx->a);
+	x2_s_proof = buffer_get_string(m, &x2_s_proof_len);
+
+	jpake_key_confirm(pctx->grp, pctx->s, pctx->a,
+	    pctx->x4, pctx->g_x3, pctx->g_x4, pctx->g_x1, pctx->g_x2,
+	    pctx->server_id, pctx->server_id_len,
+	    pctx->client_id, pctx->client_id_len,
+	    session_id2, session_id2_len,
+	    x2_s_proof, x2_s_proof_len,
+	    &pctx->k,
+	    &pctx->h_k_sid_sessid, &pctx->h_k_sid_sessid_len);
+
+	JPAKE_DEBUG_CTX((pctx, "key_confirm done in %s", __func__));
+
+	bzero(x2_s_proof, x2_s_proof_len);
+	buffer_clear(m);
+
+	/* pctx->k is sensitive, not sent */
+	buffer_put_string(m, pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len);
+
+	debug3("%s: sending confirmation hash", __func__);
+	mm_request_send(sock, MONITOR_ANS_JPAKE_KEY_CONFIRM, m);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_CHECK_CONFIRM, 1);
+
+	return 0;
+}
+
+int
+mm_answer_jpake_check_confirm(int sock, Buffer *m)
+{
+	int authenticated = 0;
+	u_char *peer_confirm_hash;
+	u_int peer_confirm_hash_len;
+	struct jpake_ctx *pctx = authctxt->jpake_ctx;
+
+	if (pctx == NULL)
+		fatal("%s: pctx == NULL", __func__);
+
+	peer_confirm_hash = buffer_get_string(m, &peer_confirm_hash_len);
+
+	authenticated = jpake_check_confirm(pctx->k,
+	    pctx->client_id, pctx->client_id_len,
+	    session_id2, session_id2_len,
+	    peer_confirm_hash, peer_confirm_hash_len) && authctxt->valid;
+
+	JPAKE_DEBUG_CTX((pctx, "check_confirm done in %s", __func__));
+
+	bzero(peer_confirm_hash, peer_confirm_hash_len);
+	xfree(peer_confirm_hash);
+
+	buffer_clear(m);
+	buffer_put_int(m, authenticated);
+
+	debug3("%s: sending result %d", __func__, authenticated);
+	mm_request_send(sock, MONITOR_ANS_JPAKE_CHECK_CONFIRM, m);
+
+	monitor_permit(mon_dispatch, MONITOR_REQ_JPAKE_STEP1, 1);
+
+	auth_method = "jpake-01@openssh.com";
+	return authenticated;
+}
+
+#endif /* JPAKE */
diff --git a/monitor.h b/monitor.h
index 464009ad..a8a2c0c1 100644
--- a/monitor.h
+++ b/monitor.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.h,v 1.14 2006/03/25 22:22:43 djm Exp $ */
+/* $OpenBSD: monitor.h,v 1.15 2008/11/04 08:22:13 djm Exp $ */
 
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@@ -60,7 +60,12 @@ enum monitor_reqtype {
 	MONITOR_REQ_PAM_RESPOND, MONITOR_ANS_PAM_RESPOND,
 	MONITOR_REQ_PAM_FREE_CTX, MONITOR_ANS_PAM_FREE_CTX,
 	MONITOR_REQ_AUDIT_EVENT, MONITOR_REQ_AUDIT_COMMAND,
-	MONITOR_REQ_TERM
+	MONITOR_REQ_TERM,
+	MONITOR_REQ_JPAKE_STEP1, MONITOR_ANS_JPAKE_STEP1,
+	MONITOR_REQ_JPAKE_GET_PWDATA, MONITOR_ANS_JPAKE_GET_PWDATA,
+	MONITOR_REQ_JPAKE_STEP2, MONITOR_ANS_JPAKE_STEP2,
+	MONITOR_REQ_JPAKE_KEY_CONFIRM, MONITOR_ANS_JPAKE_KEY_CONFIRM,
+	MONITOR_REQ_JPAKE_CHECK_CONFIRM, MONITOR_ANS_JPAKE_CHECK_CONFIRM,
 };
 
 struct mm_master;
diff --git a/monitor_wrap.c b/monitor_wrap.c
index 40463d07..0986fc51 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.63 2008/07/10 18:08:11 markus Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.64 2008/11/04 08:22:13 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -40,6 +40,7 @@
 
 #include <openssl/bn.h>
 #include <openssl/dh.h>
+#include <openssl/evp.h>
 
 #include "openbsd-compat/sys-queue.h"
 #include "xmalloc.h"
@@ -70,7 +71,7 @@
 #include "atomicio.h"
 #include "monitor_fdpass.h"
 #include "misc.h"
-#include "servconf.h"
+#include "jpake.h"
 
 #include "channels.h"
 #include "session.h"
@@ -1256,3 +1257,165 @@ mm_ssh_gssapi_userok(char *user)
 	return (authenticated);
 }
 #endif /* GSSAPI */
+
+#ifdef JPAKE
+void
+mm_auth2_jpake_get_pwdata(Authctxt *authctxt, BIGNUM **s,
+    char **hash_scheme, char **salt)
+{
+	Buffer m;
+
+	debug3("%s entering", __func__);
+
+	buffer_init(&m);
+	mm_request_send(pmonitor->m_recvfd,
+	    MONITOR_REQ_JPAKE_GET_PWDATA, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_JPAKE_GET_PWDATA", __func__);
+	mm_request_receive_expect(pmonitor->m_recvfd,
+	    MONITOR_ANS_JPAKE_GET_PWDATA, &m);
+
+	*hash_scheme = buffer_get_string(&m, NULL);
+	*salt = buffer_get_string(&m, NULL);
+
+	buffer_free(&m);
+}
+
+void
+mm_jpake_step1(struct jpake_group *grp,
+    u_char **id, u_int *id_len,
+    BIGNUM **priv1, BIGNUM **priv2, BIGNUM **g_priv1, BIGNUM **g_priv2,
+    u_char **priv1_proof, u_int *priv1_proof_len,
+    u_char **priv2_proof, u_int *priv2_proof_len)
+{
+	Buffer m;
+
+	debug3("%s entering", __func__);
+
+	buffer_init(&m);
+	mm_request_send(pmonitor->m_recvfd,
+	    MONITOR_REQ_JPAKE_STEP1, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_JPAKE_STEP1", __func__);
+	mm_request_receive_expect(pmonitor->m_recvfd,
+	    MONITOR_ANS_JPAKE_STEP1, &m);
+
+	if ((*priv1 = BN_new()) == NULL ||
+	    (*priv2 = BN_new()) == NULL ||
+	    (*g_priv1 = BN_new()) == NULL ||
+	    (*g_priv2 = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	*id = buffer_get_string(&m, id_len);
+	/* priv1 and priv2 are, well, private */
+	buffer_get_bignum2(&m, *g_priv1);
+	buffer_get_bignum2(&m, *g_priv2);
+	*priv1_proof = buffer_get_string(&m, priv1_proof_len);
+	*priv2_proof = buffer_get_string(&m, priv2_proof_len);
+
+	buffer_free(&m);
+}
+
+void
+mm_jpake_step2(struct jpake_group *grp, BIGNUM *s,
+    BIGNUM *mypub1, BIGNUM *theirpub1, BIGNUM *theirpub2, BIGNUM *mypriv2,
+    const u_char *theirid, u_int theirid_len,
+    const u_char *myid, u_int myid_len,
+    const u_char *theirpub1_proof, u_int theirpub1_proof_len,
+    const u_char *theirpub2_proof, u_int theirpub2_proof_len,
+    BIGNUM **newpub,
+    u_char **newpub_exponent_proof, u_int *newpub_exponent_proof_len)
+{
+	Buffer m;
+
+	debug3("%s entering", __func__);
+
+	buffer_init(&m);
+	/* monitor already has all bignums except theirpub1, theirpub2 */
+	buffer_put_bignum2(&m, theirpub1);
+	buffer_put_bignum2(&m, theirpub2);
+	/* monitor already knows our id */
+	buffer_put_string(&m, theirid, theirid_len);
+	buffer_put_string(&m, theirpub1_proof, theirpub1_proof_len);
+	buffer_put_string(&m, theirpub2_proof, theirpub2_proof_len);
+
+	mm_request_send(pmonitor->m_recvfd,
+	    MONITOR_REQ_JPAKE_STEP2, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_JPAKE_STEP2", __func__);
+	mm_request_receive_expect(pmonitor->m_recvfd,
+	    MONITOR_ANS_JPAKE_STEP2, &m);
+
+	if ((*newpub = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	buffer_get_bignum2(&m, *newpub);
+	*newpub_exponent_proof = buffer_get_string(&m,
+	    newpub_exponent_proof_len);
+
+	buffer_free(&m);
+}
+
+void
+mm_jpake_key_confirm(struct jpake_group *grp, BIGNUM *s, BIGNUM *step2_val,
+    BIGNUM *mypriv2, BIGNUM *mypub1, BIGNUM *mypub2,
+    BIGNUM *theirpub1, BIGNUM *theirpub2,
+    const u_char *my_id, u_int my_id_len,
+    const u_char *their_id, u_int their_id_len,
+    const u_char *sess_id, u_int sess_id_len,
+    const u_char *theirpriv2_s_proof, u_int theirpriv2_s_proof_len,
+    BIGNUM **k,
+    u_char **confirm_hash, u_int *confirm_hash_len)
+{
+	Buffer m;
+
+	debug3("%s entering", __func__);
+
+	buffer_init(&m);
+	/* monitor already has all bignums except step2_val */
+	buffer_put_bignum2(&m, step2_val);
+	/* monitor already knows all the ids */
+	buffer_put_string(&m, theirpriv2_s_proof, theirpriv2_s_proof_len);
+
+	mm_request_send(pmonitor->m_recvfd,
+	    MONITOR_REQ_JPAKE_KEY_CONFIRM, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_JPAKE_KEY_CONFIRM", __func__);
+	mm_request_receive_expect(pmonitor->m_recvfd,
+	    MONITOR_ANS_JPAKE_KEY_CONFIRM, &m);
+
+	/* 'k' is sensitive and stays in the monitor */
+	*confirm_hash = buffer_get_string(&m, confirm_hash_len);
+
+	buffer_free(&m);
+}
+
+int
+mm_jpake_check_confirm(const BIGNUM *k,
+    const u_char *peer_id, u_int peer_id_len,
+    const u_char *sess_id, u_int sess_id_len,
+    const u_char *peer_confirm_hash, u_int peer_confirm_hash_len)
+{
+	Buffer m;
+	int success = 0;
+
+	debug3("%s entering", __func__);
+
+	buffer_init(&m);
+	/* k is dummy in slave, ignored */
+	/* monitor knows all the ids */
+	buffer_put_string(&m, peer_confirm_hash, peer_confirm_hash_len);
+	mm_request_send(pmonitor->m_recvfd,
+	    MONITOR_REQ_JPAKE_CHECK_CONFIRM, &m);
+
+	debug3("%s: waiting for MONITOR_ANS_JPAKE_CHECK_CONFIRM", __func__);
+	mm_request_receive_expect(pmonitor->m_recvfd,
+	    MONITOR_ANS_JPAKE_CHECK_CONFIRM, &m);
+
+	success = buffer_get_int(&m);
+	buffer_free(&m);
+
+	debug3("%s: success = %d", __func__, success);
+	return success;
+}
+#endif /* JPAKE */
diff --git a/monitor_wrap.h b/monitor_wrap.h
index 329189c2..55c4b99f 100644
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.h,v 1.20 2006/08/03 03:34:42 deraadt Exp $ */
+/* $OpenBSD: monitor_wrap.h,v 1.21 2008/11/04 08:22:13 djm Exp $ */
 
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
@@ -101,6 +101,26 @@ int mm_bsdauth_respond(void *, u_int, char **);
 int mm_skey_query(void *, char **, char **, u_int *, char ***, u_int **);
 int mm_skey_respond(void *, u_int, char **);
 
+/* jpake */
+struct jpake_group;
+void mm_auth2_jpake_get_pwdata(struct Authctxt *, BIGNUM **, char **, char **);
+void mm_jpake_step1(struct jpake_group *, u_char **, u_int *,
+    BIGNUM **, BIGNUM **, BIGNUM **, BIGNUM **,
+    u_char **, u_int *, u_char **, u_int *);
+void mm_jpake_step2(struct jpake_group *, BIGNUM *,
+    BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *,
+    const u_char *, u_int, const u_char *, u_int,
+    const u_char *, u_int, const u_char *, u_int,
+    BIGNUM **, u_char **, u_int *);
+void mm_jpake_key_confirm(struct jpake_group *, BIGNUM *, BIGNUM *,
+    BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *, BIGNUM *,
+    const u_char *, u_int, const u_char *, u_int,
+    const u_char *, u_int, const u_char *, u_int,
+    BIGNUM **, u_char **, u_int *);
+int mm_jpake_check_confirm(const BIGNUM *,
+    const u_char *, u_int, const u_char *, u_int, const u_char *, u_int);
+
+
 /* zlib allocation hooks */
 
 void *mm_zalloc(struct mm_master *, u_int, u_int);
diff --git a/readconf.c b/readconf.c
index 7f7bbfee..ba70d9da 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.170 2008/11/03 02:44:41 stevesk Exp $ */
+/* $OpenBSD: readconf.c,v 1.171 2008/11/04 08:22:13 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -130,7 +130,7 @@ typedef enum {
 	oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly,
 	oSendEnv, oControlPath, oControlMaster, oHashKnownHosts,
 	oTunnel, oTunnelDevice, oLocalCommand, oPermitLocalCommand,
-	oVisualHostKey,
+	oVisualHostKey, oZeroKnowledgePasswordAuthentication,
 	oDeprecated, oUnsupported
 } OpCodes;
 
@@ -228,6 +228,13 @@ static struct {
 	{ "localcommand", oLocalCommand },
 	{ "permitlocalcommand", oPermitLocalCommand },
 	{ "visualhostkey", oVisualHostKey },
+#ifdef JPAKE
+	{ "zeroknowledgepasswordauthentication",
+	    oZeroKnowledgePasswordAuthentication },
+#else
+	{ "zeroknowledgepasswordauthentication", oUnsupported },
+#endif
+
 	{ NULL, oBadOption }
 };
 
@@ -412,6 +419,10 @@ parse_flag:
 		intptr = &options->password_authentication;
 		goto parse_flag;
 
+	case oZeroKnowledgePasswordAuthentication:
+		intptr = &options->zero_knowledge_password_authentication;
+		goto parse_flag;
+
 	case oKbdInteractiveAuthentication:
 		intptr = &options->kbd_interactive_authentication;
 		goto parse_flag;
@@ -1054,6 +1065,7 @@ initialize_options(Options * options)
 	options->local_command = NULL;
 	options->permit_local_command = -1;
 	options->visual_host_key = -1;
+	options->zero_knowledge_password_authentication = -1;
 }
 
 /*
@@ -1190,6 +1202,8 @@ fill_default_options(Options * options)
 		options->permit_local_command = 0;
 	if (options->visual_host_key == -1)
 		options->visual_host_key = 0;
+	if (options->zero_knowledge_password_authentication == -1)
+		options->zero_knowledge_password_authentication = 0;
 	/* options->local_command should not be set by default */
 	/* options->proxy_command should not be set by default */
 	/* options->user will be set in the main program if appropriate */
diff --git a/readconf.h b/readconf.h
index c1387a89..c9e5f6a4 100644
--- a/readconf.h
+++ b/readconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.h,v 1.75 2008/11/01 17:40:33 stevesk Exp $ */
+/* $OpenBSD: readconf.h,v 1.76 2008/11/04 08:22:13 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -49,6 +49,7 @@ typedef struct {
 						 * authentication. */
 	int     kbd_interactive_authentication; /* Try keyboard-interactive auth. */
 	char	*kbd_interactive_devices; /* Keyboard-interactive auth devices. */
+	int     zero_knowledge_password_authentication;	/* Try jpake */
 	int     batch_mode;	/* Batch mode: do not ask for passwords. */
 	int     check_host_ip;	/* Also keep track of keys for IP address */
 	int     strict_host_key_checking;	/* Strict host key checking. */
diff --git a/schnorr.c b/schnorr.c
new file mode 100644
index 00000000..e3abe570
--- /dev/null
+++ b/schnorr.c
@@ -0,0 +1,407 @@
+/* $OpenBSD: schnorr.c,v 1.1 2008/11/04 08:22:13 djm Exp $ */
+/*
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Implementation of Schnorr signatures / zero-knowledge proofs, based on
+ * description in:
+ * 	
+ * F. Hao, P. Ryan, "Password Authenticated Key Exchange by Juggling",
+ * 16th Workshop on Security Protocols, Cambridge, April 2008
+ *
+ * http://grouper.ieee.org/groups/1363/Research/contributions/hao-ryan-2008.pdf
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+#include <openssl/evp.h>
+#include <openssl/bn.h>
+
+#include "xmalloc.h"
+#include "buffer.h"
+#include "log.h"
+
+#include "jpake.h"
+
+/* #define SCHNORR_DEBUG */		/* Privacy-violating debugging */
+/* #define SCHNORR_MAIN */		/* Include main() selftest */
+
+/* XXX */
+/* Parametise signature hash? (sha256, sha1, etc.) */
+/* Signature format - include type name, hash type, group params? */
+
+#ifndef SCHNORR_DEBUG
+# define SCHNORR_DEBUG_BN(a)
+# define SCHNORR_DEBUG_BUF(a)
+#else
+# define SCHNORR_DEBUG_BN(a)	jpake_debug3_bn a
+# define SCHNORR_DEBUG_BUF(a)	jpake_debug3_buf a
+#endif /* SCHNORR_DEBUG */
+
+/*
+ * Calculate hash component of Schnorr signature H(g || g^v || g^x || id)
+ * using SHA1. Returns signature as bignum or NULL on error.
+ */
+static BIGNUM *
+schnorr_hash(const BIGNUM *p, const BIGNUM *q, const BIGNUM *g,
+    const BIGNUM *g_v, const BIGNUM *g_x,
+    const u_char *id, u_int idlen)
+{
+	u_char *digest;
+	u_int digest_len;
+	BIGNUM *h;
+	EVP_MD_CTX evp_md_ctx;
+	Buffer b;
+	int success = -1;
+
+	if ((h = BN_new()) == NULL) {
+		error("%s: BN_new", __func__);
+		return NULL;
+	}
+
+	buffer_init(&b);
+	EVP_MD_CTX_init(&evp_md_ctx);
+
+	/* h = H(g || g^v || g^x || id) */
+	buffer_put_bignum2(&b, g);
+	buffer_put_bignum2(&b, g_v);
+	buffer_put_bignum2(&b, g_x);
+	buffer_put_string(&b, id, idlen);
+
+	SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
+	    "%s: hashblob", __func__));
+	if (hash_buffer(buffer_ptr(&b), buffer_len(&b), EVP_sha256(),
+	    &digest, &digest_len) != 0) {
+		error("%s: hash_buffer", __func__);
+		goto out;
+	}
+	if (BN_bin2bn(digest, (int)digest_len, h) == NULL) {
+		error("%s: BN_bin2bn", __func__);
+		goto out;
+	}
+	success = 0;
+	SCHNORR_DEBUG_BN((h, "%s: h = ", __func__));
+ out:
+	buffer_free(&b);
+	EVP_MD_CTX_cleanup(&evp_md_ctx);
+	bzero(digest, digest_len);
+	xfree(digest);
+	digest_len = 0;
+	if (success == 0)
+		return h;
+	BN_clear_free(h);
+	return NULL;
+}
+
+/*
+ * Generate Schnorr signature to prove knowledge of private value 'x' used
+ * in public exponent g^x, under group defined by 'grp_p', 'grp_q' and 'grp_g'
+ * 'idlen' bytes from 'id' will be included in the signature hash as an anti-
+ * replay salt.
+ * On success, 0 is returned and *siglen bytes of signature are returned in
+ * *sig (caller to free). Returns -1 on failure.
+ */
+int
+schnorr_sign(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
+    const BIGNUM *x, const BIGNUM *g_x, const u_char *id, u_int idlen,
+    u_char **sig, u_int *siglen)
+{
+	int success = -1;
+	Buffer b;
+	BIGNUM *h, *tmp, *v, *g_v, *r;
+	BN_CTX *bn_ctx;
+
+	SCHNORR_DEBUG_BN((x, "%s: x = ", __func__));
+	SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
+
+	/* Avoid degenerate cases: g^0 yields a spoofable signature */
+	if (BN_cmp(g_x, BN_value_one()) <= 0) {
+		error("%s: g_x < 1", __func__);
+		return -1;
+	}
+
+	h = g_v = r = tmp = v = NULL;
+	if ((bn_ctx = BN_CTX_new()) == NULL) {
+		error("%s: BN_CTX_new", __func__);
+		goto out;
+	}
+	if ((g_v = BN_new()) == NULL ||
+	    (r = BN_new()) == NULL ||
+	    (tmp = BN_new()) == NULL) {
+		error("%s: BN_new", __func__);
+		goto out;
+	}
+
+	/*
+	 * v must be a random element of Zq, so 1 <= v < q
+	 * we also exclude v = 1, since g^1 looks dangerous
+	 */
+	if ((v = bn_rand_range_gt_one(grp_p)) == NULL) {
+		error("%s: bn_rand_range2", __func__);
+		goto out;
+	}
+	SCHNORR_DEBUG_BN((v, "%s: v = ", __func__));
+
+	/* g_v = g^v mod p */
+	if (BN_mod_exp(g_v, grp_g, v, grp_p, bn_ctx) == -1) {
+		error("%s: BN_mod_exp (g^v mod p)", __func__);
+		goto out;
+	}
+	SCHNORR_DEBUG_BN((g_v, "%s: g_v = ", __func__));
+
+	/* h = H(g || g^v || g^x || id) */
+	if ((h = schnorr_hash(grp_p, grp_q, grp_g, g_v, g_x,
+	    id, idlen)) == NULL) {
+		error("%s: schnorr_hash failed", __func__);
+		goto out;
+	}
+
+	/* r = v - xh mod q */
+	if (BN_mod_mul(tmp, x, h, grp_q, bn_ctx) == -1) {
+		error("%s: BN_mod_mul (tmp = xv mod q)", __func__);
+		goto out;
+	}
+	if (BN_mod_sub(r, v, tmp, grp_q, bn_ctx) == -1) {
+		error("%s: BN_mod_mul (r = v - tmp)", __func__);
+		goto out;
+	}
+	SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
+
+	/* Signature is (g_v, r) */
+	buffer_init(&b);
+	/* XXX sigtype-hash as string? */
+	buffer_put_bignum2(&b, g_v);
+	buffer_put_bignum2(&b, r);
+	*siglen = buffer_len(&b);
+	*sig = xmalloc(*siglen);
+	memcpy(*sig, buffer_ptr(&b), *siglen);
+	SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
+	    "%s: sigblob", __func__));
+	buffer_free(&b);
+	success = 0;
+ out:
+	BN_CTX_free(bn_ctx);
+	if (h != NULL)
+		BN_clear_free(h);
+	if (v != NULL)
+		BN_clear_free(v);
+	BN_clear_free(r);
+	BN_clear_free(g_v);
+	BN_clear_free(tmp);
+
+	return success;
+}
+
+/*
+ * Verify Schnorr signature 'sig' of length 'siglen' against public exponent
+ * g_x (g^x) under group defined by 'grp_p', 'grp_q' and 'grp_g'.
+ * Signature hash will be salted with 'idlen' bytes from 'id'.
+ * Returns -1 on failure, 0 on incorrect signature or 1 on matching signature.
+ */
+int
+schnorr_verify(const BIGNUM *grp_p, const BIGNUM *grp_q, const BIGNUM *grp_g,
+    const BIGNUM *g_x, const u_char *id, u_int idlen,
+    const u_char *sig, u_int siglen)
+{
+	int success = -1;
+	Buffer b;
+	BIGNUM *g_v, *h, *r, *g_xh, *g_r, *expected;
+	BN_CTX *bn_ctx;
+	u_int rlen;
+
+	SCHNORR_DEBUG_BN((g_x, "%s: g_x = ", __func__));
+
+	/* Avoid degenerate cases: g^0 yields a spoofable signature */
+	if (BN_cmp(g_x, BN_value_one()) <= 0) {
+		error("%s: g_x < 1", __func__);
+		return -1;
+	}
+
+	g_v = h = r = g_xh = g_r = expected = NULL;
+	if ((bn_ctx = BN_CTX_new()) == NULL) {
+		error("%s: BN_CTX_new", __func__);
+		goto out;
+	}
+	if ((g_v = BN_new()) == NULL ||
+	    (r = BN_new()) == NULL ||
+	    (g_xh = BN_new()) == NULL ||
+	    (g_r = BN_new()) == NULL ||
+	    (expected = BN_new()) == NULL) {
+		error("%s: BN_new", __func__);
+		goto out;
+	}
+
+	/* Extract g^v and r from signature blob */
+	buffer_init(&b);
+	buffer_append(&b, sig, siglen);
+	SCHNORR_DEBUG_BUF((buffer_ptr(&b), buffer_len(&b),
+	    "%s: sigblob", __func__));
+	buffer_get_bignum2(&b, g_v);
+	buffer_get_bignum2(&b, r);
+	rlen = buffer_len(&b);
+	buffer_free(&b);
+	if (rlen != 0) {
+		error("%s: remaining bytes in signature %d", __func__, rlen);
+		goto out;
+	}
+	buffer_free(&b);
+	SCHNORR_DEBUG_BN((g_v, "%s: g_v = ", __func__));
+	SCHNORR_DEBUG_BN((r, "%s: r = ", __func__));
+
+	/* h = H(g || g^v || g^x || id) */
+	if ((h = schnorr_hash(grp_p, grp_q, grp_g, g_v, g_x,
+	    id, idlen)) == NULL) {
+		error("%s: schnorr_hash failed", __func__);
+		goto out;
+	}
+
+	/* g_xh = (g^x)^h */
+	if (BN_mod_exp(g_xh, g_x, h, grp_p, bn_ctx) == -1) {
+		error("%s: BN_mod_exp (g_x^h mod p)", __func__);
+		goto out;
+	}
+	SCHNORR_DEBUG_BN((g_xh, "%s: g_xh = ", __func__));
+
+	/* g_r = g^r */
+	if (BN_mod_exp(g_r, grp_g, r, grp_p, bn_ctx) == -1) {
+		error("%s: BN_mod_exp (g_x^h mod p)", __func__);
+		goto out;
+	}
+	SCHNORR_DEBUG_BN((g_r, "%s: g_r = ", __func__));
+
+	/* expected = g^r * g_xh */
+	if (BN_mod_mul(expected, g_r, g_xh, grp_p, bn_ctx) == -1) {
+		error("%s: BN_mod_mul (expected = g_r mod p)", __func__);
+		goto out;
+	}
+	SCHNORR_DEBUG_BN((expected, "%s: expected = ", __func__));
+
+	/* Check g_v == expected */
+	success = BN_cmp(expected, g_v) == 0;
+ out:
+	BN_CTX_free(bn_ctx);
+	if (h != NULL)
+		BN_clear_free(h);
+	BN_clear_free(g_v);
+	BN_clear_free(r);
+	BN_clear_free(g_xh);
+	BN_clear_free(g_r);
+	BN_clear_free(expected);
+	return success;
+}
+
+#ifdef SCHNORR_MAIN
+static void
+schnorr_selftest_one(const BIGNUM *grp_p, const BIGNUM *grp_q,
+    const BIGNUM *grp_g, const BIGNUM *x)
+{
+	BIGNUM *g_x;
+	u_char *sig;
+	u_int siglen;
+	BN_CTX *bn_ctx;
+
+	if ((bn_ctx = BN_CTX_new()) == NULL)
+		fatal("%s: BN_CTX_new", __func__);
+	if ((g_x = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	if (BN_mod_exp(g_x, grp_g, x, grp_p, bn_ctx) == -1)
+		fatal("%s: g_x", __func__);
+	if (schnorr_sign(grp_p, grp_q, grp_g, x, g_x, "junk", 4, &sig, &siglen))
+		fatal("%s: schnorr_sign", __func__);
+	if (schnorr_verify(grp_p, grp_q, grp_g, g_x, "junk", 4,
+	    sig, siglen) != 1)
+		fatal("%s: verify fail", __func__);
+	if (schnorr_verify(grp_p, grp_q, grp_g, g_x, "JUNK", 4,
+	    sig, siglen) != 0)
+		fatal("%s: verify should have failed (bad ID)", __func__);
+	sig[4] ^= 1;
+	if (schnorr_verify(grp_p, grp_q, grp_g, g_x, "junk", 4,
+	    sig, siglen) != 0)
+		fatal("%s: verify should have failed (bit error)", __func__);
+	xfree(sig);
+	BN_free(g_x);
+	BN_CTX_free(bn_ctx);
+}
+
+static void
+schnorr_selftest(void)
+{
+	BIGNUM *x;
+	struct jpake_group *grp;
+	u_int i;
+	char *hh;
+
+	grp = jpake_default_group();
+	if ((x = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+	SCHNORR_DEBUG_BN((grp->p, "%s: grp->p = ", __func__));
+	SCHNORR_DEBUG_BN((grp->q, "%s: grp->q = ", __func__));
+	SCHNORR_DEBUG_BN((grp->g, "%s: grp->g = ", __func__));
+
+	/* [1, 20) */
+	for (i = 1; i < 20; i++) {
+		printf("x = %u\n", i);
+		fflush(stdout);
+		if (BN_set_word(x, i) != 1)
+			fatal("%s: set x word", __func__);
+		schnorr_selftest_one(grp->p, grp->q, grp->g, x);
+	}
+
+	/* 100 x random [0, p) */
+	for (i = 0; i < 100; i++) {
+		if (BN_rand_range(x, grp->p) != 1)
+			fatal("%s: BN_rand_range", __func__);
+		hh = BN_bn2hex(x);
+		printf("x = (random) 0x%s\n", hh);
+		free(hh);
+		fflush(stdout);
+		schnorr_selftest_one(grp->p, grp->q, grp->g, x);
+	}
+
+	/* [q-20, q) */
+	if (BN_set_word(x, 20) != 1)
+		fatal("%s: BN_set_word (x = 20)", __func__);
+	if (BN_sub(x, grp->q, x) != 1)
+		fatal("%s: BN_sub (q - x)", __func__);
+	for (i = 0; i < 19; i++) {
+		hh = BN_bn2hex(x);
+		printf("x = (q - %d) 0x%s\n", 20 - i, hh);
+		free(hh);
+		fflush(stdout);
+		schnorr_selftest_one(grp->p, grp->q, grp->g, x);
+		if (BN_add(x, x, BN_value_one()) != 1)
+			fatal("%s: BN_add (x + 1)", __func__);
+	}
+	BN_free(x);
+}
+
+int
+main(int argc, char **argv)
+{
+	log_init(argv[0], SYSLOG_LEVEL_DEBUG3, SYSLOG_FACILITY_USER, 1);
+
+	schnorr_selftest();
+	return 0;
+}
+#endif
+
diff --git a/servconf.c b/servconf.c
index f2d41433..c7d2d0b9 100644
--- a/servconf.c
+++ b/servconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.c,v 1.189 2008/11/03 08:59:41 djm Exp $ */
+/* $OpenBSD: servconf.c,v 1.190 2008/11/04 08:22:13 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -127,6 +127,7 @@ initialize_server_options(ServerOptions *options)
 	options->num_permitted_opens = -1;
 	options->adm_forced_command = NULL;
 	options->chroot_directory = NULL;
+	options->zero_knowledge_password_authentication = -1;
 }
 
 void
@@ -258,6 +259,8 @@ fill_default_server_options(ServerOptions *options)
 		options->authorized_keys_file = _PATH_SSH_USER_PERMITTED_KEYS;
 	if (options->permit_tun == -1)
 		options->permit_tun = SSH_TUNMODE_NO;
+	if (options->zero_knowledge_password_authentication == -1)
+		options->zero_knowledge_password_authentication = 0;
 
 	/* Turn privilege separation on by default */
 	if (use_privsep == -1)
@@ -302,6 +305,7 @@ typedef enum {
 	sGssAuthentication, sGssCleanupCreds, sAcceptEnv, sPermitTunnel,
 	sMatch, sPermitOpen, sForceCommand, sChrootDirectory,
 	sUsePrivilegeSeparation, sAllowAgentForwarding,
+	sZeroKnowledgePasswordAuthentication,
 	sDeprecated, sUnsupported
 } ServerOpCodes;
 
@@ -368,6 +372,11 @@ static struct {
 	{ "kbdinteractiveauthentication", sKbdInteractiveAuthentication, SSHCFG_ALL },
 	{ "challengeresponseauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL },
 	{ "skeyauthentication", sChallengeResponseAuthentication, SSHCFG_GLOBAL }, /* alias */
+#ifdef JPAKE
+	{ "zeroknowledgepasswordauthentication", sZeroKnowledgePasswordAuthentication, SSHCFG_ALL },
+#else
+	{ "zeroknowledgepasswordauthentication", sUnsupported, SSHCFG_ALL },
+#endif
 	{ "checkmail", sDeprecated, SSHCFG_GLOBAL },
 	{ "listenaddress", sListenAddress, SSHCFG_GLOBAL },
 	{ "addressfamily", sAddressFamily, SSHCFG_GLOBAL },
@@ -890,6 +899,10 @@ process_server_config_line(ServerOptions *options, char *line,
 		intptr = &options->password_authentication;
 		goto parse_flag;
 
+	case sZeroKnowledgePasswordAuthentication:
+		intptr = &options->zero_knowledge_password_authentication;
+		goto parse_flag;
+
 	case sKbdInteractiveAuthentication:
 		intptr = &options->kbd_interactive_authentication;
 		goto parse_flag;
@@ -1377,6 +1390,7 @@ copy_set_server_options(ServerOptions *dst, ServerOptions *src, int preauth)
 	M_CP_INTOPT(kerberos_authentication);
 	M_CP_INTOPT(hostbased_authentication);
 	M_CP_INTOPT(kbd_interactive_authentication);
+	M_CP_INTOPT(zero_knowledge_password_authentication);
 	M_CP_INTOPT(permit_root_login);
 	M_CP_INTOPT(permit_empty_passwd);
 
@@ -1579,6 +1593,10 @@ dump_config(ServerOptions *o)
 	dump_cfg_fmtint(sGssAuthentication, o->gss_authentication);
 	dump_cfg_fmtint(sGssCleanupCreds, o->gss_cleanup_creds);
 #endif
+#ifdef JPAKE
+	dump_cfg_fmtint(sZeroKnowledgePasswordAuthentication,
+	    o->zero_knowledge_password_authentication);
+#endif
 	dump_cfg_fmtint(sPasswordAuthentication, o->password_authentication);
 	dump_cfg_fmtint(sKbdInteractiveAuthentication,
 	    o->kbd_interactive_authentication);
diff --git a/servconf.h b/servconf.h
index 40ac64f1..1d4c3a01 100644
--- a/servconf.h
+++ b/servconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.h,v 1.85 2008/06/10 04:50:25 dtucker Exp $ */
+/* $OpenBSD: servconf.h,v 1.86 2008/11/04 08:22:13 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -96,6 +96,8 @@ typedef struct {
 						 * authentication. */
 	int     kbd_interactive_authentication;	/* If true, permit */
 	int     challenge_response_authentication;
+	int     zero_knowledge_password_authentication;
+					/* If true, permit jpake auth */
 	int     permit_empty_passwd;	/* If false, do not permit empty
 					 * passwords. */
 	int     permit_user_env;	/* If true, read ~/.ssh/environment */
diff --git a/ssh2.h b/ssh2.h
index cf56bc4e..1c33dc26 100644
--- a/ssh2.h
+++ b/ssh2.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh2.h,v 1.10 2006/03/25 22:22:43 djm Exp $ */
+/* $OpenBSD: ssh2.h,v 1.11 2008/11/04 08:22:13 djm Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -111,6 +111,12 @@
 #define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ		60
 #define SSH2_MSG_USERAUTH_INFO_REQUEST			60
 #define SSH2_MSG_USERAUTH_INFO_RESPONSE			61
+#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1		60
+#define SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1		61
+#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2		62
+#define SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2		63
+#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM		64
+#define SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM		65
 
 /* connection protocol: generic */
 
@@ -159,3 +165,4 @@
 #define SSH2_OPEN_RESOURCE_SHORTAGE			4
 
 #define SSH2_EXTENDED_DATA_STDERR			1
+
diff --git a/ssh_config.5 b/ssh_config.5
index 254940ef..abc3b0b1 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -34,8 +34,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh_config.5,v 1.114 2008/10/17 18:36:24 stevesk Exp $
-.Dd $Mdocdate: October 17 2008 $
+.\" $OpenBSD: ssh_config.5,v 1.115 2008/11/04 08:22:13 djm Exp $
+.Dd $Mdocdate: November 4 2008 $
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
@@ -1079,6 +1079,17 @@ Specifies the full pathname of the
 program.
 The default is
 .Pa /usr/X11R6/bin/xauth .
+.It Cm ZeroKnowledgePasswordAuthentication
+Specifies whether to use zero knowledge password authentication.
+This authentication method avoids exposure of password to untrusted
+hosts.
+The argument to this keyword must be
+.Dq yes
+or
+.Dq no .
+The default is currently
+.Dq no
+as this method is considered experimental.
 .El
 .Sh PATTERNS
 A
diff --git a/sshconnect2.c b/sshconnect2.c
index 7d0c5e82..a762eec3 100644
--- a/sshconnect2.c
+++ b/sshconnect2.c
@@ -1,6 +1,7 @@
-/* $OpenBSD: sshconnect2.c,v 1.169 2008/11/01 04:50:08 djm Exp $ */
+/* $OpenBSD: sshconnect2.c,v 1.170 2008/11/04 08:22:13 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ * Copyright (c) 2008 Damien Miller.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -67,6 +68,7 @@
 #include "msg.h"
 #include "pathnames.h"
 #include "uidswap.h"
+#include "jpake.h"
 
 #ifdef GSSAPI
 #include "ssh-gss.h"
@@ -201,6 +203,7 @@ struct Authctxt {
 struct Authmethod {
 	char	*name;		/* string to compare against server's list */
 	int	(*userauth)(Authctxt *authctxt);
+	void	(*cleanup)(Authctxt *authctxt);
 	int	*enabled;	/* flag in option struct that enables method */
 	int	*batch_flag;	/* flag in option struct that disables method */
 };
@@ -212,12 +215,18 @@ void	input_userauth_error(int, u_int32_t, void *);
 void	input_userauth_info_req(int, u_int32_t, void *);
 void	input_userauth_pk_ok(int, u_int32_t, void *);
 void	input_userauth_passwd_changereq(int, u_int32_t, void *);
+void	input_userauth_jpake_server_step1(int, u_int32_t, void *);
+void	input_userauth_jpake_server_step2(int, u_int32_t, void *);
+void	input_userauth_jpake_server_confirm(int, u_int32_t, void *);
 
 int	userauth_none(Authctxt *);
 int	userauth_pubkey(Authctxt *);
 int	userauth_passwd(Authctxt *);
 int	userauth_kbdint(Authctxt *);
 int	userauth_hostbased(Authctxt *);
+int	userauth_jpake(Authctxt *);
+
+void	userauth_jpake_cleanup(Authctxt *);
 
 #ifdef GSSAPI
 int	userauth_gssapi(Authctxt *authctxt);
@@ -243,30 +252,43 @@ Authmethod authmethods[] = {
 #ifdef GSSAPI
 	{"gssapi-with-mic",
 		userauth_gssapi,
+		NULL,
 		&options.gss_authentication,
 		NULL},
 #endif
 	{"hostbased",
 		userauth_hostbased,
+		NULL,
 		&options.hostbased_authentication,
 		NULL},
 	{"publickey",
 		userauth_pubkey,
+		NULL,
 		&options.pubkey_authentication,
 		NULL},
+#ifdef JPAKE
+	{"jpake-01@openssh.com",
+		userauth_jpake,
+		userauth_jpake_cleanup,
+		&options.zero_knowledge_password_authentication,
+		&options.batch_mode},
+#endif
 	{"keyboard-interactive",
 		userauth_kbdint,
+		NULL,
 		&options.kbd_interactive_authentication,
 		&options.batch_mode},
 	{"password",
 		userauth_passwd,
+		NULL,
 		&options.password_authentication,
 		&options.batch_mode},
 	{"none",
 		userauth_none,
 		NULL,
+		NULL,
 		NULL},
-	{NULL, NULL, NULL, NULL}
+	{NULL, NULL, NULL, NULL, NULL}
 };
 
 void
@@ -334,6 +356,9 @@ ssh_userauth2(const char *local_user, const char *server_user, char *host,
 void
 userauth(Authctxt *authctxt, char *authlist)
 {
+	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
+		authctxt->method->cleanup(authctxt);
+
 	if (authctxt->methoddata) {
 		xfree(authctxt->methoddata);
 		authctxt->methoddata = NULL;
@@ -851,6 +876,209 @@ input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
 	    &input_userauth_passwd_changereq);
 }
 
+#ifdef JPAKE
+static char *
+pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
+{
+	/* OpenBSD crypt(3) handles all of these */
+	if (strcmp(crypt_scheme, "crypt") == 0 ||
+	    strcmp(crypt_scheme, "bcrypt") == 0 ||
+	    strcmp(crypt_scheme, "md5crypt") == 0 ||
+	    strcmp(crypt_scheme, "crypt-extended") == 0)
+		return xstrdup(crypt(password, salt));
+	error("%s: unsupported password encryption scheme \"%.100s\"",
+	    __func__, crypt_scheme);
+	return NULL;
+}
+
+static BIGNUM *
+jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
+    const char *salt)
+{
+	char prompt[256], *password, *crypted;
+	u_char *secret;
+	u_int secret_len;
+	BIGNUM *ret;
+
+	snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
+	    authctxt->server_user, authctxt->host);
+	password = read_passphrase(prompt, 0);
+
+	if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
+		logit("Disabling %s authentication", authctxt->method->name);
+		authctxt->method->enabled = NULL;
+		/* Continue with an empty password to fail gracefully */
+		crypted = xstrdup("");
+	}
+
+#ifdef JPAKE_DEBUG
+	debug3("%s: salt = %s", __func__, salt);
+	debug3("%s: scheme = %s", __func__, crypt_scheme);
+	debug3("%s: crypted = %s", __func__, crypted);
+#endif
+
+	if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
+	    &secret, &secret_len) != 0)
+		fatal("%s: hash_buffer", __func__);
+
+	bzero(password, strlen(password));
+	bzero(crypted, strlen(crypted));
+	xfree(password);
+	xfree(crypted);
+
+	if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
+		fatal("%s: BN_bin2bn (secret)", __func__);
+	bzero(secret, secret_len);
+	xfree(secret);
+
+	return ret;
+}
+
+/* ARGSUSED */
+void
+input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	struct jpake_ctx *pctx = authctxt->methoddata;
+	u_char *x3_proof, *x4_proof, *x2_s_proof;
+	u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
+	char *crypt_scheme, *salt;
+
+	/* Disable this message */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
+
+	if ((pctx->g_x3 = BN_new()) == NULL ||
+	    (pctx->g_x4 = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	/* Fetch step 1 values */
+	crypt_scheme = packet_get_string(NULL);
+	salt = packet_get_string(NULL);
+	pctx->server_id = packet_get_string(&pctx->server_id_len);
+	packet_get_bignum2(pctx->g_x3);
+	packet_get_bignum2(pctx->g_x4);
+	x3_proof = packet_get_string(&x3_proof_len);
+	x4_proof = packet_get_string(&x4_proof_len);
+	packet_check_eom();
+
+	JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
+
+	/* Obtain password and derive secret */
+	pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
+	bzero(crypt_scheme, strlen(crypt_scheme));
+	bzero(salt, strlen(salt));
+	xfree(crypt_scheme);
+	xfree(salt);
+	JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
+
+	/* Calculate step 2 values */
+	jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
+	    pctx->g_x3, pctx->g_x4, pctx->x2,
+	    pctx->server_id, pctx->server_id_len,
+	    pctx->client_id, pctx->client_id_len,
+	    x3_proof, x3_proof_len,
+	    x4_proof, x4_proof_len,
+	    &pctx->a,
+	    &x2_s_proof, &x2_s_proof_len);
+
+	bzero(x3_proof, x3_proof_len);
+	bzero(x4_proof, x4_proof_len);
+	xfree(x3_proof);
+	xfree(x4_proof);
+
+	JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
+
+	/* Send values for step 2 */
+	packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
+	packet_put_bignum2(pctx->a);
+	packet_put_string(x2_s_proof, x2_s_proof_len);
+	packet_send();
+
+	bzero(x2_s_proof, x2_s_proof_len);
+	xfree(x2_s_proof);
+
+	/* Expect step 2 packet from peer */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
+	    input_userauth_jpake_server_step2);
+}
+
+/* ARGSUSED */
+void
+input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	struct jpake_ctx *pctx = authctxt->methoddata;
+	u_char *x4_s_proof;
+	u_int x4_s_proof_len;
+
+	/* Disable this message */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
+
+	if ((pctx->b = BN_new()) == NULL)
+		fatal("%s: BN_new", __func__);
+
+	/* Fetch step 2 values */
+	packet_get_bignum2(pctx->b);
+	x4_s_proof = packet_get_string(&x4_s_proof_len);
+	packet_check_eom();
+
+	JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
+
+	/* Derive shared key and calculate confirmation hash */
+	jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
+	    pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
+	    pctx->client_id, pctx->client_id_len,
+	    pctx->server_id, pctx->server_id_len,
+	    session_id2, session_id2_len,
+	    x4_s_proof, x4_s_proof_len,
+	    &pctx->k,
+	    &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
+
+	bzero(x4_s_proof, x4_s_proof_len);
+	xfree(x4_s_proof);
+
+	JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
+
+	/* Send key confirmation proof */
+	packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
+	packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
+	packet_send();
+
+	/* Expect confirmation from peer */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
+	    input_userauth_jpake_server_confirm);
+}
+
+/* ARGSUSED */
+void
+input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
+{
+	Authctxt *authctxt = ctxt;
+	struct jpake_ctx *pctx = authctxt->methoddata;
+
+	/* Disable this message */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
+
+	pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
+	packet_check_eom();
+
+	JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
+
+	/* Verify expected confirmation hash */
+	if (jpake_check_confirm(pctx->k,
+	    pctx->server_id, pctx->server_id_len,
+	    session_id2, session_id2_len,
+	    pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
+		debug("%s: %s success", __func__, authctxt->method->name);
+	else {
+		debug("%s: confirmation mismatch", __func__);
+		/* XXX stash this so if auth succeeds then we can warn/kill */
+	}
+
+	userauth_jpake_cleanup(authctxt);
+}
+#endif /* JPAKE */
+
 static int
 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
     u_char *data, u_int datalen)
@@ -1425,6 +1653,76 @@ userauth_hostbased(Authctxt *authctxt)
 	return 1;
 }
 
+#ifdef JPAKE
+int
+userauth_jpake(Authctxt *authctxt)
+{
+	struct jpake_ctx *pctx;
+	u_char *x1_proof, *x2_proof;
+	u_int x1_proof_len, x2_proof_len;
+	static int attempt = 0; /* XXX share with userauth_password's? */
+
+	if (attempt++ >= options.number_of_password_prompts)
+		return 0;
+	if (attempt != 1)
+		error("Permission denied, please try again.");
+
+	if (authctxt->methoddata != NULL)
+		fatal("%s: authctxt->methoddata already set (%p)",
+		    __func__, authctxt->methoddata);
+
+	authctxt->methoddata = pctx = jpake_new();
+
+	/*
+	 * Send request immediately, to get the protocol going while
+	 * we do the initial computations.
+	 */
+	packet_start(SSH2_MSG_USERAUTH_REQUEST);
+	packet_put_cstring(authctxt->server_user);
+	packet_put_cstring(authctxt->service);
+	packet_put_cstring(authctxt->method->name);
+	packet_send();
+	packet_write_wait();
+
+	jpake_step1(pctx->grp,
+	    &pctx->client_id, &pctx->client_id_len,
+	    &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
+	    &x1_proof, &x1_proof_len,
+	    &x2_proof, &x2_proof_len);
+
+	JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
+
+	packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
+	packet_put_string(pctx->client_id, pctx->client_id_len);
+	packet_put_bignum2(pctx->g_x1);
+	packet_put_bignum2(pctx->g_x2);
+	packet_put_string(x1_proof, x1_proof_len);
+	packet_put_string(x2_proof, x2_proof_len);
+	packet_send();
+
+	bzero(x1_proof, x1_proof_len);
+	bzero(x2_proof, x2_proof_len);
+	xfree(x1_proof);
+	xfree(x2_proof);
+
+	/* Expect step 1 packet from peer */
+	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
+	    input_userauth_jpake_server_step1);
+
+	return 1;
+}
+
+void
+userauth_jpake_cleanup(Authctxt *authctxt)
+{
+	debug3("%s: clean up", __func__);
+	if (authctxt->methoddata != NULL) {
+		jpake_free(authctxt->methoddata);
+		authctxt->methoddata = NULL;
+	}
+}
+#endif /* JPAKE */
+
 /* find auth method */
 
 /*
@@ -1526,3 +1824,4 @@ authmethods_get(void)
 	buffer_free(&b);
 	return list;
 }
+
diff --git a/sshd_config.5 b/sshd_config.5
index 06fe5fd3..a4a4be6e 100644
--- a/sshd_config.5
+++ b/sshd_config.5
@@ -34,8 +34,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd_config.5,v 1.97 2008/10/09 03:50:54 djm Exp $
-.Dd $Mdocdate: October 9 2008 $
+.\" $OpenBSD: sshd_config.5,v 1.98 2008/11/04 08:22:13 djm Exp $
+.Dd $Mdocdate: November 4 2008 $
 .Dt SSHD_CONFIG 5
 .Os
 .Sh NAME
@@ -612,8 +612,9 @@ Available keywords are
 .Cm RSAAuthentication ,
 .Cm X11DisplayOffset ,
 .Cm X11Forwarding ,
+.Cm X11UseLocalHost ,
 and
-.Cm X11UseLocalHost .
+.Cm ZeroKnowledgePasswordAuthentication .
 .It Cm MaxAuthTries
 Specifies the maximum number of authentication attempts permitted per
 connection.
@@ -1004,6 +1005,17 @@ Specifies the full pathname of the
 program.
 The default is
 .Pa /usr/X11R6/bin/xauth .
+.It Cm ZeroKnowledgePasswordAuthentication
+Specifies whether to use zero knowledge password authentication.
+This authentication method avoids exposure of password to untrusted
+hosts.
+The argument to this keyword must be
+.Dq yes
+or
+.Dq no .
+The default is currently
+.Dq no
+as this method is considered experimental.
 .El
 .Sh TIME FORMATS
 .Xr sshd 8