2005-02-16 Mark Wielaard <mark@klomp.org>

       * Makefile.am (ordinary_java_source_files): Add new files
       gnu/java/security/ber/BER.java,
       gnu/java/security/ber/BEREncodingException.java,
       gnu/java/security/ber/BERReader.java,
       gnu/java/security/ber/BERValue.java,
       gnu/java/security/pkcs/PKCS7SignedData.java and
       gnu/java/security/pkcs/SignerInfo.java.
       * Makefile.in: Regenerated.

2005-02-16  Casey Marshall  <csm@gnu.org>

       * gnu/java/security/provider/GnuDSAPrivateKey.java
       (encodedKey): new field.
       (getFormat): return "PKCS#8".
       (getEncoded): implemented.
       (toString): check for 'null' values.
       * gnu/java/security/provider/GnuDSAPublicKey.java
       (encodedKey): new field.
       (getFormat): return "X.509".
       (getEncoded): implemented.
       (toString): check for 'null' values.

2005-02-16  Michael Koch  <konqueror@gmx.de>

       * java/util/jar/JarFile.java: Imports reworked.

2005-02-16  Mark Wielaard  <mark@klomp.org>

       * java/util/jar/JarFile.java (verify): Make package private.
       (signaturesRead): Likewise.
       (verified): Likewise.
       (entryCerts): Likewise.
       (DEBUG): Likewise.
       (debug): Likewise.
       (entries): Construct new JarEnumeration with reference to this.
       (JarEnumeration): Make static.
       (JarEnumeration.jarfile): New field.
       (JarEnumeration.nextElement): Use and synchronize on jarfile.
       Compare verified value to Boolean.TRUE or Boolean.False only
       when verify is true.
       (getEntry): Make synchronized. Compare value of verified to
       Boolean.TRUE.
       (getInputStream): Construct EntryInputStream with reference to this.
       (getManifest): Make synchronized.
       (EntryInputStream): Make static.
       (EntryInputStream.jarfile): New field.
       (EntryInputStream.EntryInputStream): Check if manifest exists,
       before getting attributes.
       (eof): Synchronize on jarfile.

2005-02-16  Casey Marshall  <csm@gnu.org>

       * java/util/jar/JarFile.java (verify): return if the jar is signed
       with an unsupported algorithm.

2005-02-16  Mark Wielaard  <mark@klomp.org>

       * java/util/jar/JarFile.java (EntryInputStream): Add actual
       InputStream as argument.
       (getInputStream): Construct a new EntryInputStream with the result of
       super.getInputStream(entry).

2005-02-16  Casey Marshall  <csm@gnu.org>

       Signed JAR file support.
       * java/net/URLClassLoader.java
       (JarURLResource.getCertificates): re-read jar entry to ensure
       certificates are picked up.
       (findClass): fill in class `signers' field, too.
       * java/util/jar/JarFile.java (META_INF): new constant.
       (PKCS7_DSA_SUFFIX): new constant.
       (PKCS7_RSA_SUFFIX): new constant.
       (DIGEST_KEY_SUFFIX): new constant.
       (SF_SUFFIX): new constant.
       (MD2_OID): new constant.
       (MD4_OID): new constant.
       (MD5_OID): new constant.
       (SHA1_OID): new constant.
       (DSA_ENCRYPTION_OID): new constant.
       (RSA_ENCRYPTION_OID): new constant.
       (signaturesRead): new field.
       (verified): new field.
       (entryCerts): new field.
       (DEBUG): new constant.
       (debug): new method.
       (JarEnumeration.nextElement): fill in entry certificates, read
       signatures if they haven't been read.
       (getEntry): likewise.
       (getInputStream): verify stream if it hasn't been verified yet.
       (readSignatures): new method.
       (verify): new method.
       (verifyHashes): new method.
       (readManifestEntry): new method.
       (EntryInputStream): new class.
       * gnu/java/io/Base64InputStream.java (decode): new class
       method.
       * gnu/java/security/der/DERReader.java don't make class
       final.
       (in): made protected.
       (encBuf): likewise.
       (readLength): likewise.
       * gnu/java/security/ber/BER.java,
       * gnu/java/security/ber/BEREncodingException.java,
       * gnu/java/security/ber/BERReader.java,
       * gnu/java/security/ber/BERValue.java,
       * gnu/java/security/pkcs/PKCS7SignedData.java,
       * gnu/java/security/pkcs/SignerInfo.java:
       new files.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@95124 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 714 insertions, 15 deletions

diff --git a/libjava/java/util/jar/JarFile.java b/libjava/java/util/jar/JarFile.java
index 070b3375d19..c66881f1900 100644
--- a/libjava/java/util/jar/JarFile.java
+++ b/libjava/java/util/jar/JarFile.java
@@ -35,13 +35,38 @@ this exception to your version of the library, but you are not
 obligated to do so.  If you do not wish to do so, delete this
 exception statement from your version. */
 
+
 package java.util.jar;
 
+import gnu.java.io.Base64InputStream;
+import gnu.java.security.OID;
+import gnu.java.security.pkcs.PKCS7SignedData;
+import gnu.java.security.pkcs.SignerInfo;
+
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.security.InvalidKeyException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.Signature;
+import java.security.SignatureException;
+import java.security.cert.CRLException;
+import java.security.cert.Certificate;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+import java.util.Arrays;
 import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipException;
 import java.util.zip.ZipFile;
@@ -52,11 +77,11 @@ import java.util.zip.ZipFile;
  * Note that this class is not a subclass of java.io.File but a subclass of
  * java.util.zip.ZipFile and you can only read JarFiles with it (although
  * there are constructors that take a File object).
- * <p>
- * XXX - verification of Manifest signatures is not yet implemented.
  *
  * @since 1.2
  * @author Mark Wielaard (mark@klomp.org)
+ * @author Casey Marshall (csm@gnu.org) wrote the certificate and entry
+ *  verification code.
  */
 public class JarFile extends ZipFile
 {
@@ -65,6 +90,29 @@ public class JarFile extends ZipFile
   /** The name of the manifest entry: META-INF/MANIFEST.MF */
   public static final String MANIFEST_NAME = "META-INF/MANIFEST.MF";
 
+  /** The META-INF directory entry. */
+  private static final String META_INF = "META-INF/";
+
+  /** The suffix for PKCS7 DSA signature entries. */
+  private static final String PKCS7_DSA_SUFFIX = ".DSA";
+
+  /** The suffix for PKCS7 RSA signature entries. */
+  private static final String PKCS7_RSA_SUFFIX = ".RSA";
+
+  /** The suffix for digest attributes. */
+  private static final String DIGEST_KEY_SUFFIX = "-Digest";
+
+  /** The suffix for signature files. */
+  private static final String SF_SUFFIX = ".SF";
+
+  // Signature OIDs.
+  private static final OID MD2_OID = new OID("1.2.840.113549.2.2");
+  private static final OID MD4_OID = new OID("1.2.840.113549.2.4");
+  private static final OID MD5_OID = new OID("1.2.840.113549.2.5");
+  private static final OID SHA1_OID = new OID("1.3.14.3.2.26");
+  private static final OID DSA_ENCRYPTION_OID = new OID("1.2.840.10040.4.1");
+  private static final OID RSA_ENCRYPTION_OID = new OID("1.2.840.113549.1.1.1");
+
   /**
    * The manifest of this file, if any, otherwise null.
    * Read when first needed.
@@ -72,11 +120,34 @@ public class JarFile extends ZipFile
   private Manifest manifest;
 
   /** Whether to verify the manifest and all entries. */
-  private boolean verify;
+  boolean verify;
 
   /** Whether the has already been loaded. */
   private boolean manifestRead = false;
 
+  /** Whether the signature files have been loaded. */
+  boolean signaturesRead = false;
+
+  /**
+   * A map between entry names and booleans, signaling whether or
+   * not that entry has been verified.
+   * Only be accessed with lock on this JarFile*/
+  HashMap verified = new HashMap();
+
+  /**
+   * A mapping from entry name to certificates, if any.
+   * Only accessed with lock on this JarFile.
+   */
+  HashMap entryCerts;
+
+  static boolean DEBUG = false;
+  static void debug(Object msg)
+  {
+    System.err.print(JarFile.class.getName());
+    System.err.print(" >>> ");
+    System.err.println(msg);
+  }
+
   // Constructors
 
   /**
@@ -235,22 +306,23 @@ public class JarFile extends ZipFile
    */
   public Enumeration entries() throws IllegalStateException
   {
-    return new JarEnumeration(super.entries());
+    return new JarEnumeration(super.entries(), this);
   }
 
   /**
    * Wraps a given Zip Entries Enumeration. For every zip entry a
    * JarEntry is created and the corresponding Attributes are looked up.
-   * XXX - Should also look up the certificates.
    */
-  private class JarEnumeration implements Enumeration
+  private static class JarEnumeration implements Enumeration
   {
 
     private final Enumeration entries;
+    private final JarFile jarfile;
 
-    JarEnumeration(Enumeration e)
+    JarEnumeration(Enumeration e, JarFile f)
     {
       entries = e;
+      jarfile = f;
     }
 
     public boolean hasMoreElements()
@@ -265,7 +337,7 @@ public class JarFile extends ZipFile
       Manifest manifest;
       try
 	{
-	  manifest = getManifest();
+	  manifest = jarfile.getManifest();
 	}
       catch (IOException ioe)
 	{
@@ -276,7 +348,36 @@ public class JarFile extends ZipFile
 	{
 	  jar.attr = manifest.getAttributes(jar.getName());
 	}
-      // XXX jar.certs
+
+      synchronized(jarfile)
+	{
+	  if (!jarfile.signaturesRead)
+	    try
+	      {
+		jarfile.readSignatures();
+	      }
+	    catch (IOException ioe)
+	      {
+		if (JarFile.DEBUG)
+		  {
+		    JarFile.debug(ioe);
+		    ioe.printStackTrace();
+		  }
+		jarfile.signaturesRead = true; // fudge it.
+	      }
+
+	  // Include the certificates only if we have asserted that the
+	  // signatures are valid. This means the certificates will not be
+	  // available if the entry hasn't been read yet.
+	  if (jarfile.entryCerts != null
+	      && jarfile.verified.get(zip.getName()) == Boolean.TRUE)
+	    {
+	      Set certs = (Set) jarfile.entryCerts.get(jar.getName());
+	      if (certs != null)
+		jar.certs = (Certificate[])
+		  certs.toArray(new Certificate[certs.size()]);
+	    }
+	}
       return jar;
     }
   }
@@ -286,7 +387,7 @@ public class JarFile extends ZipFile
    * It actually returns a JarEntry not a zipEntry
    * @param name XXX
    */
-  public ZipEntry getEntry(String name)
+  public synchronized ZipEntry getEntry(String name)
   {
     ZipEntry entry = super.getEntry(name);
     if (entry != null)
@@ -305,7 +406,33 @@ public class JarFile extends ZipFile
 	if (manifest != null)
 	  {
 	    jarEntry.attr = manifest.getAttributes(name);
-	    // XXX jarEntry.certs
+          }
+
+	if (!signaturesRead)
+	  try
+	    {
+	      readSignatures();
+	    }
+	  catch (IOException ioe)
+	    {
+	      if (DEBUG)
+		{
+		  debug(ioe);
+		  ioe.printStackTrace();
+		}
+	      signaturesRead = true;
+	    }
+	// See the comments in the JarEnumeration for why we do this
+	// check.
+	if (DEBUG)
+	  debug("entryCerts=" + entryCerts + " verified " + name
+		+ " ? " + verified.get(name));
+	if (entryCerts != null && verified.get(name) == Boolean.TRUE)
+	  {
+	    Set certs = (Set) entryCerts.get(name);
+	    if (certs != null)
+	      jarEntry.certs = (Certificate[])
+		certs.toArray(new Certificate[certs.size()]);
 	  }
 	return jarEntry;
       }
@@ -313,15 +440,32 @@ public class JarFile extends ZipFile
   }
 
   /**
-   * XXX should verify the inputstream
-   * @param entry XXX
+   * Returns an input stream for the given entry. If configured to
+   * verify entries, the input stream returned will verify them while
+   * the stream is read, but only on the first time.
+   *
+   * @param entry The entry to get the input stream for.
    * @exception ZipException XXX
    * @exception IOException XXX
    */
   public synchronized InputStream getInputStream(ZipEntry entry) throws
     ZipException, IOException
   {
-    return super.getInputStream(entry);	// XXX verify
+    // If we haven't verified the hash, do it now.
+    if (!verified.containsKey(entry.getName()) && verify)
+      {
+        if (DEBUG)
+          debug("reading and verifying " + entry);
+        return new EntryInputStream(entry, super.getInputStream(entry), this);
+      }
+    else
+      {
+        if (DEBUG)
+          debug("reading already verified entry " + entry);
+        if (verify && verified.get(entry.getName()) == Boolean.FALSE)
+          throw new ZipException("digest for " + entry + " is invalid");
+        return super.getInputStream(entry);
+      }
   }
 
   /**
@@ -342,11 +486,566 @@ public class JarFile extends ZipFile
    * Returns the manifest for this JarFile or null when the JarFile does not
    * contain a manifest file.
    */
-  public Manifest getManifest() throws IOException
+  public synchronized Manifest getManifest() throws IOException
   {
     if (!manifestRead)
       manifest = readManifest();
 
     return manifest;
   }
+
+  // Only called with lock on this JarFile.
+  private void readSignatures() throws IOException
+  {
+    Map pkcs7Dsa = new HashMap();
+    Map pkcs7Rsa = new HashMap();
+    Map sigFiles = new HashMap();
+
+    // Phase 1: Read all signature files. These contain the user
+    // certificates as well as the signatures themselves.
+    for (Enumeration e = super.entries(); e.hasMoreElements(); )
+      {
+        ZipEntry ze = (ZipEntry) e.nextElement();
+        String name = ze.getName();
+        if (name.startsWith(META_INF))
+          {
+            String alias = name.substring(META_INF.length());
+            if (alias.lastIndexOf('.') >= 0)
+              alias = alias.substring(0, alias.lastIndexOf('.'));
+
+            if (name.endsWith(PKCS7_DSA_SUFFIX) || name.endsWith(PKCS7_RSA_SUFFIX))
+              {
+                if (DEBUG)
+                  debug("reading PKCS7 info from " + name + ", alias=" + alias);
+                PKCS7SignedData sig = null;
+                try
+                  {
+                    sig = new PKCS7SignedData(super.getInputStream(ze));
+                  }
+                catch (CertificateException ce)
+                  {
+                    IOException ioe = new IOException("certificate parsing error");
+                    ioe.initCause(ce);
+                    throw ioe;
+                  }
+                catch (CRLException crle)
+                  {
+                    IOException ioe = new IOException("CRL parsing error");
+                    ioe.initCause(crle);
+                    throw ioe;
+                  }
+                if (name.endsWith(PKCS7_DSA_SUFFIX))
+                  pkcs7Dsa.put(alias, sig);
+                else if (name.endsWith(PKCS7_RSA_SUFFIX))
+                  pkcs7Rsa.put(alias, sig);
+              }
+            else if (name.endsWith(SF_SUFFIX))
+              {
+                if (DEBUG)
+                  debug("reading signature file for " + alias + ": " + name);
+                Manifest sf = new Manifest(super.getInputStream(ze));
+                sigFiles.put(alias, sf);
+                if (DEBUG)
+                  debug("result: " + sf);
+              }
+          }
+      }
+
+    // Phase 2: verify the signatures on any signature files.
+    Set validCerts = new HashSet();
+    Map entryCerts = new HashMap();
+    for (Iterator it = sigFiles.entrySet().iterator(); it.hasNext(); )
+      {
+        int valid = 0;
+        Map.Entry e = (Map.Entry) it.next();
+        String alias = (String) e.getKey();
+
+        PKCS7SignedData sig = (PKCS7SignedData) pkcs7Dsa.get(alias);
+        if (sig != null)
+          {
+            Certificate[] certs = sig.getCertificates();
+            Set signerInfos = sig.getSignerInfos();
+            for (Iterator it2 = signerInfos.iterator(); it2.hasNext(); )
+              verify(certs, (SignerInfo) it2.next(), alias, validCerts);
+          }
+
+        sig = (PKCS7SignedData) pkcs7Rsa.get(alias);
+        if (sig != null)
+          {
+            Certificate[] certs = sig.getCertificates();
+            Set signerInfos = sig.getSignerInfos();
+            for (Iterator it2 = signerInfos.iterator(); it2.hasNext(); )
+              verify(certs, (SignerInfo) it2.next(), alias, validCerts);
+          }
+
+        // It isn't a signature for anything. Punt it.
+        if (validCerts.isEmpty())
+          {
+            it.remove();
+            continue;
+          }
+
+        entryCerts.put(e.getValue(), new HashSet(validCerts));
+        validCerts.clear();
+      }
+
+    // Phase 3: verify the signature file signatures against the manifest,
+    // mapping the entry name to the target certificates.
+    this.entryCerts = new HashMap();
+    for (Iterator it = entryCerts.entrySet().iterator(); it.hasNext(); )
+      {
+        Map.Entry e = (Map.Entry) it.next();
+        Manifest sigfile = (Manifest) e.getKey();
+        Map entries = sigfile.getEntries();
+        Set certificates = (Set) e.getValue();
+
+        for (Iterator it2 = entries.entrySet().iterator(); it2.hasNext(); )
+          {
+            Map.Entry e2 = (Map.Entry) it2.next();
+            String entryname = String.valueOf(e2.getKey());
+            Attributes attr = (Attributes) e2.getValue();
+            if (verifyHashes(entryname, attr))
+              {
+                if (DEBUG)
+                  debug("entry " + entryname + " has certificates " + certificates);
+                Set s = (Set) this.entryCerts.get(entryname);
+                if (s != null)
+                  s.addAll(certificates);
+                else
+                  this.entryCerts.put(entryname, new HashSet(certificates));
+              }
+          }
+      }
+
+    signaturesRead = true;
+  }
+
+  /**
+   * Tell if the given signer info is over the given alias's signature file,
+   * given one of the certificates specified.
+   */
+  private void verify(Certificate[] certs, SignerInfo signerInfo,
+                      String alias, Set validCerts)
+  {
+    Signature sig = null;
+    try
+      {
+        OID alg = signerInfo.getDigestEncryptionAlgorithmId();
+        if (alg.equals(DSA_ENCRYPTION_OID))
+          {
+            if (!signerInfo.getDigestAlgorithmId().equals(SHA1_OID))
+              return;
+            sig = Signature.getInstance("SHA1withDSA");
+          }
+        else if (alg.equals(RSA_ENCRYPTION_OID))
+          {
+            OID hash = signerInfo.getDigestAlgorithmId();
+            if (hash.equals(MD2_OID))
+              sig = Signature.getInstance("md2WithRsaEncryption");
+            else if (hash.equals(MD4_OID))
+              sig = Signature.getInstance("md4WithRsaEncryption");
+            else if (hash.equals(MD5_OID))
+              sig = Signature.getInstance("md5WithRsaEncryption");
+            else if (hash.equals(SHA1_OID))
+              sig = Signature.getInstance("sha1WithRsaEncryption");
+            else
+              return;
+          }
+        else
+          {
+            if (DEBUG)
+              debug("unsupported signature algorithm: " + alg);
+            return;
+          }
+      }
+    catch (NoSuchAlgorithmException nsae)
+      {
+        if (DEBUG)
+          {
+            debug(nsae);
+            nsae.printStackTrace();
+          }
+        return;
+      }
+    ZipEntry sigFileEntry = super.getEntry(META_INF + alias + SF_SUFFIX);
+    if (sigFileEntry == null)
+      return;
+    for (int i = 0; i < certs.length; i++)
+      {
+        if (!(certs[i] instanceof X509Certificate))
+          continue;
+        X509Certificate cert = (X509Certificate) certs[i];
+        if (!cert.getIssuerX500Principal().equals(signerInfo.getIssuer()) ||
+            !cert.getSerialNumber().equals(signerInfo.getSerialNumber()))
+          continue;
+        try
+          {
+            sig.initVerify(cert.getPublicKey());
+            InputStream in = super.getInputStream(sigFileEntry);
+            if (in == null)
+              continue;
+            byte[] buf = new byte[1024];
+            int len = 0;
+            while ((len = in.read(buf)) != -1)
+              sig.update(buf, 0, len);
+            if (sig.verify(signerInfo.getEncryptedDigest()))
+              {
+                if (DEBUG)
+                  debug("signature for " + cert.getSubjectDN() + " is good");
+                validCerts.add(cert);
+              }
+          }
+        catch (IOException ioe)
+          {
+            continue;
+          }
+        catch (InvalidKeyException ike)
+          {
+            continue;
+          }
+        catch (SignatureException se)
+          {
+            continue;
+          }
+      }
+  }
+
+  /**
+   * Verifies that the digest(s) in a signature file were, in fact, made
+   * over the manifest entry for ENTRY.
+   *
+   * @param entry The entry name.
+   * @param attr The attributes from the signature file to verify.
+   */
+  private boolean verifyHashes(String entry, Attributes attr)
+  {
+    int verified = 0;
+
+    // The bytes for ENTRY's manifest entry, which are signed in the
+    // signature file.
+    byte[] entryBytes = null;
+    try
+      {
+        entryBytes = readManifestEntry(super.getEntry(entry));
+      }
+    catch (IOException ioe)
+      {
+        if (DEBUG)
+          {
+            debug(ioe);
+            ioe.printStackTrace();
+          }
+        return false;
+      }
+
+    for (Iterator it = attr.entrySet().iterator(); it.hasNext(); )
+      {
+        Map.Entry e = (Map.Entry) it.next();
+        String key = String.valueOf(e.getKey());
+        if (!key.endsWith(DIGEST_KEY_SUFFIX))
+          continue;
+        String alg = key.substring(0, key.length() - DIGEST_KEY_SUFFIX.length());
+        try
+          {
+            byte[] hash = Base64InputStream.decode((String) e.getValue());
+            MessageDigest md = MessageDigest.getInstance(alg);
+            md.update(entryBytes);
+            byte[] hash2 = md.digest();
+            if (DEBUG)
+              debug("verifying SF entry " + entry + " alg: " + md.getAlgorithm()
+                    + " expect=" + new java.math.BigInteger(hash).toString(16)
+                    + " comp=" + new java.math.BigInteger(hash2).toString(16));
+            if (!Arrays.equals(hash, hash2))
+              return false;
+            verified++;
+          }
+        catch (IOException ioe)
+          {
+            if (DEBUG)
+              {
+                debug(ioe);
+                ioe.printStackTrace();
+              }
+            return false;
+          }
+        catch (NoSuchAlgorithmException nsae)
+          {
+            if (DEBUG)
+              {
+                debug(nsae);
+                nsae.printStackTrace();
+              }
+            return false;
+          }
+      }
+
+    // We have to find at least one valid digest.
+    return verified > 0;
+  }
+
+  /**
+   * Read the raw bytes that comprise a manifest entry. We can't use the
+   * Manifest object itself, because that loses information (such as line
+   * endings, and order of entries).
+   */
+  private byte[] readManifestEntry(ZipEntry entry) throws IOException
+  {
+    InputStream in = super.getInputStream(super.getEntry(MANIFEST_NAME));
+    ByteArrayOutputStream out = new ByteArrayOutputStream();
+    byte[] target = ("Name: " + entry.getName()).getBytes();
+    int t = 0, c, prev = -1, state = 0, l = -1;
+
+    while ((c = in.read()) != -1)
+      {
+//         if (DEBUG)
+//           debug("read "
+//                 + (c == '\n' ? "\\n" : (c == '\r' ? "\\r" : String.valueOf((char) c)))
+//                 + " state=" + state + " prev="
+//                 + (prev == '\n' ? "\\n" : (prev == '\r' ? "\\r" : String.valueOf((char) prev)))
+//                 + " t=" + t + (t < target.length ? (" target[t]=" + (char) target[t]) : "")
+//                 + " l=" + l);
+        switch (state)
+          {
+
+          // Step 1: read until we find the "target" bytes: the start
+          // of the entry we need to read.
+          case 0:
+            if (((byte) c) != target[t])
+              t = 0;
+            else
+              {
+                t++;
+                if (t == target.length)
+                  {
+                    out.write(target);
+                    state = 1;
+                  }
+              }
+            break;
+
+          // Step 2: assert that there is a newline character after
+          // the "target" bytes.
+          case 1:
+            if (c != '\n' && c != '\r')
+              {
+                out.reset();
+                t = 0;
+                state = 0;
+              }
+            else
+              {
+                out.write(c);
+                state = 2;
+              }
+            break;
+
+          // Step 3: read this whole entry, until we reach an empty
+          // line.
+          case 2:
+            if (c == '\n')
+              {
+                out.write(c);
+                // NL always terminates a line.
+                if (l == 0 || (l == 1 && prev == '\r'))
+                  return out.toByteArray();
+                l = 0;
+              }
+            else
+              {
+                // Here we see a blank line terminated by a CR,
+                // followed by the next entry. Technically, `c' should
+                // always be 'N' at this point.
+                if (l == 1 && prev == '\r')
+                  return out.toByteArray();
+                out.write(c);
+                l++;
+              }
+            prev = c;
+            break;
+
+          default:
+            throw new RuntimeException("this statement should be unreachable");
+          }
+      }
+
+    // The last entry, with a single CR terminating the line.
+    if (state == 2 && prev == '\r' && l == 0)
+      return out.toByteArray();
+
+    // We should not reach this point, we didn't find the entry (or, possibly,
+    // it is the last entry and is malformed).
+    throw new IOException("could not find " + entry + " in manifest");
+  }
+
+  /**
+   * A utility class that verifies jar entries as they are read.
+   */
+  private static class EntryInputStream extends FilterInputStream
+  {
+    private final JarFile jarfile;
+    private final long length;
+    private long pos;
+    private final ZipEntry entry;
+    private final byte[][] hashes;
+    private final MessageDigest[] md;
+    private boolean checked;
+
+    EntryInputStream(final ZipEntry entry,
+		     final InputStream in,
+		     final JarFile jar)
+      throws IOException
+    {
+      super(in);
+      this.entry = entry;
+      this.jarfile = jar;
+
+      length = entry.getSize();
+      pos = 0;
+      checked = false;
+
+      Attributes attr;
+      Manifest manifest = jarfile.getManifest();
+      if (manifest != null)
+	attr = manifest.getAttributes(entry.getName());
+      else
+	attr = null;
+      if (DEBUG)
+        debug("verifying entry " + entry + " attr=" + attr);
+      if (attr == null)
+        {
+          hashes = new byte[0][];
+          md = new MessageDigest[0];
+        }
+      else
+        {
+          List hashes = new LinkedList();
+          List md = new LinkedList();
+          for (Iterator it = attr.entrySet().iterator(); it.hasNext(); )
+            {
+              Map.Entry e = (Map.Entry) it.next();
+              String key = String.valueOf(e.getKey());
+              if (key == null)
+                continue;
+              if (!key.endsWith(DIGEST_KEY_SUFFIX))
+                continue;
+              hashes.add(Base64InputStream.decode((String) e.getValue()));
+              try
+                {
+                  md.add(MessageDigest.getInstance
+                         (key.substring(0, key.length() - DIGEST_KEY_SUFFIX.length())));
+                }
+              catch (NoSuchAlgorithmException nsae)
+                {
+                  IOException ioe = new IOException("no such message digest: " + key);
+                  ioe.initCause(nsae);
+                  throw ioe;
+                }
+            }
+          if (DEBUG)
+            debug("digests=" + md);
+          this.hashes = (byte[][]) hashes.toArray(new byte[hashes.size()][]);
+          this.md = (MessageDigest[]) md.toArray(new MessageDigest[md.size()]);
+        }
+    }
+
+    public boolean markSupported()
+    {
+      return false;
+    }
+
+    public void mark(int readLimit)
+    {
+    }
+
+    public void reset()
+    {
+    }
+
+    public int read() throws IOException
+    {
+      int b = super.read();
+      if (b == -1)
+        {
+          eof();
+          return -1;
+        }
+      for (int i = 0; i < md.length; i++)
+        md[i].update((byte) b);
+      pos++;
+      if (length > 0 && pos >= length)
+        eof();
+      return b;
+    }
+
+    public int read(byte[] buf, int off, int len) throws IOException
+    {
+      int count = super.read(buf, off, (int) Math.min(len, (length != 0
+                                                            ? length - pos
+                                                            : Integer.MAX_VALUE)));
+      if (count == -1 || (length > 0 && pos >= length))
+        {
+          eof();
+          return -1;
+        }
+      for (int i = 0; i < md.length; i++)
+        md[i].update(buf, off, count);
+      pos += count;
+      if (length != 0 && pos >= length)
+        eof();
+      return count;
+    }
+
+    public int read(byte[] buf) throws IOException
+    {
+      return read(buf, 0, buf.length);
+    }
+
+    public long skip(long bytes) throws IOException
+    {
+      byte[] b = new byte[1024];
+      long amount = 0;
+      while (amount < bytes)
+        {
+          int l = read(b, 0, (int) Math.min(b.length, bytes - amount));
+          if (l == -1)
+            break;
+          amount += l;
+        }
+      return amount;
+    }
+
+    private void eof() throws IOException
+    {
+      if (checked)
+        return;
+      checked = true;
+      for (int i = 0; i < md.length; i++)
+        {
+          byte[] hash = md[i].digest();
+          if (DEBUG)
+            debug("verifying " + md[i].getAlgorithm() + " expect="
+                  + new java.math.BigInteger(hashes[i]).toString(16)
+                  + " comp=" + new java.math.BigInteger(hash).toString(16));
+          if (!Arrays.equals(hash, hashes[i]))
+            {
+	      synchronized(jarfile)
+		{
+		  if (DEBUG)
+		    debug(entry + " could NOT be verified");
+		  jarfile.verified.put(entry.getName(), Boolean.FALSE);
+		}
+	      return;
+	      // XXX ??? what do we do here?
+	      // throw new ZipException("message digest mismatch");
+            }
+        }
+
+      synchronized(jarfile)
+	{
+	  if (DEBUG)
+	    debug(entry + " has been VERIFIED");
+	  jarfile.verified.put(entry.getName(), Boolean.TRUE);
+	}
+    }
+  }
 }