diff --git a/tools/signapk/SignApk.java b/tools/signapk/SignApk.java
index 1055704..adfe9a3 100644
--- a/tools/signapk/SignApk.java
+++ b/tools/signapk/SignApk.java
@@ -35,6 +35,7 @@
 import org.bouncycastle.util.encoders.Base64;
 
 import java.io.BufferedReader;
+import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
 import java.io.File;
@@ -96,7 +97,7 @@
                         Pattern.quote(JarFile.MANIFEST_NAME) + ")$");
 
     private static X509Certificate readPublicKey(File file)
-            throws IOException, GeneralSecurityException {
+        throws IOException, GeneralSecurityException {
         FileInputStream input = new FileInputStream(file);
         try {
             CertificateFactory cf = CertificateFactory.getInstance("X.509");
@@ -133,7 +134,7 @@
      * @param keyFile The file containing the private key
      */
     private static KeySpec decryptPrivateKey(byte[] encryptedPrivateKey, File keyFile)
-            throws GeneralSecurityException {
+        throws GeneralSecurityException {
         EncryptedPrivateKeyInfo epkInfo;
         try {
             epkInfo = new EncryptedPrivateKeyInfo(encryptedPrivateKey);
@@ -160,7 +161,7 @@
 
     /** Read a PKCS 8 format private key. */
     private static PrivateKey readPrivateKey(File file)
-            throws IOException, GeneralSecurityException {
+        throws IOException, GeneralSecurityException {
         DataInputStream input = new DataInputStream(new FileInputStream(file));
         try {
             byte[] bytes = new byte[(int) file.length()];
@@ -183,7 +184,7 @@
 
     /** Add the SHA1 of every file to the manifest, creating it if necessary. */
     private static Manifest addDigestsToManifest(JarFile jar)
-            throws IOException, GeneralSecurityException {
+        throws IOException, GeneralSecurityException {
         Manifest input = jar.getManifest();
         Manifest output = new Manifest();
         Attributes main = output.getMainAttributes();
@@ -301,8 +302,8 @@
 
         MessageDigest md = MessageDigest.getInstance("SHA1");
         PrintStream print = new PrintStream(
-                new DigestOutputStream(new ByteArrayOutputStream(), md),
-                true, "UTF-8");
+            new DigestOutputStream(new ByteArrayOutputStream(), md),
+            true, "UTF-8");
 
         // Digest of the entire manifest
         manifest.write(print);
@@ -339,31 +340,6 @@
         }
     }
 
-    private static class CMSByteArraySlice implements CMSTypedData {
-        private final ASN1ObjectIdentifier type;
-        private final byte[] data;
-        private final int offset;
-        private final int length;
-        public CMSByteArraySlice(byte[] data, int offset, int length) {
-            this.data = data;
-            this.offset = offset;
-            this.length = length;
-            this.type = new ASN1ObjectIdentifier(CMSObjectIdentifiers.data.getId());
-        }
-
-        public Object getContent() {
-            throw new UnsupportedOperationException();
-        }
-
-        public ASN1ObjectIdentifier getContentType() {
-            return type;
-        }
-
-        public void write(OutputStream out) throws IOException {
-            out.write(data, offset, length);
-        }
-    }
-
     /** Sign data and write the digital signature to 'out'. */
     private static void writeSignatureBlock(
         CMSTypedData data, X509Certificate publicKey, PrivateKey privateKey,
@@ -395,23 +371,170 @@
         dos.writeObject(asn1.readObject());
     }
 
-    private static void signWholeOutputFile(byte[] zipData,
-                                            OutputStream outputStream,
-                                            X509Certificate publicKey,
-                                            PrivateKey privateKey)
-        throws IOException,
-               CertificateEncodingException,
-               OperatorCreationException,
-               CMSException {
-        // For a zip with no archive comment, the
-        // end-of-central-directory record will be 22 bytes long, so
-        // we expect to find the EOCD marker 22 bytes from the end.
-        if (zipData[zipData.length-22] != 0x50 ||
-            zipData[zipData.length-21] != 0x4b ||
-            zipData[zipData.length-20] != 0x05 ||
-            zipData[zipData.length-19] != 0x06) {
-            throw new IllegalArgumentException("zip data already has an archive comment");
+    /**
+     * Copy all the files in a manifest from input to output.  We set
+     * the modification times in the output to a fixed time, so as to
+     * reduce variation in the output file and make incremental OTAs
+     * more efficient.
+     */
+    private static void copyFiles(Manifest manifest,
+                                  JarFile in, JarOutputStream out, long timestamp) throws IOException {
+        byte[] buffer = new byte[4096];
+        int num;
+
+        Map<String, Attributes> entries = manifest.getEntries();
+        ArrayList<String> names = new ArrayList<String>(entries.keySet());
+        Collections.sort(names);
+        for (String name : names) {
+            JarEntry inEntry = in.getJarEntry(name);
+            JarEntry outEntry = null;
+            if (inEntry.getMethod() == JarEntry.STORED) {
+                // Preserve the STORED method of the input entry.
+                outEntry = new JarEntry(inEntry);
+            } else {
+                // Create a new entry so that the compressed len is recomputed.
+                outEntry = new JarEntry(name);
+            }
+            outEntry.setTime(timestamp);
+            out.putNextEntry(outEntry);
+
+            InputStream data = in.getInputStream(inEntry);
+            while ((num = data.read(buffer)) > 0) {
+                out.write(buffer, 0, num);
+            }
+            out.flush();
         }
+    }
+
+    private static class WholeFileSignerOutputStream extends FilterOutputStream {
+        private boolean closing = false;
+        private ByteArrayOutputStream footer = new ByteArrayOutputStream();
+        private OutputStream tee;
+
+        public WholeFileSignerOutputStream(OutputStream out, OutputStream tee) {
+            super(out);
+            this.tee = tee;
+        }
+
+        public void notifyClosing() {
+            closing = true;
+        }
+
+        public void finish() throws IOException {
+            closing = false;
+
+            byte[] data = footer.toByteArray();
+            if (data.length < 2)
+                throw new IOException("Less than two bytes written to footer");
+            write(data, 0, data.length - 2);
+        }
+
+        public byte[] getTail() {
+            return footer.toByteArray();
+        }
+
+        @Override
+        public void write(byte[] b) throws IOException {
+            write(b, 0, b.length);
+        }
+
+        @Override
+        public void write(byte[] b, int off, int len) throws IOException {
+            if (closing) {
+                // if the jar is about to close, save the footer that will be written
+                footer.write(b, off, len);
+            }
+            else {
+                // write to both output streams. out is the CMSTypedData signer and tee is the file.
+                out.write(b, off, len);
+                tee.write(b, off, len);
+            }
+        }
+
+        @Override
+        public void write(int b) throws IOException {
+            if (closing) {
+                // if the jar is about to close, save the footer that will be written
+                footer.write(b);
+            }
+            else {
+                // write to both output streams. out is the CMSTypedData signer and tee is the file.
+                out.write(b);
+                tee.write(b);
+            }
+        }
+    }
+
+    private static class CMSSigner implements CMSTypedData {
+        private JarFile inputJar;
+        private File publicKeyFile;
+        private X509Certificate publicKey;
+        private PrivateKey privateKey;
+        private String outputFile;
+        private OutputStream outputStream;
+        private final ASN1ObjectIdentifier type;
+        private WholeFileSignerOutputStream signer;
+
+        public CMSSigner(JarFile inputJar, File publicKeyFile,
+                         X509Certificate publicKey, PrivateKey privateKey,
+                         OutputStream outputStream) {
+            this.inputJar = inputJar;
+            this.publicKeyFile = publicKeyFile;
+            this.publicKey = publicKey;
+            this.privateKey = privateKey;
+            this.outputStream = outputStream;
+            this.type = new ASN1ObjectIdentifier(CMSObjectIdentifiers.data.getId());
+        }
+
+        public Object getContent() {
+            throw new UnsupportedOperationException();
+        }
+
+        public ASN1ObjectIdentifier getContentType() {
+            return type;
+        }
+
+        public void write(OutputStream out) throws IOException {
+            try {
+                signer = new WholeFileSignerOutputStream(out, outputStream);
+                JarOutputStream outputJar = new JarOutputStream(signer);
+
+                Manifest manifest = addDigestsToManifest(inputJar);
+                signFile(manifest, inputJar,
+                         new X509Certificate[]{ publicKey },
+                         new PrivateKey[]{ privateKey },
+                         outputJar);
+                // Assume the certificate is valid for at least an hour.
+                long timestamp = publicKey.getNotBefore().getTime() + 3600L * 1000;
+                addOtacert(outputJar, publicKeyFile, timestamp, manifest);
+
+                signer.notifyClosing();
+                outputJar.close();
+                signer.finish();
+            }
+            catch (Exception e) {
+                throw new IOException(e);
+            }
+        }
+
+        public void writeSignatureBlock(ByteArrayOutputStream temp)
+            throws IOException,
+                   CertificateEncodingException,
+                   OperatorCreationException,
+                   CMSException {
+            SignApk.writeSignatureBlock(this, publicKey, privateKey, temp);
+        }
+
+        public WholeFileSignerOutputStream getSigner() {
+            return signer;
+        }
+    }
+
+    private static void signWholeFile(JarFile inputJar, File publicKeyFile,
+                                      X509Certificate publicKey, PrivateKey privateKey,
+                                      OutputStream outputStream) throws Exception {
+        CMSSigner cmsOut = new CMSSigner(inputJar, publicKeyFile,
+                                         publicKey, privateKey, outputStream);
 
         ByteArrayOutputStream temp = new ByteArrayOutputStream();
 
@@ -423,8 +546,20 @@
         temp.write(message);
         temp.write(0);
 
-        writeSignatureBlock(new CMSByteArraySlice(zipData, 0, zipData.length-2),
-                            publicKey, privateKey, temp);
+        cmsOut.writeSignatureBlock(temp);
+
+        byte[] zipData = cmsOut.getSigner().getTail();
+
+        // For a zip with no archive comment, the
+        // end-of-central-directory record will be 22 bytes long, so
+        // we expect to find the EOCD marker 22 bytes from the end.
+        if (zipData[zipData.length-22] != 0x50 ||
+            zipData[zipData.length-21] != 0x4b ||
+            zipData[zipData.length-20] != 0x05 ||
+            zipData[zipData.length-19] != 0x06) {
+            throw new IllegalArgumentException("zip data already has an archive comment");
+        }
+
         int total_size = temp.size() + 6;
         if (total_size > 0xffff) {
             throw new IllegalArgumentException("signature is too big for ZIP file comment");
@@ -458,44 +593,48 @@
             }
         }
 
-        outputStream.write(zipData, 0, zipData.length-2);
         outputStream.write(total_size & 0xff);
         outputStream.write((total_size >> 8) & 0xff);
         temp.writeTo(outputStream);
     }
 
-    /**
-     * Copy all the files in a manifest from input to output.  We set
-     * the modification times in the output to a fixed time, so as to
-     * reduce variation in the output file and make incremental OTAs
-     * more efficient.
-     */
-    private static void copyFiles(Manifest manifest,
-        JarFile in, JarOutputStream out, long timestamp) throws IOException {
-        byte[] buffer = new byte[4096];
-        int num;
+    private static void signFile(Manifest manifest, JarFile inputJar,
+                                 X509Certificate[] publicKey, PrivateKey[] privateKey,
+                                 JarOutputStream outputJar)
+        throws Exception {
+        // Assume the certificate is valid for at least an hour.
+        long timestamp = publicKey[0].getNotBefore().getTime() + 3600L * 1000;
 
-        Map<String, Attributes> entries = manifest.getEntries();
-        ArrayList<String> names = new ArrayList<String>(entries.keySet());
-        Collections.sort(names);
-        for (String name : names) {
-            JarEntry inEntry = in.getJarEntry(name);
-            JarEntry outEntry = null;
-            if (inEntry.getMethod() == JarEntry.STORED) {
-                // Preserve the STORED method of the input entry.
-                outEntry = new JarEntry(inEntry);
-            } else {
-                // Create a new entry so that the compressed len is recomputed.
-                outEntry = new JarEntry(name);
-            }
-            outEntry.setTime(timestamp);
-            out.putNextEntry(outEntry);
+        JarEntry je;
 
-            InputStream data = in.getInputStream(inEntry);
-            while ((num = data.read(buffer)) > 0) {
-                out.write(buffer, 0, num);
-            }
-            out.flush();
+        // Everything else
+        copyFiles(manifest, inputJar, outputJar, timestamp);
+
+        // MANIFEST.MF
+        je = new JarEntry(JarFile.MANIFEST_NAME);
+        je.setTime(timestamp);
+        outputJar.putNextEntry(je);
+        manifest.write(outputJar);
+
+        int numKeys = publicKey.length;
+        for (int k = 0; k < numKeys; ++k) {
+            // CERT.SF / CERT#.SF
+            je = new JarEntry(numKeys == 1 ? CERT_SF_NAME :
+                              (String.format(CERT_SF_MULTI_NAME, k)));
+            je.setTime(timestamp);
+            outputJar.putNextEntry(je);
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            writeSignatureFile(manifest, baos);
+            byte[] signedData = baos.toByteArray();
+            outputJar.write(signedData);
+
+            // CERT.RSA / CERT#.RSA
+            je = new JarEntry(numKeys == 1 ? CERT_RSA_NAME :
+                              (String.format(CERT_RSA_MULTI_NAME, k)));
+            je.setTime(timestamp);
+            outputJar.putNextEntry(je);
+            writeSignatureBlock(new CMSProcessableByteArray(signedData),
+                                publicKey[k], privateKey[k], outputJar);
         }
     }
 
@@ -531,7 +670,6 @@
         String outputFilename = args[args.length-1];
 
         JarFile inputJar = null;
-        JarOutputStream outputJar = null;
         FileOutputStream outputFile = null;
 
         try {
@@ -555,76 +693,26 @@
             }
             inputJar = new JarFile(new File(inputFilename), false);  // Don't verify.
 
-            OutputStream outputStream = null;
+            outputFile = new FileOutputStream(outputFilename);
+
+
             if (signWholeFile) {
-                outputStream = new ByteArrayOutputStream();
+                SignApk.signWholeFile(inputJar, firstPublicKeyFile,
+                                      publicKey[0], privateKey[0], outputFile);
             } else {
-                outputStream = outputFile = new FileOutputStream(outputFilename);
-            }
-            outputJar = new JarOutputStream(outputStream);
+                JarOutputStream outputJar = new JarOutputStream(outputFile);
 
-            // For signing .apks, use the maximum compression to make
-            // them as small as possible (since they live forever on
-            // the system partition).  For OTA packages, use the
-            // default compression level, which is much much faster
-            // and produces output that is only a tiny bit larger
-            // (~0.1% on full OTA packages I tested).
-            if (!signWholeFile) {
+                // For signing .apks, use the maximum compression to make
+                // them as small as possible (since they live forever on
+                // the system partition).  For OTA packages, use the
+                // default compression level, which is much much faster
+                // and produces output that is only a tiny bit larger
+                // (~0.1% on full OTA packages I tested).
                 outputJar.setLevel(9);
-            }
 
-            JarEntry je;
-
-            Manifest manifest = addDigestsToManifest(inputJar);
-
-            // Everything else
-            copyFiles(manifest, inputJar, outputJar, timestamp);
-
-            // otacert
-            if (signWholeFile) {
-                addOtacert(outputJar, firstPublicKeyFile, timestamp, manifest);
-            }
-
-            // MANIFEST.MF
-            je = new JarEntry(JarFile.MANIFEST_NAME);
-            je.setTime(timestamp);
-            outputJar.putNextEntry(je);
-            manifest.write(outputJar);
-
-            // In the case of multiple keys, all the .SF files will be
-            // identical, but as far as I can tell the jarsigner docs
-            // don't allow there to be just one copy in the zipfile;
-            // there hase to be one per .RSA file.
-
-            ByteArrayOutputStream baos = new ByteArrayOutputStream();
-            writeSignatureFile(manifest, baos);
-            byte[] signedData = baos.toByteArray();
-
-            for (int k = 0; k < numKeys; ++k) {
-                // CERT.SF / CERT#.SF
-                je = new JarEntry(numKeys == 1 ? CERT_SF_NAME :
-                                  (String.format(CERT_SF_MULTI_NAME, k)));
-                je.setTime(timestamp);
-                outputJar.putNextEntry(je);
-                outputJar.write(signedData);
-
-                // CERT.RSA / CERT#.RSA
-                je = new JarEntry(numKeys == 1 ? CERT_RSA_NAME :
-                                  (String.format(CERT_RSA_MULTI_NAME, k)));
-                je.setTime(timestamp);
-                outputJar.putNextEntry(je);
-                writeSignatureBlock(new CMSProcessableByteArray(signedData),
-                                    publicKey[k], privateKey[k], outputJar);
-            }
-
-            outputJar.close();
-            outputJar = null;
-            outputStream.flush();
-
-            if (signWholeFile) {
-                outputFile = new FileOutputStream(outputFilename);
-                signWholeOutputFile(((ByteArrayOutputStream)outputStream).toByteArray(),
-                                    outputFile, publicKey[0], privateKey[0]);
+                signFile(addDigestsToManifest(inputJar), inputJar,
+                         publicKey, privateKey, outputJar);
+                outputJar.close();
             }
         } catch (Exception e) {
             e.printStackTrace();