Update to APK Signature Scheme v2

app/signing/src/main/java/com/topjohnwu/signing/ApkSignerV2.java

@@ -0,0 +1,772 @@
+package com.topjohnwu.signing;
+
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.security.DigestException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.KeyFactory;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.Signature;
+import java.security.SignatureException;
+import java.security.cert.CertificateEncodingException;
+import java.security.cert.X509Certificate;
+import java.security.spec.AlgorithmParameterSpec;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.MGF1ParameterSpec;
+import java.security.spec.PSSParameterSpec;
+import java.security.spec.X509EncodedKeySpec;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * APK Signature Scheme v2 signer.
+ *
+ * <p>APK Signature Scheme v2 is a whole-file signature scheme which aims to protect every single
+ * bit of the APK, as opposed to the JAR Signature Scheme which protects only the names and
+ * uncompressed contents of ZIP entries.
+ */
+public abstract class ApkSignerV2 {
+    /*
+     * The two main goals of APK Signature Scheme v2 are:
+     * 1. Detect any unauthorized modifications to the APK. This is achieved by making the signature
+     *    cover every byte of the APK being signed.
+     * 2. Enable much faster signature and integrity verification. This is achieved by requiring
+     *    only a minimal amount of APK parsing before the signature is verified, thus completely
+     *    bypassing ZIP entry decompression and by making integrity verification parallelizable by
+     *    employing a hash tree.
+     *
+     * The generated signature block is wrapped into an APK Signing Block and inserted into the
+     * original APK immediately before the start of ZIP Central Directory. This is to ensure that
+     * JAR and ZIP parsers continue to work on the signed APK. The APK Signing Block is designed for
+     * extensibility. For example, a future signature scheme could insert its signatures there as
+     * well. The contract of the APK Signing Block is that all contents outside of the block must be
+     * protected by signatures inside the block.
+     */
+
+    public static final int SIGNATURE_RSA_PSS_WITH_SHA256 = 0x0101;
+    public static final int SIGNATURE_RSA_PSS_WITH_SHA512 = 0x0102;
+    public static final int SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA256 = 0x0103;
+    public static final int SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA512 = 0x0104;
+    public static final int SIGNATURE_ECDSA_WITH_SHA256 = 0x0201;
+    public static final int SIGNATURE_ECDSA_WITH_SHA512 = 0x0202;
+    public static final int SIGNATURE_DSA_WITH_SHA256 = 0x0301;
+    public static final int SIGNATURE_DSA_WITH_SHA512 = 0x0302;
+
+    /**
+     * {@code .SF} file header section attribute indicating that the APK is signed not just with
+     * JAR signature scheme but also with APK Signature Scheme v2 or newer. This attribute
+     * facilitates v2 signature stripping detection.
+     *
+     * <p>The attribute contains a comma-separated set of signature scheme IDs.
+     */
+    public static final String SF_ATTRIBUTE_ANDROID_APK_SIGNED_NAME = "X-Android-APK-Signed";
+    public static final String SF_ATTRIBUTE_ANDROID_APK_SIGNED_VALUE = "2";
+
+    private static final int CONTENT_DIGEST_CHUNKED_SHA256 = 0;
+    private static final int CONTENT_DIGEST_CHUNKED_SHA512 = 1;
+
+    private static final int CONTENT_DIGESTED_CHUNK_MAX_SIZE_BYTES = 1024 * 1024;
+
+    private static final byte[] APK_SIGNING_BLOCK_MAGIC =
+          new byte[] {
+              0x41, 0x50, 0x4b, 0x20, 0x53, 0x69, 0x67, 0x20,
+              0x42, 0x6c, 0x6f, 0x63, 0x6b, 0x20, 0x34, 0x32,
+          };
+    private static final int APK_SIGNATURE_SCHEME_V2_BLOCK_ID = 0x7109871a;
+
+    private ApkSignerV2() {}
+
+    /**
+     * Signer configuration.
+     */
+    public static final class SignerConfig {
+        /** Private key. */
+        public PrivateKey privateKey;
+
+        /**
+         * Certificates, with the first certificate containing the public key corresponding to
+         * {@link #privateKey}.
+         */
+        public List<X509Certificate> certificates;
+
+        /**
+         * List of signature algorithms with which to sign (see {@code SIGNATURE_...} constants).
+         */
+        public List<Integer> signatureAlgorithms;
+    }
+
+    /**
+     * Signs the provided APK using APK Signature Scheme v2 and returns the signed APK as a list of
+     * consecutive chunks.
+     *
+     * <p>NOTE: To enable APK signature verifier to detect v2 signature stripping, header sections
+     * of META-INF/*.SF files of APK being signed must contain the
+     * {@code X-Android-APK-Signed: true} attribute.
+     *
+     * @param inputApk contents of the APK to be signed. The APK starts at the current position
+     *        of the buffer and ends at the limit of the buffer.
+     * @param signerConfigs signer configurations, one for each signer.
+     *
+     * @throws ApkParseException if the APK cannot be parsed.
+     * @throws InvalidKeyException if a signing key is not suitable for this signature scheme or
+     *         cannot be used in general.
+     * @throws SignatureException if an error occurs when computing digests of generating
+     *         signatures.
+     */
+    public static ByteBuffer[] sign(
+            ByteBuffer inputApk,
+            List<SignerConfig> signerConfigs)
+                    throws ApkParseException, InvalidKeyException, SignatureException {
+        // Slice/create a view in the inputApk to make sure that:
+        // 1. inputApk is what's between position and limit of the original inputApk, and
+        // 2. changes to position, limit, and byte order are not reflected in the original.
+        ByteBuffer originalInputApk = inputApk;
+        inputApk = originalInputApk.slice();
+        inputApk.order(ByteOrder.LITTLE_ENDIAN);
+
+        // Locate ZIP End of Central Directory (EoCD), Central Directory, and check that Central
+        // Directory is immediately followed by the ZIP End of Central Directory.
+        int eocdOffset = ZipUtils.findZipEndOfCentralDirectoryRecord(inputApk);
+        if (eocdOffset == -1) {
+            throw new ApkParseException("Failed to locate ZIP End of Central Directory");
+        }
+        if (ZipUtils.isZip64EndOfCentralDirectoryLocatorPresent(inputApk, eocdOffset)) {
+            throw new ApkParseException("ZIP64 format not supported");
+        }
+        inputApk.position(eocdOffset);
+        long centralDirSizeLong = ZipUtils.getZipEocdCentralDirectorySizeBytes(inputApk);
+        if (centralDirSizeLong > Integer.MAX_VALUE) {
+            throw new ApkParseException(
+                    "ZIP Central Directory size out of range: " + centralDirSizeLong);
+        }
+        int centralDirSize = (int) centralDirSizeLong;
+        long centralDirOffsetLong = ZipUtils.getZipEocdCentralDirectoryOffset(inputApk);
+        if (centralDirOffsetLong > Integer.MAX_VALUE) {
+            throw new ApkParseException(
+                    "ZIP Central Directory offset in file out of range: " + centralDirOffsetLong);
+        }
+        int centralDirOffset = (int) centralDirOffsetLong;
+        int expectedEocdOffset = centralDirOffset + centralDirSize;
+        if (expectedEocdOffset < centralDirOffset) {
+            throw new ApkParseException(
+                    "ZIP Central Directory extent too large. Offset: " + centralDirOffset
+                            + ", size: " + centralDirSize);
+        }
+        if (eocdOffset != expectedEocdOffset) {
+            throw new ApkParseException(
+                    "ZIP Central Directory not immeiately followed by ZIP End of"
+                            + " Central Directory. CD end: " + expectedEocdOffset
+                            + ", EoCD start: " + eocdOffset);
+        }
+
+        // Create ByteBuffers holding the contents of everything before ZIP Central Directory,
+        // ZIP Central Directory, and ZIP End of Central Directory.
+        inputApk.clear();
+        ByteBuffer beforeCentralDir = getByteBuffer(inputApk, centralDirOffset);
+        ByteBuffer centralDir = getByteBuffer(inputApk, eocdOffset - centralDirOffset);
+        // Create a copy of End of Central Directory because we'll need modify its contents later.
+        byte[] eocdBytes = new byte[inputApk.remaining()];
+        inputApk.get(eocdBytes);
+        ByteBuffer eocd = ByteBuffer.wrap(eocdBytes);
+        eocd.order(inputApk.order());
+
+        // Figure which which digests to use for APK contents.
+        Set<Integer> contentDigestAlgorithms = new HashSet<>();
+        for (SignerConfig signerConfig : signerConfigs) {
+            for (int signatureAlgorithm : signerConfig.signatureAlgorithms) {
+                contentDigestAlgorithms.add(
+                        getSignatureAlgorithmContentDigestAlgorithm(signatureAlgorithm));
+            }
+        }
+
+        // Compute digests of APK contents.
+        Map<Integer, byte[]> contentDigests; // digest algorithm ID -> digest
+        try {
+            contentDigests =
+                    computeContentDigests(
+                            contentDigestAlgorithms,
+                            new ByteBuffer[] {beforeCentralDir, centralDir, eocd});
+        } catch (DigestException e) {
+            throw new SignatureException("Failed to compute digests of APK", e);
+        }
+
+        // Sign the digests and wrap the signatures and signer info into an APK Signing Block.
+        ByteBuffer apkSigningBlock =
+                ByteBuffer.wrap(generateApkSigningBlock(signerConfigs, contentDigests));
+
+        // Update Central Directory Offset in End of Central Directory Record. Central Directory
+        // follows the APK Signing Block and thus is shifted by the size of the APK Signing Block.
+        centralDirOffset += apkSigningBlock.remaining();
+        eocd.clear();
+        ZipUtils.setZipEocdCentralDirectoryOffset(eocd, centralDirOffset);
+
+        // Follow the Java NIO pattern for ByteBuffer whose contents have been consumed.
+        originalInputApk.position(originalInputApk.limit());
+
+        // Reset positions (to 0) and limits (to capacity) in the ByteBuffers below to follow the
+        // Java NIO pattern for ByteBuffers which are ready for their contents to be read by caller.
+        // Contrary to the name, this does not clear the contents of these ByteBuffer.
+        beforeCentralDir.clear();
+        centralDir.clear();
+        eocd.clear();
+
+        // Insert APK Signing Block immediately before the ZIP Central Directory.
+        return new ByteBuffer[] {
+            beforeCentralDir,
+            apkSigningBlock,
+            centralDir,
+            eocd,
+        };
+    }
+
+    private static Map<Integer, byte[]> computeContentDigests(
+            Set<Integer> digestAlgorithms,
+            ByteBuffer[] contents) throws DigestException {
+        // For each digest algorithm the result is computed as follows:
+        // 1. Each segment of contents is split into consecutive chunks of 1 MB in size.
+        //    The final chunk will be shorter iff the length of segment is not a multiple of 1 MB.
+        //    No chunks are produced for empty (zero length) segments.
+        // 2. The digest of each chunk is computed over the concatenation of byte 0xa5, the chunk's
+        //    length in bytes (uint32 little-endian) and the chunk's contents.
+        // 3. The output digest is computed over the concatenation of the byte 0x5a, the number of
+        //    chunks (uint32 little-endian) and the concatenation of digests of chunks of all
+        //    segments in-order.
+
+        int chunkCount = 0;
+        for (ByteBuffer input : contents) {
+            chunkCount += getChunkCount(input.remaining(), CONTENT_DIGESTED_CHUNK_MAX_SIZE_BYTES);
+        }
+
+        final Map<Integer, byte[]> digestsOfChunks = new HashMap<>(digestAlgorithms.size());
+        for (int digestAlgorithm : digestAlgorithms) {
+            int digestOutputSizeBytes = getContentDigestAlgorithmOutputSizeBytes(digestAlgorithm);
+            byte[] concatenationOfChunkCountAndChunkDigests =
+                    new byte[5 + chunkCount * digestOutputSizeBytes];
+            concatenationOfChunkCountAndChunkDigests[0] = 0x5a;
+            setUnsignedInt32LittleEngian(
+                    chunkCount, concatenationOfChunkCountAndChunkDigests, 1);
+            digestsOfChunks.put(digestAlgorithm, concatenationOfChunkCountAndChunkDigests);
+        }
+
+        int chunkIndex = 0;
+        byte[] chunkContentPrefix = new byte[5];
+        chunkContentPrefix[0] = (byte) 0xa5;
+        // Optimization opportunity: digests of chunks can be computed in parallel.
+        for (ByteBuffer input : contents) {
+            while (input.hasRemaining()) {
+                int chunkSize =
+                        Math.min(input.remaining(), CONTENT_DIGESTED_CHUNK_MAX_SIZE_BYTES);
+                final ByteBuffer chunk = getByteBuffer(input, chunkSize);
+                for (int digestAlgorithm : digestAlgorithms) {
+                    String jcaAlgorithmName =
+                            getContentDigestAlgorithmJcaDigestAlgorithm(digestAlgorithm);
+                    MessageDigest md;
+                    try {
+                        md = MessageDigest.getInstance(jcaAlgorithmName);
+                    } catch (NoSuchAlgorithmException e) {
+                        throw new DigestException(
+                                jcaAlgorithmName + " MessageDigest not supported", e);
+                    }
+                    // Reset position to 0 and limit to capacity. Position would've been modified
+                    // by the preceding iteration of this loop. NOTE: Contrary to the method name,
+                    // this does not modify the contents of the chunk.
+                    chunk.clear();
+                    setUnsignedInt32LittleEngian(chunk.remaining(), chunkContentPrefix, 1);
+                    md.update(chunkContentPrefix);
+                    md.update(chunk);
+                    byte[] concatenationOfChunkCountAndChunkDigests =
+                            digestsOfChunks.get(digestAlgorithm);
+                    int expectedDigestSizeBytes =
+                            getContentDigestAlgorithmOutputSizeBytes(digestAlgorithm);
+                    int actualDigestSizeBytes =
+                            md.digest(
+                                    concatenationOfChunkCountAndChunkDigests,
+                                    5 + chunkIndex * expectedDigestSizeBytes,
+                                    expectedDigestSizeBytes);
+                    if (actualDigestSizeBytes != expectedDigestSizeBytes) {
+                        throw new DigestException(
+                                "Unexpected output size of " + md.getAlgorithm()
+                                        + " digest: " + actualDigestSizeBytes);
+                    }
+                }
+                chunkIndex++;
+            }
+        }
+
+        Map<Integer, byte[]> result = new HashMap<>(digestAlgorithms.size());
+        for (Map.Entry<Integer, byte[]> entry : digestsOfChunks.entrySet()) {
+            int digestAlgorithm = entry.getKey();
+            byte[] concatenationOfChunkCountAndChunkDigests = entry.getValue();
+            String jcaAlgorithmName = getContentDigestAlgorithmJcaDigestAlgorithm(digestAlgorithm);
+            MessageDigest md;
+            try {
+                md = MessageDigest.getInstance(jcaAlgorithmName);
+            } catch (NoSuchAlgorithmException e) {
+                throw new DigestException(jcaAlgorithmName + " MessageDigest not supported", e);
+            }
+            result.put(digestAlgorithm, md.digest(concatenationOfChunkCountAndChunkDigests));
+        }
+        return result;
+    }
+
+    private static int getChunkCount(int inputSize, int chunkSize) {
+        return (inputSize + chunkSize - 1) / chunkSize;
+    }
+
+    private static void setUnsignedInt32LittleEngian(int value, byte[] result, int offset) {
+        result[offset] = (byte) (value & 0xff);
+        result[offset + 1] = (byte) ((value >> 8) & 0xff);
+        result[offset + 2] = (byte) ((value >> 16) & 0xff);
+        result[offset + 3] = (byte) ((value >> 24) & 0xff);
+    }
+
+    private static byte[] generateApkSigningBlock(
+            List<SignerConfig> signerConfigs,
+            Map<Integer, byte[]> contentDigests) throws InvalidKeyException, SignatureException {
+        byte[] apkSignatureSchemeV2Block =
+                generateApkSignatureSchemeV2Block(signerConfigs, contentDigests);
+        return generateApkSigningBlock(apkSignatureSchemeV2Block);
+    }
+
+    private static byte[] generateApkSigningBlock(byte[] apkSignatureSchemeV2Block) {
+        // FORMAT:
+        // uint64:  size (excluding this field)
+        // repeated ID-value pairs:
+        //     uint64:           size (excluding this field)
+        //     uint32:           ID
+        //     (size - 4) bytes: value
+        // uint64:  size (same as the one above)
+        // uint128: magic
+
+        int resultSize =
+                8 // size
+                + 8 + 4 + apkSignatureSchemeV2Block.length // v2Block as ID-value pair
+                + 8 // size
+                + 16 // magic
+                ;
+        ByteBuffer result = ByteBuffer.allocate(resultSize);
+        result.order(ByteOrder.LITTLE_ENDIAN);
+        long blockSizeFieldValue = resultSize - 8;
+        result.putLong(blockSizeFieldValue);
+
+        long pairSizeFieldValue = 4 + apkSignatureSchemeV2Block.length;
+        result.putLong(pairSizeFieldValue);
+        result.putInt(APK_SIGNATURE_SCHEME_V2_BLOCK_ID);
+        result.put(apkSignatureSchemeV2Block);
+
+        result.putLong(blockSizeFieldValue);
+        result.put(APK_SIGNING_BLOCK_MAGIC);
+
+        return result.array();
+    }
+
+    private static byte[] generateApkSignatureSchemeV2Block(
+            List<SignerConfig> signerConfigs,
+            Map<Integer, byte[]> contentDigests) throws InvalidKeyException, SignatureException {
+        // FORMAT:
+        // * length-prefixed sequence of length-prefixed signer blocks.
+
+        List<byte[]> signerBlocks = new ArrayList<>(signerConfigs.size());
+        int signerNumber = 0;
+        for (SignerConfig signerConfig : signerConfigs) {
+            signerNumber++;
+            byte[] signerBlock;
+            try {
+                signerBlock = generateSignerBlock(signerConfig, contentDigests);
+            } catch (InvalidKeyException e) {
+                throw new InvalidKeyException("Signer #" + signerNumber + " failed", e);
+            } catch (SignatureException e) {
+                throw new SignatureException("Signer #" + signerNumber + " failed", e);
+            }
+            signerBlocks.add(signerBlock);
+        }
+
+        return encodeAsSequenceOfLengthPrefixedElements(
+                new byte[][] {
+                    encodeAsSequenceOfLengthPrefixedElements(signerBlocks),
+                });
+    }
+
+    private static byte[] generateSignerBlock(
+            SignerConfig signerConfig,
+            Map<Integer, byte[]> contentDigests) throws InvalidKeyException, SignatureException {
+        if (signerConfig.certificates.isEmpty()) {
+            throw new SignatureException("No certificates configured for signer");
+        }
+        PublicKey publicKey = signerConfig.certificates.get(0).getPublicKey();
+
+        byte[] encodedPublicKey = encodePublicKey(publicKey);
+
+        V2SignatureSchemeBlock.SignedData signedData = new V2SignatureSchemeBlock.SignedData();
+        try {
+            signedData.certificates = encodeCertificates(signerConfig.certificates);
+        } catch (CertificateEncodingException e) {
+            throw new SignatureException("Failed to encode certificates", e);
+        }
+
+        List<Pair<Integer, byte[]>> digests =
+                new ArrayList<>(signerConfig.signatureAlgorithms.size());
+        for (int signatureAlgorithm : signerConfig.signatureAlgorithms) {
+            int contentDigestAlgorithm =
+                    getSignatureAlgorithmContentDigestAlgorithm(signatureAlgorithm);
+            byte[] contentDigest = contentDigests.get(contentDigestAlgorithm);
+            if (contentDigest == null) {
+                throw new RuntimeException(
+                        getContentDigestAlgorithmJcaDigestAlgorithm(contentDigestAlgorithm)
+                        + " content digest for "
+                        + getSignatureAlgorithmJcaSignatureAlgorithm(signatureAlgorithm)
+                        + " not computed");
+            }
+            digests.add(Pair.create(signatureAlgorithm, contentDigest));
+        }
+        signedData.digests = digests;
+
+        V2SignatureSchemeBlock.Signer signer = new V2SignatureSchemeBlock.Signer();
+        // FORMAT:
+        // * length-prefixed sequence of length-prefixed digests:
+        //   * uint32: signature algorithm ID
+        //   * length-prefixed bytes: digest of contents
+        // * length-prefixed sequence of certificates:
+        //   * length-prefixed bytes: X.509 certificate (ASN.1 DER encoded).
+        // * length-prefixed sequence of length-prefixed additional attributes:
+        //   * uint32: ID
+        //   * (length - 4) bytes: value
+        signer.signedData = encodeAsSequenceOfLengthPrefixedElements(new byte[][] {
+            encodeAsSequenceOfLengthPrefixedPairsOfIntAndLengthPrefixedBytes(signedData.digests),
+            encodeAsSequenceOfLengthPrefixedElements(signedData.certificates),
+            // additional attributes
+            new byte[0],
+        });
+        signer.publicKey = encodedPublicKey;
+        signer.signatures = new ArrayList<>();
+        for (int signatureAlgorithm : signerConfig.signatureAlgorithms) {
+            Pair<String, ? extends AlgorithmParameterSpec> signatureParams =
+                    getSignatureAlgorithmJcaSignatureAlgorithm(signatureAlgorithm);
+            String jcaSignatureAlgorithm = signatureParams.getFirst();
+            AlgorithmParameterSpec jcaSignatureAlgorithmParams = signatureParams.getSecond();
+            byte[] signatureBytes;
+            try {
+                Signature signature = Signature.getInstance(jcaSignatureAlgorithm);
+                signature.initSign(signerConfig.privateKey);
+                if (jcaSignatureAlgorithmParams != null) {
+                    signature.setParameter(jcaSignatureAlgorithmParams);
+                }
+                signature.update(signer.signedData);
+                signatureBytes = signature.sign();
+            } catch (InvalidKeyException e) {
+                throw new InvalidKeyException("Failed sign using " + jcaSignatureAlgorithm, e);
+            } catch (NoSuchAlgorithmException | InvalidAlgorithmParameterException
+                    | SignatureException e) {
+                throw new SignatureException("Failed sign using " + jcaSignatureAlgorithm, e);
+            }
+
+            try {
+                Signature signature = Signature.getInstance(jcaSignatureAlgorithm);
+                signature.initVerify(publicKey);
+                if (jcaSignatureAlgorithmParams != null) {
+                    signature.setParameter(jcaSignatureAlgorithmParams);
+                }
+                signature.update(signer.signedData);
+                if (!signature.verify(signatureBytes)) {
+                    throw new SignatureException("Signature did not verify");
+                }
+            } catch (InvalidKeyException e) {
+                throw new InvalidKeyException("Failed to verify generated " + jcaSignatureAlgorithm
+                        + " signature using public key from certificate", e);
+            } catch (NoSuchAlgorithmException | InvalidAlgorithmParameterException
+                    | SignatureException e) {
+                throw new SignatureException("Failed to verify generated " + jcaSignatureAlgorithm
+                        + " signature using public key from certificate", e);
+            }
+
+            signer.signatures.add(Pair.create(signatureAlgorithm, signatureBytes));
+        }
+
+        // FORMAT:
+        // * length-prefixed signed data
+        // * length-prefixed sequence of length-prefixed signatures:
+        //   * uint32: signature algorithm ID
+        //   * length-prefixed bytes: signature of signed data
+        // * length-prefixed bytes: public key (X.509 SubjectPublicKeyInfo, ASN.1 DER encoded)
+        return encodeAsSequenceOfLengthPrefixedElements(
+                new byte[][] {
+                    signer.signedData,
+                    encodeAsSequenceOfLengthPrefixedPairsOfIntAndLengthPrefixedBytes(
+                            signer.signatures),
+                    signer.publicKey,
+                });
+    }
+
+    private static final class V2SignatureSchemeBlock {
+        private static final class Signer {
+            public byte[] signedData;
+            public List<Pair<Integer, byte[]>> signatures;
+            public byte[] publicKey;
+        }
+
+        private static final class SignedData {
+            public List<Pair<Integer, byte[]>> digests;
+            public List<byte[]> certificates;
+        }
+    }
+
+    private static byte[] encodePublicKey(PublicKey publicKey) throws InvalidKeyException {
+        byte[] encodedPublicKey = null;
+        if ("X.509".equals(publicKey.getFormat())) {
+            encodedPublicKey = publicKey.getEncoded();
+        }
+        if (encodedPublicKey == null) {
+            try {
+                encodedPublicKey =
+                        KeyFactory.getInstance(publicKey.getAlgorithm())
+                                .getKeySpec(publicKey, X509EncodedKeySpec.class)
+                                .getEncoded();
+            } catch (NoSuchAlgorithmException | InvalidKeySpecException e) {
+                throw new InvalidKeyException(
+                        "Failed to obtain X.509 encoded form of public key " + publicKey
+                                + " of class " + publicKey.getClass().getName(),
+                        e);
+            }
+        }
+        if ((encodedPublicKey == null) || (encodedPublicKey.length == 0)) {
+            throw new InvalidKeyException(
+                    "Failed to obtain X.509 encoded form of public key " + publicKey
+                            + " of class " + publicKey.getClass().getName());
+        }
+        return encodedPublicKey;
+    }
+
+    public static List<byte[]> encodeCertificates(List<X509Certificate> certificates)
+            throws CertificateEncodingException {
+        List<byte[]> result = new ArrayList<>();
+        for (X509Certificate certificate : certificates) {
+            result.add(certificate.getEncoded());
+        }
+        return result;
+    }
+
+    private static byte[] encodeAsSequenceOfLengthPrefixedElements(List<byte[]> sequence) {
+        return encodeAsSequenceOfLengthPrefixedElements(
+                sequence.toArray(new byte[sequence.size()][]));
+    }
+
+    private static byte[] encodeAsSequenceOfLengthPrefixedElements(byte[][] sequence) {
+        int payloadSize = 0;
+        for (byte[] element : sequence) {
+            payloadSize += 4 + element.length;
+        }
+        ByteBuffer result = ByteBuffer.allocate(payloadSize);
+        result.order(ByteOrder.LITTLE_ENDIAN);
+        for (byte[] element : sequence) {
+            result.putInt(element.length);
+            result.put(element);
+        }
+        return result.array();
+      }
+
+    private static byte[] encodeAsSequenceOfLengthPrefixedPairsOfIntAndLengthPrefixedBytes(
+            List<Pair<Integer, byte[]>> sequence) {
+        int resultSize = 0;
+        for (Pair<Integer, byte[]> element : sequence) {
+            resultSize += 12 + element.getSecond().length;
+        }
+        ByteBuffer result = ByteBuffer.allocate(resultSize);
+        result.order(ByteOrder.LITTLE_ENDIAN);
+        for (Pair<Integer, byte[]> element : sequence) {
+            byte[] second = element.getSecond();
+            result.putInt(8 + second.length);
+            result.putInt(element.getFirst());
+            result.putInt(second.length);
+            result.put(second);
+        }
+        return result.array();
+    }
+
+    /**
+     * Relative <em>get</em> method for reading {@code size} number of bytes from the current
+     * position of this buffer.
+     *
+     * <p>This method reads the next {@code size} bytes at this buffer's current position,
+     * returning them as a {@code ByteBuffer} with start set to 0, limit and capacity set to
+     * {@code size}, byte order set to this buffer's byte order; and then increments the position by
+     * {@code size}.
+     */
+    private static ByteBuffer getByteBuffer(ByteBuffer source, int size) {
+        if (size < 0) {
+            throw new IllegalArgumentException("size: " + size);
+        }
+        int originalLimit = source.limit();
+        int position = source.position();
+        int limit = position + size;
+        if ((limit < position) || (limit > originalLimit)) {
+            throw new BufferUnderflowException();
+        }
+        source.limit(limit);
+        try {
+            ByteBuffer result = source.slice();
+            result.order(source.order());
+            source.position(limit);
+            return result;
+        } finally {
+            source.limit(originalLimit);
+        }
+    }
+
+    private static Pair<String, ? extends AlgorithmParameterSpec>
+            getSignatureAlgorithmJcaSignatureAlgorithm(int sigAlgorithm) {
+        switch (sigAlgorithm) {
+            case SIGNATURE_RSA_PSS_WITH_SHA256:
+                return Pair.create(
+                        "SHA256withRSA/PSS",
+                        new PSSParameterSpec(
+                                "SHA-256", "MGF1", MGF1ParameterSpec.SHA256, 256 / 8, 1));
+            case SIGNATURE_RSA_PSS_WITH_SHA512:
+                return Pair.create(
+                        "SHA512withRSA/PSS",
+                        new PSSParameterSpec(
+                                "SHA-512", "MGF1", MGF1ParameterSpec.SHA512, 512 / 8, 1));
+            case SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA256:
+                return Pair.create("SHA256withRSA", null);
+            case SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA512:
+                return Pair.create("SHA512withRSA", null);
+            case SIGNATURE_ECDSA_WITH_SHA256:
+                return Pair.create("SHA256withECDSA", null);
+            case SIGNATURE_ECDSA_WITH_SHA512:
+                return Pair.create("SHA512withECDSA", null);
+            case SIGNATURE_DSA_WITH_SHA256:
+                return Pair.create("SHA256withDSA", null);
+            case SIGNATURE_DSA_WITH_SHA512:
+                return Pair.create("SHA512withDSA", null);
+            default:
+                throw new IllegalArgumentException(
+                        "Unknown signature algorithm: 0x"
+                                + Long.toHexString(sigAlgorithm & 0xffffffff));
+        }
+    }
+
+    private static int getSignatureAlgorithmContentDigestAlgorithm(int sigAlgorithm) {
+        switch (sigAlgorithm) {
+            case SIGNATURE_RSA_PSS_WITH_SHA256:
+            case SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA256:
+            case SIGNATURE_ECDSA_WITH_SHA256:
+            case SIGNATURE_DSA_WITH_SHA256:
+                return CONTENT_DIGEST_CHUNKED_SHA256;
+            case SIGNATURE_RSA_PSS_WITH_SHA512:
+            case SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA512:
+            case SIGNATURE_ECDSA_WITH_SHA512:
+            case SIGNATURE_DSA_WITH_SHA512:
+                return CONTENT_DIGEST_CHUNKED_SHA512;
+            default:
+                throw new IllegalArgumentException(
+                        "Unknown signature algorithm: 0x"
+                                + Long.toHexString(sigAlgorithm & 0xffffffff));
+        }
+    }
+
+    private static String getContentDigestAlgorithmJcaDigestAlgorithm(int digestAlgorithm) {
+        switch (digestAlgorithm) {
+            case CONTENT_DIGEST_CHUNKED_SHA256:
+                return "SHA-256";
+            case CONTENT_DIGEST_CHUNKED_SHA512:
+                return "SHA-512";
+            default:
+                throw new IllegalArgumentException(
+                        "Unknown content digest algorthm: " + digestAlgorithm);
+        }
+    }
+
+    private static int getContentDigestAlgorithmOutputSizeBytes(int digestAlgorithm) {
+        switch (digestAlgorithm) {
+            case CONTENT_DIGEST_CHUNKED_SHA256:
+                return 256 / 8;
+            case CONTENT_DIGEST_CHUNKED_SHA512:
+                return 512 / 8;
+            default:
+                throw new IllegalArgumentException(
+                        "Unknown content digest algorthm: " + digestAlgorithm);
+        }
+    }
+
+    /**
+     * Indicates that APK file could not be parsed.
+     */
+    public static class ApkParseException extends Exception {
+        private static final long serialVersionUID = 1L;
+
+        public ApkParseException(String message) {
+            super(message);
+        }
+
+        public ApkParseException(String message, Throwable cause) {
+            super(message, cause);
+        }
+    }
+
+    /**
+     * Pair of two elements.
+     */
+    private static class Pair<A, B> {
+        private final A mFirst;
+        private final B mSecond;
+
+        private Pair(A first, B second) {
+            mFirst = first;
+            mSecond = second;
+        }
+
+        public static <A, B> Pair<A, B> create(A first, B second) {
+            return new Pair<>(first, second);
+        }
+
+        public A getFirst() {
+            return mFirst;
+        }
+
+        public B getSecond() {
+            return mSecond;
+        }
+
+        @Override
+        public int hashCode() {
+            final int prime = 31;
+            int result = 1;
+            result = prime * result + ((mFirst == null) ? 0 : mFirst.hashCode());
+            result = prime * result + ((mSecond == null) ? 0 : mSecond.hashCode());
+            return result;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj == null) {
+                return false;
+            }
+            if (getClass() != obj.getClass()) {
+                return false;
+            }
+            @SuppressWarnings("rawtypes")
+            Pair other = (Pair) obj;
+            if (mFirst == null) {
+                if (other.mFirst != null) {
+                    return false;
+                }
+            } else if (!mFirst.equals(other.mFirst)) {
+                return false;
+            }
+            if (mSecond == null) {
+                return other.mSecond == null;
+            } else return mSecond.equals(other.mSecond);
+        }
+    }
+}

app/signing/src/main/java/com/topjohnwu/signing/SignApk.java

@@ -2,9 +2,7 @@ package com.topjohnwu.signing;
 
 import org.bouncycastle.asn1.ASN1Encoding;
 import org.bouncycastle.asn1.ASN1InputStream;
-import org.bouncycastle.asn1.ASN1ObjectIdentifier;
 import org.bouncycastle.asn1.ASN1OutputStream;
-import org.bouncycastle.asn1.cms.CMSObjectIdentifiers;
 import org.bouncycastle.cert.jcajce.JcaCertStore;
 import org.bouncycastle.cms.CMSException;
 import org.bouncycastle.cms.CMSProcessableByteArray;
@@ -12,34 +10,38 @@ import org.bouncycastle.cms.CMSSignedData;
 import org.bouncycastle.cms.CMSSignedDataGenerator;
 import org.bouncycastle.cms.CMSTypedData;
 import org.bouncycastle.cms.jcajce.JcaSignerInfoGeneratorBuilder;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
 import org.bouncycastle.operator.ContentSigner;
 import org.bouncycastle.operator.OperatorCreationException;
 import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
 import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;
 import org.bouncycastle.util.encoders.Base64;
 
-import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
-import java.io.File;
-import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.FilterOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.PrintStream;
-import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
 import java.security.DigestOutputStream;
 import java.security.GeneralSecurityException;
+import java.security.InvalidKeyException;
 import java.security.MessageDigest;
 import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.Security;
 import java.security.cert.CertificateEncodingException;
 import java.security.cert.X509Certificate;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.TimeZone;
 import java.util.TreeMap;
 import java.util.jar.Attributes;
 import java.util.jar.JarEntry;
@@ -49,72 +51,28 @@ import java.util.jar.Manifest;
 import java.util.regex.Pattern;
 
 /*
-* Modified from from AOSP
-* https://android.googlesource.com/platform/build/+/refs/heads/marshmallow-release/tools/signapk/SignApk.java
-* */
-
-public class SignAPK {
+ * Modified from from AOSP
+ * https://android.googlesource.com/platform/build/+/refs/tags/android-7.1.2_r39/tools/signapk/src/com/android/signapk/SignApk.java
+ * */
 
+public class SignApk {
     private static final String CERT_SF_NAME = "META-INF/CERT.SF";
     private static final String CERT_SIG_NAME = "META-INF/CERT.%s";
+    private static final String CERT_SF_MULTI_NAME = "META-INF/CERT%d.SF";
+    private static final String CERT_SIG_MULTI_NAME = "META-INF/CERT%d.%s";
 
     // bitmasks for which hash algorithms we need the manifest to include.
     private static final int USE_SHA1 = 1;
     private static final int USE_SHA256 = 2;
 
-    public static void signAndAdjust(X509Certificate cert, PrivateKey key,
-                                     JarMap input, OutputStream output) throws Exception {
-        File temp1 = File.createTempFile("signAPK", null);
-        File temp2 = File.createTempFile("signAPK", null);
-
-        try {
-            try (OutputStream out = new BufferedOutputStream(new FileOutputStream(temp1))) {
-                sign(cert, key, input, out, false);
-            }
-
-            ZipAdjust.adjust(temp1, temp2);
-
-            try (JarMap map = JarMap.open(temp2, false)) {
-                sign(cert, key, map, output, true);
-            }
-        } finally {
-            temp1.delete();
-            temp2.delete();
-        }
-    }
-
-    public static void sign(X509Certificate cert, PrivateKey key,
-                            JarMap input, OutputStream output) throws Exception {
-        sign(cert, key, input, output, false);
-    }
-
-    private static void sign(X509Certificate cert, PrivateKey key, JarMap input,
-                             OutputStream output, boolean wholeFile) throws Exception {
-        int hashes = 0;
-        hashes |= getDigestAlgorithm(cert);
-
-        // Set the ZIP file timestamp to the starting valid time
-        // of the 0th certificate plus one hour (to match what
-        // we've historically done).
-        long timestamp = cert.getNotBefore().getTime() + 3600L * 1000;
-
-        if (wholeFile) {
-            signWholeFile(input.getFile(), cert, key, output);
-        } else {
-            JarOutputStream outputJar = new JarOutputStream(output);
-            // 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);
-            Manifest manifest = addDigestsToManifest(input, hashes);
-            copyFiles(manifest, input, outputJar, timestamp, 4);
-            signFile(manifest, input, cert, key, outputJar);
-            outputJar.close();
-        }
-    }
+    /**
+     * Digest algorithm used when signing the APK using APK Signature Scheme v2.
+     */
+    private static final String APK_SIG_SCHEME_V2_DIGEST_ALGORITHM = "SHA-256";
+    // Files matching this pattern are not copied to the output.
+    private static final Pattern stripPattern =
+            Pattern.compile("^(META-INF/((.*)[.](SF|RSA|DSA|EC)|com/android/otacert))|(" +
+                    Pattern.quote(JarFile.MANIFEST_NAME) + ")$");
 
     /**
      * Return one of USE_SHA1 or USE_SHA256 according to the signature
@@ -122,7 +80,7 @@ public class SignAPK {
      */
     private static int getDigestAlgorithm(X509Certificate cert) {
         String sigAlg = cert.getSigAlgName().toUpperCase(Locale.US);
-        if (sigAlg.startsWith("SHA1WITHRSA") || sigAlg.startsWith("MD5WITHRSA")) {
+        if ("SHA1WITHRSA".equals(sigAlg) || "MD5WITHRSA".equals(sigAlg)) {
             return USE_SHA1;
         } else if (sigAlg.startsWith("SHA256WITH")) {
             return USE_SHA256;
@@ -132,9 +90,10 @@ public class SignAPK {
         }
     }
 
-    /** Returns the expected signature algorithm for this key type. */
+    /**
+     * Returns the expected signature algorithm for this key type.
+     */
     private static String getSignatureAlgorithm(X509Certificate cert) {
-        String sigAlg = cert.getSigAlgName().toUpperCase(Locale.US);
         String keyType = cert.getPublicKey().getAlgorithm().toUpperCase(Locale.US);
         if ("RSA".equalsIgnoreCase(keyType)) {
             if (getDigestAlgorithm(cert) == USE_SHA256) {
@@ -149,11 +108,6 @@ public class SignAPK {
         }
     }
 
-    // Files matching this pattern are not copied to the output.
-    private static Pattern stripPattern =
-            Pattern.compile("^(META-INF/((.*)[.](SF|RSA|DSA|EC)|com/android/otacert))|(" +
-                    Pattern.quote(JarFile.MANIFEST_NAME) + ")$");
-
     /**
      * Add the hash(es) of every file to the manifest, creating it if
      * necessary.
@@ -169,6 +123,7 @@ public class SignAPK {
             main.putValue("Manifest-Version", "1.0");
             main.putValue("Created-By", "1.0 (Android SignApk)");
         }
+
         MessageDigest md_sha1 = null;
         MessageDigest md_sha256 = null;
         if ((hashes & USE_SHA1) != 0) {
@@ -177,30 +132,51 @@ public class SignAPK {
         if ((hashes & USE_SHA256) != 0) {
             md_sha256 = MessageDigest.getInstance("SHA256");
         }
+
         byte[] buffer = new byte[4096];
         int num;
+
         // We sort the input entries by name, and add them to the
         // output manifest in sorted order.  We expect that the output
         // map will be deterministic.
+
         TreeMap<String, JarEntry> byName = new TreeMap<>();
+
         for (Enumeration<JarEntry> e = jar.entries(); e.hasMoreElements(); ) {
             JarEntry entry = e.nextElement();
             byName.put(entry.getName(), entry);
         }
-        for (JarEntry entry: byName.values()) {
+
+        for (JarEntry entry : byName.values()) {
             String name = entry.getName();
-            if (!entry.isDirectory() &&
-                    (stripPattern == null || !stripPattern.matcher(name).matches())) {
+            if (!entry.isDirectory() && !stripPattern.matcher(name).matches()) {
                 InputStream data = jar.getInputStream(entry);
                 while ((num = data.read(buffer)) > 0) {
                     if (md_sha1 != null) md_sha1.update(buffer, 0, num);
                     if (md_sha256 != null) md_sha256.update(buffer, 0, num);
                 }
-                Attributes attr = new Attributes();
+
+                Attributes attr = null;
+                if (input != null) attr = input.getAttributes(name);
+                attr = attr != null ? new Attributes(attr) : new Attributes();
+                // Remove any previously computed digests from this entry's attributes.
+                for (Iterator<Object> i = attr.keySet().iterator(); i.hasNext(); ) {
+                    Object key = i.next();
+                    if (!(key instanceof Attributes.Name)) {
+                        continue;
+                    }
+                    String attributeNameLowerCase =
+                            key.toString().toLowerCase(Locale.US);
+                    if (attributeNameLowerCase.endsWith("-digest")) {
+                        i.remove();
+                    }
+                }
+                // Add SHA-1 digest if requested
                 if (md_sha1 != null) {
                     attr.putValue("SHA1-Digest",
                             new String(Base64.encode(md_sha1.digest()), "ASCII"));
                 }
+                // Add SHA-256 digest if requested
                 if (md_sha256 != null) {
                     attr.putValue("SHA-256-Digest",
                             new String(Base64.encode(md_sha256.digest()), "ASCII"));
@@ -208,62 +184,39 @@ public class SignAPK {
                 output.getEntries().put(name, attr);
             }
         }
+
         return output;
     }
 
     /**
-     * Write to another stream and track how many bytes have been
-     * written.
+     * Write a .SF file with a digest of the specified manifest.
      */
-    private static class CountOutputStream extends FilterOutputStream {
-        private int mCount;
-        public CountOutputStream(OutputStream out) {
-            super(out);
-            mCount = 0;
-        }
-        @Override
-        public void write(int b) throws IOException {
-            super.write(b);
-            mCount++;
-        }
-        @Override
-        public void write(byte[] b, int off, int len) throws IOException {
-            super.write(b, off, len);
-            mCount += len;
-        }
-        public int size() {
-            return mCount;
-        }
-    }
-
-    /**
-     * An OutputStream that does literally nothing
-     */
-    private static OutputStream stubStream = new OutputStream() {
-        @Override
-        public void write(int b) {}
-
-        @Override
-        public void write(byte[] b, int off, int len) {}
-    };
-
-    /** Write a .SF file with a digest of the specified manifest. */
-    private static void writeSignatureFile(Manifest manifest, OutputStream out, int hash)
+    private static void writeSignatureFile(Manifest manifest, OutputStream out,
+                                           int hash)
             throws IOException, GeneralSecurityException {
         Manifest sf = new Manifest();
         Attributes main = sf.getMainAttributes();
         main.putValue("Signature-Version", "1.0");
         main.putValue("Created-By", "1.0 (Android SignApk)");
-        MessageDigest md = MessageDigest.getInstance(
-                hash == USE_SHA256 ? "SHA256" : "SHA1");
-        PrintStream print = new PrintStream(
-                new DigestOutputStream(stubStream, md),
+        // Add APK Signature Scheme v2 signature stripping protection.
+        // This attribute indicates that this APK is supposed to have been signed using one or
+        // more APK-specific signature schemes in addition to the standard JAR signature scheme
+        // used by this code. APK signature verifier should reject the APK if it does not
+        // contain a signature for the signature scheme the verifier prefers out of this set.
+        main.putValue(
+                ApkSignerV2.SF_ATTRIBUTE_ANDROID_APK_SIGNED_NAME,
+                ApkSignerV2.SF_ATTRIBUTE_ANDROID_APK_SIGNED_VALUE);
+
+        MessageDigest md = MessageDigest.getInstance(hash == USE_SHA256 ? "SHA256" : "SHA1");
+        PrintStream print = new PrintStream(new DigestOutputStream(new ByteArrayOutputStream(), md),
                 true, "UTF-8");
+
         // Digest of the entire manifest
         manifest.write(print);
         print.flush();
         main.putValue(hash == USE_SHA256 ? "SHA-256-Digest-Manifest" : "SHA1-Digest-Manifest",
                 new String(Base64.encode(md.digest()), "ASCII"));
+
         Map<String, Attributes> entries = manifest.getEntries();
         for (Map.Entry<String, Attributes> entry : entries.entrySet()) {
             // Digest of the manifest stanza for this entry.
@@ -273,13 +226,16 @@ public class SignAPK {
             }
             print.print("\r\n");
             print.flush();
+
             Attributes sfAttr = new Attributes();
             sfAttr.putValue(hash == USE_SHA256 ? "SHA-256-Digest" : "SHA1-Digest",
                     new String(Base64.encode(md.digest()), "ASCII"));
             sf.getEntries().put(entry.getKey(), sfAttr);
         }
+
         CountOutputStream cout = new CountOutputStream(out);
         sf.write(cout);
+
         // A bug in the java.util.jar implementation of Android platforms
         // up to version 1.6 will cause a spurious IOException to be thrown
         // if the length of the signature file is a multiple of 1024 bytes.
@@ -290,10 +246,11 @@ public class SignAPK {
         }
     }
 
-    /** Sign data and write the digital signature to 'out'. */
+    /**
+     * Sign data and write the digital signature to 'out'.
+     */
     private static void writeSignatureBlock(
-            CMSTypedData data, X509Certificate publicKey, PrivateKey privateKey,
-            OutputStream out)
+            CMSTypedData data, X509Certificate publicKey, PrivateKey privateKey, OutputStream out)
             throws IOException,
             CertificateEncodingException,
             OperatorCreationException,
@@ -301,19 +258,22 @@ public class SignAPK {
         ArrayList<X509Certificate> certList = new ArrayList<>(1);
         certList.add(publicKey);
         JcaCertStore certs = new JcaCertStore(certList);
+
         CMSSignedDataGenerator gen = new CMSSignedDataGenerator();
         ContentSigner signer = new JcaContentSignerBuilder(getSignatureAlgorithm(publicKey))
                 .build(privateKey);
         gen.addSignerInfoGenerator(
-                new JcaSignerInfoGeneratorBuilder(
-                        new JcaDigestCalculatorProviderBuilder().build())
+                new JcaSignerInfoGeneratorBuilder(new JcaDigestCalculatorProviderBuilder().build())
                         .setDirectSignature(true)
-                        .build(signer, publicKey));
+                        .build(signer, publicKey)
+        );
         gen.addCertificates(certs);
         CMSSignedData sigData = gen.generate(data, false);
-        ASN1InputStream asn1 = new ASN1InputStream(sigData.getEncoded());
-        ASN1OutputStream dos = ASN1OutputStream.create(out, ASN1Encoding.DER);
-        dos.writeObject(asn1.readObject());
+
+        try (ASN1InputStream asn1 = new ASN1InputStream(sigData.getEncoded())) {
+            ASN1OutputStream dos = ASN1OutputStream.create(out, ASN1Encoding.DER);
+            dos.writeObject(asn1.readObject());
+        }
     }
 
     /**
@@ -323,27 +283,37 @@ public class SignAPK {
      * more efficient.
      */
     private static void copyFiles(Manifest manifest, JarMap in, JarOutputStream out,
-                                  long timestamp, int alignment) throws IOException {
+                                  long timestamp, int defaultAlignment) throws IOException {
         byte[] buffer = new byte[4096];
         int num;
+
         Map<String, Attributes> entries = manifest.getEntries();
         ArrayList<String> names = new ArrayList<>(entries.keySet());
         Collections.sort(names);
+
         boolean firstEntry = true;
         long offset = 0L;
+
         // We do the copy in two passes -- first copying all the
         // entries that are STORED, then copying all the entries that
         // have any other compression flag (which in practice means
         // DEFLATED).  This groups all the stored entries together at
         // the start of the file and makes it easier to do alignment
         // on them (since only stored entries are aligned).
+
         for (String name : names) {
             JarEntry inEntry = in.getJarEntry(name);
-            JarEntry outEntry = null;
+            JarEntry outEntry;
             if (inEntry.getMethod() != JarEntry.STORED) continue;
             // Preserve the STORED method of the input entry.
             outEntry = new JarEntry(inEntry);
             outEntry.setTime(timestamp);
+            // Discard comment and extra fields of this entry to
+            // simplify alignment logic below and for consistency with
+            // how compressed entries are handled later.
+            outEntry.setComment(null);
+            outEntry.setExtra(null);
+
             // 'offset' is the offset into the file at which we expect
             // the file data to begin.  This is the value we need to
             // make a multiple of 'alignement'.
@@ -357,15 +327,18 @@ public class SignAPK {
                 offset += 4;
                 firstEntry = false;
             }
+            int alignment = getStoredEntryDataAlignment(name, defaultAlignment);
             if (alignment > 0 && (offset % alignment != 0)) {
                 // Set the "extra data" of the entry to between 1 and
                 // alignment-1 bytes, to make the file data begin at
                 // an aligned offset.
-                int needed = alignment - (int)(offset % alignment);
+                int needed = alignment - (int) (offset % alignment);
                 outEntry.setExtra(new byte[needed]);
                 offset += needed;
             }
+
             out.putNextEntry(outEntry);
+
             InputStream data = in.getInputStream(inEntry);
             while ((num = data.read(buffer)) > 0) {
                 out.write(buffer, 0, num);
@@ -373,17 +346,20 @@ public class SignAPK {
             }
             out.flush();
         }
+
         // Copy all the non-STORED entries.  We don't attempt to
         // maintain the 'offset' variable past this point; we don't do
         // alignment on these entries.
+
         for (String name : names) {
             JarEntry inEntry = in.getJarEntry(name);
-            JarEntry outEntry = null;
+            JarEntry outEntry;
             if (inEntry.getMethod() == JarEntry.STORED) continue;
             // 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);
@@ -392,135 +368,203 @@ public class SignAPK {
         }
     }
 
-    // This class is to provide a file's content, but trimming out the last two bytes
-    // Used for signWholeFile
-    private static class CMSProcessableFile implements CMSTypedData {
-
-        private ASN1ObjectIdentifier type;
-        private RandomAccessFile file;
-
-        CMSProcessableFile(File file) throws FileNotFoundException {
-            this.file = new RandomAccessFile(file, "r");
-            type = new ASN1ObjectIdentifier(CMSObjectIdentifiers.data.getId());
+    /**
+     * Returns the multiple (in bytes) at which the provided {@code STORED} entry's data must start
+     * relative to start of file or {@code 0} if alignment of this entry's data is not important.
+     */
+    private static int getStoredEntryDataAlignment(String entryName, int defaultAlignment) {
+        if (defaultAlignment <= 0) {
+            return 0;
         }
 
-        @Override
-        public ASN1ObjectIdentifier getContentType() {
-            return type;
-        }
-
-        @Override
-        public void write(OutputStream out) throws IOException, CMSException {
-            file.seek(0);
-            int read;
-            byte buffer[] = new byte[4096];
-            int len = (int) file.length() - 2;
-            while ((read = file.read(buffer, 0, len < buffer.length ? len : buffer.length)) > 0) {
-                out.write(buffer, 0, read);
-                len -= read;
-            }
-        }
-
-        @Override
-        public Object getContent() {
-            return file;
-        }
-
-        byte[] getTail() throws IOException {
-            byte tail[] = new byte[22];
-            file.seek(file.length() - 22);
-            file.readFully(tail);
-            return tail;
+        if (entryName.endsWith(".so")) {
+            // Align .so contents to memory page boundary to enable memory-mapped
+            // execution.
+            return 4096;
+        } else {
+            return defaultAlignment;
         }
     }
 
-    private static void signWholeFile(File input, X509Certificate publicKey,
-                                      PrivateKey privateKey, OutputStream outputStream)
-            throws Exception {
-        ByteArrayOutputStream temp = new ByteArrayOutputStream();
-        // put a readable message and a null char at the start of the
-        // archive comment, so that tools that display the comment
-        // (hopefully) show something sensible.
-        // TODO: anything more useful we can put in this message?
-        byte[] message = "signed by SignApk".getBytes("UTF-8");
-        temp.write(message);
-        temp.write(0);
-
-        CMSProcessableFile cmsFile = new CMSProcessableFile(input);
-        writeSignatureBlock(cmsFile, publicKey, privateKey, temp);
-
-        // 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.
-        byte[] zipData = cmsFile.getTail();
-        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");
-        }
-        // signature starts this many bytes from the end of the file
-        int signature_start = total_size - message.length - 1;
-        temp.write(signature_start & 0xff);
-        temp.write((signature_start >> 8) & 0xff);
-        // Why the 0xff bytes?  In a zip file with no archive comment,
-        // bytes [-6:-2] of the file are the little-endian offset from
-        // the start of the file to the central directory.  So for the
-        // two high bytes to be 0xff 0xff, the archive would have to
-        // be nearly 4GB in size.  So it's unlikely that a real
-        // commentless archive would have 0xffs here, and lets us tell
-        // an old signed archive from a new one.
-        temp.write(0xff);
-        temp.write(0xff);
-        temp.write(total_size & 0xff);
-        temp.write((total_size >> 8) & 0xff);
-        temp.flush();
-        // Signature verification checks that the EOCD header is the
-        // last such sequence in the file (to avoid minzip finding a
-        // fake EOCD appended after the signature in its scan).  The
-        // odds of producing this sequence by chance are very low, but
-        // let's catch it here if it does.
-        byte[] b = temp.toByteArray();
-        for (int i = 0; i < b.length-3; ++i) {
-            if (b[i] == 0x50 && b[i+1] == 0x4b && b[i+2] == 0x05 && b[i+3] == 0x06) {
-                throw new IllegalArgumentException("found spurious EOCD header at " + i);
-            }
-        }
-        cmsFile.write(outputStream);
-        outputStream.write(total_size & 0xff);
-        outputStream.write((total_size >> 8) & 0xff);
-        temp.writeTo(outputStream);
-        outputStream.close();
-    }
-
-    private static void signFile(Manifest manifest, JarMap inputJar,
-                                 X509Certificate cert, PrivateKey privateKey,
-                                 JarOutputStream outputJar)
-            throws Exception {
-        // Assume the certificate is valid for at least an hour.
-        long timestamp = cert.getNotBefore().getTime() + 3600L * 1000;
+    private static void signFile(Manifest manifest,
+                                 X509Certificate[] publicKey, PrivateKey[] privateKey,
+                                 long timestamp, JarOutputStream outputJar) throws Exception {
         // MANIFEST.MF
         JarEntry je = new JarEntry(JarFile.MANIFEST_NAME);
         je.setTime(timestamp);
         outputJar.putNextEntry(je);
         manifest.write(outputJar);
-        je = new JarEntry(CERT_SF_NAME);
-        je.setTime(timestamp);
-        outputJar.putNextEntry(je);
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        writeSignatureFile(manifest, baos, getDigestAlgorithm(cert));
-        byte[] signedData = baos.toByteArray();
-        outputJar.write(signedData);
-        // CERT.{EC,RSA} / CERT#.{EC,RSA}
-        final String keyType = cert.getPublicKey().getAlgorithm();
-        je = new JarEntry(String.format(CERT_SIG_NAME, keyType));
-        je.setTime(timestamp);
-        outputJar.putNextEntry(je);
-        writeSignatureBlock(new CMSProcessableByteArray(signedData),
-                cert, privateKey, 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(Locale.US, CERT_SF_MULTI_NAME, k)));
+            je.setTime(timestamp);
+            outputJar.putNextEntry(je);
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            writeSignatureFile(manifest, baos, getDigestAlgorithm(publicKey[k]));
+            byte[] signedData = baos.toByteArray();
+            outputJar.write(signedData);
+
+            // CERT.{EC,RSA} / CERT#.{EC,RSA}
+            final String keyType = publicKey[k].getPublicKey().getAlgorithm();
+            je = new JarEntry(numKeys == 1 ? (String.format(CERT_SIG_NAME, keyType)) :
+                    (String.format(Locale.US, CERT_SIG_MULTI_NAME, k, keyType)));
+            je.setTime(timestamp);
+            outputJar.putNextEntry(je);
+            writeSignatureBlock(new CMSProcessableByteArray(signedData),
+                    publicKey[k], privateKey[k], outputJar);
+        }
+    }
+
+    /**
+     * Converts the provided lists of private keys, their X.509 certificates, and digest algorithms
+     * into a list of APK Signature Scheme v2 {@code SignerConfig} instances.
+     */
+    private static List<ApkSignerV2.SignerConfig> createV2SignerConfigs(
+            PrivateKey[] privateKeys, X509Certificate[] certificates, String[] digestAlgorithms)
+            throws InvalidKeyException {
+        if (privateKeys.length != certificates.length) {
+            throw new IllegalArgumentException(
+                    "The number of private keys must match the number of certificates: "
+                            + privateKeys.length + " vs" + certificates.length);
+        }
+        List<ApkSignerV2.SignerConfig> result = new ArrayList<>(privateKeys.length);
+        for (int i = 0; i < privateKeys.length; i++) {
+            PrivateKey privateKey = privateKeys[i];
+            X509Certificate certificate = certificates[i];
+            PublicKey publicKey = certificate.getPublicKey();
+            String keyAlgorithm = privateKey.getAlgorithm();
+            if (!keyAlgorithm.equalsIgnoreCase(publicKey.getAlgorithm())) {
+                throw new InvalidKeyException(
+                        "Key algorithm of private key #" + (i + 1) + " does not match key"
+                                + " algorithm of public key #" + (i + 1) + ": " + keyAlgorithm
+                                + " vs " + publicKey.getAlgorithm());
+            }
+            ApkSignerV2.SignerConfig signerConfig = new ApkSignerV2.SignerConfig();
+            signerConfig.privateKey = privateKey;
+            signerConfig.certificates = Collections.singletonList(certificate);
+            List<Integer> signatureAlgorithms = new ArrayList<>(digestAlgorithms.length);
+            for (String digestAlgorithm : digestAlgorithms) {
+                try {
+                    signatureAlgorithms.add(getV2SignatureAlgorithm(keyAlgorithm, digestAlgorithm));
+                } catch (IllegalArgumentException e) {
+                    throw new InvalidKeyException(
+                            "Unsupported key and digest algorithm combination for signer #"
+                                    + (i + 1), e);
+                }
+            }
+            signerConfig.signatureAlgorithms = signatureAlgorithms;
+            result.add(signerConfig);
+        }
+        return result;
+    }
+
+    private static int getV2SignatureAlgorithm(String keyAlgorithm, String digestAlgorithm) {
+        if ("SHA-256".equalsIgnoreCase(digestAlgorithm)) {
+            if ("RSA".equalsIgnoreCase(keyAlgorithm)) {
+                // Use RSASSA-PKCS1-v1_5 signature scheme instead of RSASSA-PSS to guarantee
+                // deterministic signatures which make life easier for OTA updates (fewer files
+                // changed when deterministic signature schemes are used).
+                return ApkSignerV2.SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA256;
+            } else if ("EC".equalsIgnoreCase(keyAlgorithm)) {
+                return ApkSignerV2.SIGNATURE_ECDSA_WITH_SHA256;
+            } else if ("DSA".equalsIgnoreCase(keyAlgorithm)) {
+                return ApkSignerV2.SIGNATURE_DSA_WITH_SHA256;
+            } else {
+                throw new IllegalArgumentException("Unsupported key algorithm: " + keyAlgorithm);
+            }
+        } else if ("SHA-512".equalsIgnoreCase(digestAlgorithm)) {
+            if ("RSA".equalsIgnoreCase(keyAlgorithm)) {
+                // Use RSASSA-PKCS1-v1_5 signature scheme instead of RSASSA-PSS to guarantee
+                // deterministic signatures which make life easier for OTA updates (fewer files
+                // changed when deterministic signature schemes are used).
+                return ApkSignerV2.SIGNATURE_RSA_PKCS1_V1_5_WITH_SHA512;
+            } else if ("EC".equalsIgnoreCase(keyAlgorithm)) {
+                return ApkSignerV2.SIGNATURE_ECDSA_WITH_SHA512;
+            } else if ("DSA".equalsIgnoreCase(keyAlgorithm)) {
+                return ApkSignerV2.SIGNATURE_DSA_WITH_SHA512;
+            } else {
+                throw new IllegalArgumentException("Unsupported key algorithm: " + keyAlgorithm);
+            }
+        } else {
+            throw new IllegalArgumentException("Unsupported digest algorithm: " + digestAlgorithm);
+        }
+    }
+
+    public static void sign(X509Certificate cert, PrivateKey key,
+                            JarMap inputJar, FileOutputStream outputFile) throws Exception {
+        int alignment = 4;
+        int hashes = 0;
+
+        X509Certificate[] publicKey = new X509Certificate[1];
+        publicKey[0] = cert;
+        hashes |= getDigestAlgorithm(publicKey[0]);
+
+        // Set all ZIP file timestamps to Jan 1 2009 00:00:00.
+        long timestamp = 1230768000000L;
+        // The Java ZipEntry API we're using converts milliseconds since epoch into MS-DOS
+        // timestamp using the current timezone. We thus adjust the milliseconds since epoch
+        // value to end up with MS-DOS timestamp of Jan 1 2009 00:00:00.
+        timestamp -= TimeZone.getDefault().getOffset(timestamp);
+
+        PrivateKey[] privateKey = new PrivateKey[1];
+        privateKey[0] = key;
+
+        // Generate, in memory, an APK signed using standard JAR Signature Scheme.
+        ByteArrayOutputStream v1SignedApkBuf = new ByteArrayOutputStream();
+        JarOutputStream outputJar = new JarOutputStream(v1SignedApkBuf);
+        // Use maximum compression for compressed entries because the APK lives forever on
+        // the system partition.
+        outputJar.setLevel(9);
+        Manifest manifest = addDigestsToManifest(inputJar, hashes);
+        copyFiles(manifest, inputJar, outputJar, timestamp, alignment);
+        signFile(manifest, publicKey, privateKey, timestamp, outputJar);
+        outputJar.close();
+        ByteBuffer v1SignedApk = ByteBuffer.wrap(v1SignedApkBuf.toByteArray());
+        v1SignedApkBuf.reset();
+
+        ByteBuffer[] outputChunks;
+        List<ApkSignerV2.SignerConfig> signerConfigs = createV2SignerConfigs(privateKey, publicKey,
+                new String[]{APK_SIG_SCHEME_V2_DIGEST_ALGORITHM});
+        outputChunks = ApkSignerV2.sign(v1SignedApk, signerConfigs);
+
+        // This assumes outputChunks are array-backed. To avoid this assumption, the
+        // code could be rewritten to use FileChannel.
+        for (ByteBuffer outputChunk : outputChunks) {
+            outputFile.write(outputChunk.array(),
+                    outputChunk.arrayOffset() + outputChunk.position(), outputChunk.remaining());
+            outputChunk.position(outputChunk.limit());
+        }
+    }
+
+    /**
+     * Write to another stream and track how many bytes have been
+     * written.
+     */
+    private static class CountOutputStream extends FilterOutputStream {
+        private int mCount;
+
+        public CountOutputStream(OutputStream out) {
+            super(out);
+            mCount = 0;
+        }
+
+        @Override
+        public void write(int b) throws IOException {
+            super.write(b);
+            mCount++;
+        }
+
+        @Override
+        public void write(byte[] b, int off, int len) throws IOException {
+            super.write(b, off, len);
+            mCount += len;
+        }
+
+        public int size() {
+            return mCount;
+        }
     }
 }

app/signing/src/main/java/com/topjohnwu/signing/ZipAdjust.java

@@ -1,277 +0,0 @@
-package com.topjohnwu.signing;
-
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.io.RandomAccessFile;
-import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
-
-public class ZipAdjust {
-
-    public static void adjust(File input, File output) throws IOException {
-        try (
-            RandomAccessFile in = new RandomAccessFile(input, "r");
-            FileOutputStream out = new FileOutputStream(output)
-        ) {
-            adjust(in, out);
-        }
-    }
-
-    public static void adjust(RandomAccessFile in, OutputStream out) throws IOException {
-
-        CentralFooter footer = new CentralFooter(in);
-        int outOff = 0;
-        long centralOff = unsigned(footer.centralDirectoryOffset);
-        CentralHeader[] centralHeaders = new CentralHeader[unsigned(footer.numEntries)];
-
-        // Loop through central directory entries
-        for (int i = 0; i < centralHeaders.length; ++i) {
-            // Read central header
-            in.seek(centralOff);
-            centralHeaders[i] = new CentralHeader(in);
-            centralOff = in.getFilePointer();
-
-            // Read local header
-            in.seek(unsigned(centralHeaders[i].localHeaderOffset));
-            LocalHeader localHeader = new LocalHeader(in);
-
-            // Make sure local and central headers matches, and strip out data descriptor flag
-            centralHeaders[i].localHeaderOffset = outOff;
-            centralHeaders[i].flags &= ~(1 << 3);
-            localHeader.flags = centralHeaders[i].flags;
-            localHeader.crc32 = centralHeaders[i].crc32;
-            localHeader.compressedSize = centralHeaders[i].compressedSize;
-            localHeader.uncompressedSize = centralHeaders[i].uncompressedSize;
-            localHeader.fileNameLength = centralHeaders[i].fileNameLength;
-            localHeader.filename = centralHeaders[i].filename;
-
-            // Write local header
-            outOff += localHeader.write(out);
-
-            // Copy data
-            int read;
-            long len = unsigned(localHeader.compressedSize);
-            outOff += len;
-            byte data[] = new byte[4096];
-            while ((read = in.read(data, 0,
-                    len < data.length ? (int) len : data.length)) > 0) {
-                out.write(data, 0, read);
-                len -= read;
-            }
-        }
-
-        footer.centralDirectoryOffset = outOff;
-
-        // Write central directory
-        outOff = 0;
-        for (CentralHeader header : centralHeaders)
-            outOff += header.write(out);
-
-        // Write central directory record
-        footer.centralDirectorySize = outOff;
-        footer.write(out);
-    }
-
-    public static short unsigned(byte n) {
-        return (short)(n & 0xff);
-    }
-
-    public static int unsigned(short n) {
-        return n & 0xffff;
-    }
-
-    public static long unsigned(int n) {
-        return n & 0xffffffffL;
-    }
-
-    public static class CentralFooter {
-
-        static final int MAGIC =  0x06054b50;
-        
-        int signature;
-        short diskNumber;
-        short centralDirectoryDiskNumber;
-        short numEntriesThisDisk;
-        short numEntries;
-        int centralDirectorySize;
-        int centralDirectoryOffset;
-        short zipCommentLength;
-        // byte[] comments;
-
-        CentralFooter(RandomAccessFile file) throws IOException {
-            byte[] buffer = new byte[22];
-            for (long i = file.length() - 4; i >= 0; --i) {
-                file.seek(i);
-                file.read(buffer, 0 ,4);
-                ByteBuffer buf = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN);
-                signature = buf.getInt();
-                if (signature != MAGIC) {
-                    continue;
-                }
-                file.read(buffer, 4, buffer.length - 4);
-                diskNumber = buf.getShort();
-                centralDirectoryDiskNumber = buf.getShort();
-                numEntriesThisDisk = buf.getShort();
-                numEntries = buf.getShort();
-                centralDirectorySize = buf.getInt();
-                centralDirectoryOffset = buf.getInt();
-                zipCommentLength = buf.getShort();
-                break;
-            }
-        }
-
-        int write(OutputStream out) throws IOException {
-            byte[] buffer = new byte[22];
-            ByteBuffer buf = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN);
-            buf.putInt(signature);
-            buf.putShort(diskNumber);
-            buf.putShort(centralDirectoryDiskNumber);
-            buf.putShort(numEntriesThisDisk);
-            buf.putShort(numEntries);
-            buf.putInt(centralDirectorySize);
-            buf.putInt(centralDirectoryOffset);
-            buf.putShort((short) 0);  // zipCommentLength
-            out.write(buffer);
-            return buffer.length;
-        }
-    }
-
-    static class CentralHeader {
-
-        static final int MAGIC =  0x02014b50;
-
-        int signature;
-        short versionMadeBy;
-        short versionNeededToExtract;
-        short flags;
-        short compressionMethod;
-        short lastModFileTime;
-        short lastModFileDate;
-        int crc32;
-        int compressedSize;
-        int uncompressedSize;
-        short fileNameLength;
-        short extraFieldLength;
-        short fileCommentLength;
-        short diskNumberStart;
-        short internalFileAttributes;
-        int externalFileAttributes;
-        int localHeaderOffset;
-        byte[] filename;
-        // byte[] extra;
-        // byte[] comment;
-
-        CentralHeader(RandomAccessFile file) throws IOException {
-            byte[] buffer = new byte[46];
-            file.read(buffer);
-            ByteBuffer buf = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN);
-            signature = buf.getInt();
-            if (signature != MAGIC)
-                throw new IOException();
-            versionMadeBy = buf.getShort();
-            versionNeededToExtract = buf.getShort();
-            flags = buf.getShort();
-            compressionMethod = buf.getShort();
-            lastModFileTime = buf.getShort();
-            lastModFileDate = buf.getShort();
-            crc32 = buf.getInt();
-            compressedSize = buf.getInt();
-            uncompressedSize = buf.getInt();
-            fileNameLength = buf.getShort();
-            extraFieldLength = buf.getShort();
-            fileCommentLength = buf.getShort();
-            diskNumberStart = buf.getShort();
-            internalFileAttributes = buf.getShort();
-            externalFileAttributes = buf.getInt();
-            localHeaderOffset = buf.getInt();
-            filename = new byte[unsigned(fileNameLength)];
-            file.read(filename);
-            file.skipBytes(unsigned(extraFieldLength) + unsigned(fileCommentLength));
-        }
-
-        int write(OutputStream out) throws IOException {
-            byte[] buffer = new byte[46];
-            ByteBuffer buf = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN);
-            buf.putInt(signature);
-            buf.putShort(versionMadeBy);
-            buf.putShort(versionNeededToExtract);
-            buf.putShort(flags);
-            buf.putShort(compressionMethod);
-            buf.putShort(lastModFileTime);
-            buf.putShort(lastModFileDate);
-            buf.putInt(crc32);
-            buf.putInt(compressedSize);
-            buf.putInt(uncompressedSize);
-            buf.putShort(fileNameLength);
-            buf.putShort((short) 0); // extraFieldLength
-            buf.putShort((short) 0); // fileCommentLength
-            buf.putShort(diskNumberStart);
-            buf.putShort(internalFileAttributes);
-            buf.putInt(externalFileAttributes);
-            buf.putInt(localHeaderOffset);
-            out.write(buffer);
-            out.write(filename);
-            return buffer.length + filename.length;
-        }
-    }
-
-    static class LocalHeader {
-
-        static final int MAGIC = 0x04034b50;
-
-        int signature;
-        short versionNeededToExtract;
-        short flags;
-        short compressionMethod;
-        short lastModFileTime;
-        short lastModFileDate;
-        int crc32;
-        int compressedSize;
-        int uncompressedSize;
-        short fileNameLength;
-        short extraFieldLength;
-        byte[] filename;
-        // byte[] extra;
-
-        LocalHeader(RandomAccessFile file) throws IOException {
-            byte[] buffer = new byte[30];
-            file.read(buffer);
-            ByteBuffer buf = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN);
-            signature = buf.getInt();
-            if (signature != MAGIC)
-                throw new IOException();
-            versionNeededToExtract = buf.getShort();
-            flags = buf.getShort();
-            compressionMethod = buf.getShort();
-            lastModFileTime = buf.getShort();
-            lastModFileDate = buf.getShort();
-            crc32 = buf.getInt();
-            compressedSize = buf.getInt();
-            uncompressedSize = buf.getInt();
-            fileNameLength = buf.getShort();
-            extraFieldLength = buf.getShort();
-            file.skipBytes(unsigned(fileNameLength) + unsigned(extraFieldLength));
-        }
-
-        int write(OutputStream out) throws IOException {
-            byte[] buffer = new byte[30];
-            ByteBuffer buf = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN);
-            buf.putInt(signature);
-            buf.putShort(versionNeededToExtract);
-            buf.putShort(flags);
-            buf.putShort(compressionMethod);
-            buf.putShort(lastModFileTime);
-            buf.putShort(lastModFileDate);
-            buf.putInt(crc32);
-            buf.putInt(compressedSize);
-            buf.putInt(uncompressedSize);
-            buf.putShort(fileNameLength);
-            buf.putShort((short) 0); // extraFieldLength
-            out.write(buffer);
-            out.write(filename);
-            return buffer.length + filename.length;
-        }
-    }
-}

app/signing/src/main/java/com/topjohnwu/signing/ZipSigner.java

@@ -6,7 +6,6 @@ import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.io.OutputStream;
 import java.security.KeyStore;
 import java.security.KeyStoreException;
 import java.security.NoSuchAlgorithmException;
@@ -28,20 +27,20 @@ public class ZipSigner {
         System.exit(2);
     }
 
-    private static void sign(JarMap input, OutputStream output) throws Exception {
-        sign(SignAPK.class.getResourceAsStream("/keys/testkey.x509.pem"),
-                SignAPK.class.getResourceAsStream("/keys/testkey.pk8"), input, output);
+    private static void sign(JarMap input, FileOutputStream output) throws Exception {
+        sign(SignApk.class.getResourceAsStream("/keys/testkey.x509.pem"),
+                SignApk.class.getResourceAsStream("/keys/testkey.pk8"), input, output);
     }
 
     private static void sign(InputStream certIs, InputStream keyIs,
-                             JarMap input, OutputStream output) throws Exception {
+                             JarMap input, FileOutputStream output) throws Exception {
         X509Certificate cert = CryptoUtils.readCertificate(certIs);
         PrivateKey key = CryptoUtils.readPrivateKey(keyIs);
-        SignAPK.signAndAdjust(cert, key, input, output);
+        SignApk.sign(cert, key, input, output);
     }
 
     private static void sign(String keyStore, String keyStorePass, String alias, String keyPass,
-                             JarMap in, OutputStream out) throws Exception {
+                             JarMap in, FileOutputStream out) throws Exception {
         KeyStore ks;
         try {
             ks = KeyStore.getInstance("JKS");
@@ -56,7 +55,7 @@ public class ZipSigner {
         }
         X509Certificate cert = (X509Certificate) ks.getCertificate(alias);
         PrivateKey key = (PrivateKey) ks.getKey(alias, keyPass.toCharArray());
-        SignAPK.signAndAdjust(cert, key, in, out);
+        SignApk.sign(cert, key, in, out);
     }
 
     public static void main(String[] args) throws Exception {
@@ -66,7 +65,7 @@ public class ZipSigner {
         Security.insertProviderAt(new BouncyCastleProvider(), 1);
 
         try (JarMap in = JarMap.open(args[args.length - 2], false);
-             OutputStream out = new FileOutputStream(args[args.length - 1])) {
+             FileOutputStream out = new FileOutputStream(args[args.length - 1])) {
             if (args.length == 2) {
                 sign(in, out);
             } else if (args.length == 4) {

app/signing/src/main/java/com/topjohnwu/signing/ZipUtils.java

@@ -0,0 +1,136 @@
+package com.topjohnwu.signing;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+/**
+ * Assorted ZIP format helpers.
+ *
+ * <p>NOTE: Most helper methods operating on {@code ByteBuffer} instances expect that the byte
+ * order of these buffers is little-endian.
+ */
+public abstract class ZipUtils {
+
+    private static final int ZIP_EOCD_REC_MIN_SIZE = 22;
+    private static final int ZIP_EOCD_REC_SIG = 0x06054b50;
+    private static final int ZIP_EOCD_CENTRAL_DIR_SIZE_FIELD_OFFSET = 12;
+    private static final int ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_OFFSET = 16;
+    private static final int ZIP_EOCD_COMMENT_LENGTH_FIELD_OFFSET = 20;
+
+    private static final int ZIP64_EOCD_LOCATOR_SIZE = 20;
+    private static final int ZIP64_EOCD_LOCATOR_SIG = 0x07064b50;
+
+    private static final int UINT16_MAX_VALUE = 0xffff;
+
+    private ZipUtils() {
+    }
+
+    /**
+     * Returns the position at which ZIP End of Central Directory record starts in the provided
+     * buffer or {@code -1} if the record is not present.
+     *
+     * <p>NOTE: Byte order of {@code zipContents} must be little-endian.
+     */
+    public static int findZipEndOfCentralDirectoryRecord(ByteBuffer zipContents) {
+        assertByteOrderLittleEndian(zipContents);
+
+        // ZIP End of Central Directory (EOCD) record is located at the very end of the ZIP archive.
+        // The record can be identified by its 4-byte signature/magic which is located at the very
+        // beginning of the record. A complication is that the record is variable-length because of
+        // the comment field.
+        // The algorithm for locating the ZIP EOCD record is as follows. We search backwards from
+        // end of the buffer for the EOCD record signature. Whenever we find a signature, we check
+        // the candidate record's comment length is such that the remainder of the record takes up
+        // exactly the remaining bytes in the buffer. The search is bounded because the maximum
+        // size of the comment field is 65535 bytes because the field is an unsigned 16-bit number.
+
+        int archiveSize = zipContents.capacity();
+        if (archiveSize < ZIP_EOCD_REC_MIN_SIZE) {
+            return -1;
+        }
+        int maxCommentLength = Math.min(archiveSize - ZIP_EOCD_REC_MIN_SIZE, UINT16_MAX_VALUE);
+        int eocdWithEmptyCommentStartPosition = archiveSize - ZIP_EOCD_REC_MIN_SIZE;
+        for (int expectedCommentLength = 0; expectedCommentLength < maxCommentLength; expectedCommentLength++) {
+            int eocdStartPos = eocdWithEmptyCommentStartPosition - expectedCommentLength;
+            if (zipContents.getInt(eocdStartPos) == ZIP_EOCD_REC_SIG) {
+                int actualCommentLength = getUnsignedInt16(zipContents, eocdStartPos + ZIP_EOCD_COMMENT_LENGTH_FIELD_OFFSET);
+                if (actualCommentLength == expectedCommentLength) {
+                    return eocdStartPos;
+                }
+            }
+        }
+
+        return -1;
+    }
+
+    /**
+     * Returns {@code true} if the provided buffer contains a ZIP64 End of Central Directory
+     * Locator.
+     *
+     * <p>NOTE: Byte order of {@code zipContents} must be little-endian.
+     */
+    public static boolean isZip64EndOfCentralDirectoryLocatorPresent(ByteBuffer zipContents, int zipEndOfCentralDirectoryPosition) {
+        assertByteOrderLittleEndian(zipContents);
+
+        // ZIP64 End of Central Directory Locator immediately precedes the ZIP End of Central
+        // Directory Record.
+
+        int locatorPosition = zipEndOfCentralDirectoryPosition - ZIP64_EOCD_LOCATOR_SIZE;
+        if (locatorPosition < 0) {
+            return false;
+        }
+
+        return zipContents.getInt(locatorPosition) == ZIP64_EOCD_LOCATOR_SIG;
+    }
+
+    /**
+     * Returns the offset of the start of the ZIP Central Directory in the archive.
+     *
+     * <p>NOTE: Byte order of {@code zipEndOfCentralDirectory} must be little-endian.
+     */
+    public static long getZipEocdCentralDirectoryOffset(ByteBuffer zipEndOfCentralDirectory) {
+        assertByteOrderLittleEndian(zipEndOfCentralDirectory);
+        return getUnsignedInt32(zipEndOfCentralDirectory, zipEndOfCentralDirectory.position() + ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_OFFSET);
+    }
+
+    /**
+     * Sets the offset of the start of the ZIP Central Directory in the archive.
+     *
+     * <p>NOTE: Byte order of {@code zipEndOfCentralDirectory} must be little-endian.
+     */
+    public static void setZipEocdCentralDirectoryOffset(ByteBuffer zipEndOfCentralDirectory, long offset) {
+        assertByteOrderLittleEndian(zipEndOfCentralDirectory);
+        setUnsignedInt32(zipEndOfCentralDirectory, zipEndOfCentralDirectory.position() + ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_OFFSET, offset);
+    }
+
+    /**
+     * Returns the size (in bytes) of the ZIP Central Directory.
+     *
+     * <p>NOTE: Byte order of {@code zipEndOfCentralDirectory} must be little-endian.
+     */
+    public static long getZipEocdCentralDirectorySizeBytes(ByteBuffer zipEndOfCentralDirectory) {
+        assertByteOrderLittleEndian(zipEndOfCentralDirectory);
+        return getUnsignedInt32(zipEndOfCentralDirectory, zipEndOfCentralDirectory.position() + ZIP_EOCD_CENTRAL_DIR_SIZE_FIELD_OFFSET);
+    }
+
+    private static void assertByteOrderLittleEndian(ByteBuffer buffer) {
+        if (buffer.order() != ByteOrder.LITTLE_ENDIAN) {
+            throw new IllegalArgumentException("ByteBuffer byte order must be little endian");
+        }
+    }
+
+    private static int getUnsignedInt16(ByteBuffer buffer, int offset) {
+        return buffer.getShort(offset) & 0xffff;
+    }
+
+    private static long getUnsignedInt32(ByteBuffer buffer, int offset) {
+        return buffer.getInt(offset) & 0xffffffffL;
+    }
+
+    private static void setUnsignedInt32(ByteBuffer buffer, int offset, long value) {
+        if ((value < 0) || (value > 0xffffffffL)) {
+            throw new IllegalArgumentException("uint32 value of out range: " + value);
+        }
+        buffer.putInt(buffer.position() + offset, (int) value);
+    }
+}

app/src/main/java/com/topjohnwu/magisk/core/utils/Keygen.kt

@@ -39,7 +39,7 @@ class Keygen(context: Context) : CertKeyProvider {
     }
 
     private val start = Calendar.getInstance().apply { add(Calendar.MONTH, -3) }
-    private val end = Calendar.getInstance().apply { add(Calendar.YEAR, 30) }
+    private val end = start.apply { add(Calendar.YEAR, 30) }
 
     override val cert get() = provider.cert
     override val key get() = provider.key

app/src/main/java/com/topjohnwu/magisk/core/utils/PatchAPK.kt

@@ -13,7 +13,7 @@ import com.topjohnwu.magisk.data.network.GithubRawServices
 import com.topjohnwu.magisk.ktx.get
 import com.topjohnwu.magisk.ktx.writeTo
 import com.topjohnwu.signing.JarMap
-import com.topjohnwu.signing.SignAPK
+import com.topjohnwu.signing.SignApk
 import com.topjohnwu.superuser.Shell
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.GlobalScope
@@ -29,10 +29,8 @@ import java.security.SecureRandom
 
 object PatchAPK {
 
-    private const val ALPHA = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-    private const val DIGITS = "0123456789"
-    const val ALPHANUM = ALPHA + DIGITS
-    private const val ALPHANUMDOTS = "$ALPHANUM............"
+    private const val ALPHA = "abcdefghijklmnopqrstuvwxyz"
+    private const val ALPHADOTS = "$ALPHA....."
 
     private const val APP_ID = "com.topjohnwu.magisk"
     private const val APP_NAME = "Magisk Manager"
@@ -48,7 +46,7 @@ object PatchAPK {
             next = if (prev == '.' || i == len - 1) {
                 ALPHA[random.nextInt(ALPHA.length)]
             } else {
-                ALPHANUMDOTS[random.nextInt(ALPHANUMDOTS.length)]
+                ALPHADOTS[random.nextInt(ALPHADOTS.length)]
             }
             builder.append(next)
             prev = next
@@ -96,7 +94,7 @@ object PatchAPK {
             // Write apk changes
             jar.getOutputStream(je).write(xml)
             val keys = Keygen(get())
-            SignAPK.sign(keys.cert, keys.key, jar, FileOutputStream(out).buffered())
+            SignApk.sign(keys.cert, keys.key, jar, FileOutputStream(out))
         } catch (e: Exception) {
             Timber.e(e)
             return false