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

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Java
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package com.topjohnwu.signing;
import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1OutputStream;
import org.bouncycastle.cert.jcajce.JcaCertStore;
import org.bouncycastle.cms.CMSException;
import org.bouncycastle.cms.CMSProcessableByteArray;
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.ByteArrayOutputStream;
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.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;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;
import java.util.regex.Pattern;
/*
* 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;
/**
* 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
* algorithm specified in the cert.
*/
private static int getDigestAlgorithm(X509Certificate cert) {
String sigAlg = cert.getSigAlgName().toUpperCase(Locale.US);
if ("SHA1WITHRSA".equals(sigAlg) || "MD5WITHRSA".equals(sigAlg)) {
return USE_SHA1;
} else if (sigAlg.startsWith("SHA256WITH")) {
return USE_SHA256;
} else {
throw new IllegalArgumentException("unsupported signature algorithm \"" + sigAlg +
"\" in cert [" + cert.getSubjectDN());
}
}
/**
* Returns the expected signature algorithm for this key type.
*/
private static String getSignatureAlgorithm(X509Certificate cert) {
String keyType = cert.getPublicKey().getAlgorithm().toUpperCase(Locale.US);
if ("RSA".equalsIgnoreCase(keyType)) {
if (getDigestAlgorithm(cert) == USE_SHA256) {
return "SHA256withRSA";
} else {
return "SHA1withRSA";
}
} else if ("EC".equalsIgnoreCase(keyType)) {
return "SHA256withECDSA";
} else {
throw new IllegalArgumentException("unsupported key type: " + keyType);
}
}
/**
* Add the hash(es) of every file to the manifest, creating it if
* necessary.
*/
private static Manifest addDigestsToManifest(JarMap jar, int hashes)
throws IOException, GeneralSecurityException {
Manifest input = jar.getManifest();
Manifest output = new Manifest();
Attributes main = output.getMainAttributes();
if (input != null) {
main.putAll(input.getMainAttributes());
} else {
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) {
md_sha1 = MessageDigest.getInstance("SHA1");
}
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()) {
String name = entry.getName();
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 = 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"));
}
output.getEntries().put(name, attr);
}
}
return output;
}
/**
* Write a .SF file with a digest of the specified manifest.
*/
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)");
// 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.
print.print("Name: " + entry.getKey() + "\r\n");
for (Map.Entry<Object, Object> att : entry.getValue().entrySet()) {
print.print(att.getKey() + ": " + att.getValue() + "\r\n");
}
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.
// As a workaround, add an extra CRLF in this case.
if ((cout.size() % 1024) == 0) {
cout.write('\r');
cout.write('\n');
}
}
/**
* Sign data and write the digital signature to 'out'.
*/
private static void writeSignatureBlock(
CMSTypedData data, X509Certificate publicKey, PrivateKey privateKey, OutputStream out)
throws IOException,
CertificateEncodingException,
OperatorCreationException,
CMSException {
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())
.setDirectSignature(true)
.build(signer, publicKey)
);
gen.addCertificates(certs);
CMSSignedData sigData = gen.generate(data, false);
try (ASN1InputStream asn1 = new ASN1InputStream(sigData.getEncoded())) {
ASN1OutputStream dos = ASN1OutputStream.create(out, ASN1Encoding.DER);
dos.writeObject(asn1.readObject());
}
}
/**
* Copy all the files in a manifest from input to output. We set
* the modification times in the output to a fixed time, so as to
* reduce variation in the output file and make incremental OTAs
* more efficient.
*/
private static void copyFiles(Manifest manifest, JarMap in, JarOutputStream out,
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;
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'.
offset += JarFile.LOCHDR + outEntry.getName().length();
if (firstEntry) {
// The first entry in a jar file has an extra field of
// four bytes that you can't get rid of; any extra
// data you specify in the JarEntry is appended to
// these forced four bytes. This is JAR_MAGIC in
// JarOutputStream; the bytes are 0xfeca0000.
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);
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);
offset += num;
}
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;
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);
}
out.flush();
}
}
/**
* 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;
}
if (entryName.endsWith(".so")) {
// Align .so contents to memory page boundary to enable memory-mapped
// execution.
return 4096;
} else {
return defaultAlignment;
}
}
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);
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;
}
}
}
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