From c2c49ed0c13846f7f96249c7419971dfcddc9215 Mon Sep 17 00:00:00 2001 From: Alex Klyubin Date: Mon, 11 Jan 2016 13:22:22 -0800 Subject: [PATCH] Unconditionally use SHA-256 when minSdkVersion is 18 or higher. SHA-1 is deprecated, but the replacement SHA-256 is only supported for JAR/APK and OTA update package signatures on API Level 18 and newer. This change thus adds a --min-sdk-version command-line parameter to signapk. When this parameter is set to 18 or higher, SHA-256 is used instead of SHA-1. When the parameter is not provided, SHA-1 is used same as before. This change also removes any other digests from the MANIFEST.MF. This is to ignore any MANIFEST.MF digests already there in the APK, such as when re-signing an already signed APK. Build scripts will be modified to provide the --min-sdk-version parameter in a follow-up change. This is not done in this change because of prebuilts which require a prebuilt version of signapk to support this parameter before the build scripts can be modified. Bug: 25643280 Change-Id: I6a2782e465600fe2a3ad0c10bd80db2b80a6fb76 --- tools/signapk/src/com/android/signapk/SignApk.java | 88 ++++++++++++++++------ 1 file changed, 65 insertions(+), 23 deletions(-) diff --git a/tools/signapk/src/com/android/signapk/SignApk.java b/tools/signapk/src/com/android/signapk/SignApk.java index dd02b096d..06a8d7f84 100644 --- a/tools/signapk/src/com/android/signapk/SignApk.java +++ b/tools/signapk/src/com/android/signapk/SignApk.java @@ -67,6 +67,7 @@ import java.security.spec.PKCS8EncodedKeySpec; import java.util.ArrayList; import java.util.Collections; import java.util.Enumeration; +import java.util.Iterator; import java.util.Locale; import java.util.Map; import java.util.TreeMap; @@ -116,14 +117,24 @@ class SignApk { private static final int USE_SHA256 = 2; /** + * Minimum Android SDK API Level which accepts JAR signatures which use SHA-256. Older platform + * versions accept only SHA-1 signatures. + */ + private static final int MIN_API_LEVEL_FOR_SHA256_JAR_SIGNATURES = 18; + + /** * Return one of USE_SHA1 or USE_SHA256 according to the signature * algorithm specified in the cert. */ - private static int getDigestAlgorithm(X509Certificate cert) { + private static int getDigestAlgorithm(X509Certificate cert, int minSdkVersion) { String sigAlg = cert.getSigAlgName().toUpperCase(Locale.US); - if ("SHA1WITHRSA".equals(sigAlg) || - "MD5WITHRSA".equals(sigAlg)) { // see "HISTORICAL NOTE" above. - return USE_SHA1; + if ("SHA1WITHRSA".equals(sigAlg) || "MD5WITHRSA".equals(sigAlg)) { + // see "HISTORICAL NOTE" above. + if (minSdkVersion < MIN_API_LEVEL_FOR_SHA256_JAR_SIGNATURES) { + return USE_SHA1; + } else { + return USE_SHA256; + } } else if (sigAlg.startsWith("SHA256WITH")) { return USE_SHA256; } else { @@ -133,10 +144,11 @@ class SignApk { } /** Returns the expected signature algorithm for this key type. */ - private static String getSignatureAlgorithm(X509Certificate cert) { + private static String getSignatureAlgorithm(X509Certificate cert, int minSdkVersion) { String keyType = cert.getPublicKey().getAlgorithm().toUpperCase(Locale.US); if ("RSA".equalsIgnoreCase(keyType)) { - if (getDigestAlgorithm(cert) == USE_SHA256) { + if ((minSdkVersion >= MIN_API_LEVEL_FOR_SHA256_JAR_SIGNATURES) + || (getDigestAlgorithm(cert, minSdkVersion) == USE_SHA256)) { return "SHA256withRSA"; } else { return "SHA1withRSA"; @@ -309,10 +321,24 @@ class SignApk { 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 i = attr.keySet().iterator(); i.hasNext();) { + Object key = i.next(); + if (!(key instanceof Attributes.Name)) { + continue; + } + String attributeNameLowerCase = + ((Attributes.Name) 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")); @@ -438,7 +464,7 @@ class SignApk { /** Sign data and write the digital signature to 'out'. */ private static void writeSignatureBlock( - CMSTypedData data, X509Certificate publicKey, PrivateKey privateKey, + CMSTypedData data, X509Certificate publicKey, PrivateKey privateKey, int minSdkVersion, OutputStream out) throws IOException, CertificateEncodingException, @@ -449,8 +475,9 @@ class SignApk { JcaCertStore certs = new JcaCertStore(certList); CMSSignedDataGenerator gen = new CMSSignedDataGenerator(); - ContentSigner signer = new JcaContentSignerBuilder(getSignatureAlgorithm(publicKey)) - .build(privateKey); + ContentSigner signer = + new JcaContentSignerBuilder(getSignatureAlgorithm(publicKey, minSdkVersion)) + .build(privateKey); gen.addSignerInfoGenerator( new JcaSignerInfoGeneratorBuilder( new JcaDigestCalculatorProviderBuilder() @@ -631,21 +658,23 @@ class SignApk { } private static class CMSSigner implements CMSTypedData { - private JarFile inputJar; - private File publicKeyFile; - private X509Certificate publicKey; - private PrivateKey privateKey; - private OutputStream outputStream; + private final JarFile inputJar; + private final File publicKeyFile; + private final X509Certificate publicKey; + private final PrivateKey privateKey; + private final int minSdkVersion; + private final OutputStream outputStream; private final ASN1ObjectIdentifier type; private WholeFileSignerOutputStream signer; public CMSSigner(JarFile inputJar, File publicKeyFile, - X509Certificate publicKey, PrivateKey privateKey, + X509Certificate publicKey, PrivateKey privateKey, int minSdkVersion, OutputStream outputStream) { this.inputJar = inputJar; this.publicKeyFile = publicKeyFile; this.publicKey = publicKey; this.privateKey = privateKey; + this.minSdkVersion = minSdkVersion; this.outputStream = outputStream; this.type = new ASN1ObjectIdentifier(CMSObjectIdentifiers.data.getId()); } @@ -670,7 +699,7 @@ class SignApk { signer = new WholeFileSignerOutputStream(out, outputStream); JarOutputStream outputJar = new JarOutputStream(signer); - int hash = getDigestAlgorithm(publicKey); + int hash = getDigestAlgorithm(publicKey, minSdkVersion); // Assume the certificate is valid for at least an hour. long timestamp = publicKey.getNotBefore().getTime() + 3600L * 1000; @@ -682,6 +711,7 @@ class SignApk { signFile(manifest, new X509Certificate[]{ publicKey }, new PrivateKey[]{ privateKey }, + minSdkVersion, outputJar); signer.notifyClosing(); @@ -698,7 +728,7 @@ class SignApk { CertificateEncodingException, OperatorCreationException, CMSException { - SignApk.writeSignatureBlock(this, publicKey, privateKey, temp); + SignApk.writeSignatureBlock(this, publicKey, privateKey, minSdkVersion, temp); } public WholeFileSignerOutputStream getSigner() { @@ -708,9 +738,10 @@ class SignApk { private static void signWholeFile(JarFile inputJar, File publicKeyFile, X509Certificate publicKey, PrivateKey privateKey, + int minSdkVersion, OutputStream outputStream) throws Exception { CMSSigner cmsOut = new CMSSigner(inputJar, publicKeyFile, - publicKey, privateKey, outputStream); + publicKey, privateKey, minSdkVersion, outputStream); ByteArrayOutputStream temp = new ByteArrayOutputStream(); @@ -776,6 +807,7 @@ class SignApk { private static void signFile(Manifest manifest, X509Certificate[] publicKey, PrivateKey[] privateKey, + int minSdkVersion, JarOutputStream outputJar) throws Exception { // Assume the certificate is valid for at least an hour. @@ -795,7 +827,7 @@ class SignApk { je.setTime(timestamp); outputJar.putNextEntry(je); ByteArrayOutputStream baos = new ByteArrayOutputStream(); - writeSignatureFile(manifest, baos, getDigestAlgorithm(publicKey[k])); + writeSignatureFile(manifest, baos, getDigestAlgorithm(publicKey[k], minSdkVersion)); byte[] signedData = baos.toByteArray(); outputJar.write(signedData); @@ -807,7 +839,7 @@ class SignApk { je.setTime(timestamp); outputJar.putNextEntry(je); writeSignatureBlock(new CMSProcessableByteArray(signedData), - publicKey[k], privateKey[k], outputJar); + publicKey[k], privateKey[k], minSdkVersion, outputJar); } } @@ -887,6 +919,7 @@ class SignApk { boolean signWholeFile = false; String providerClass = null; int alignment = 4; + int minSdkVersion = 0; int argstart = 0; while (argstart < args.length && args[argstart].startsWith("-")) { @@ -902,6 +935,15 @@ class SignApk { } else if ("-a".equals(args[argstart])) { alignment = Integer.parseInt(args[++argstart]); ++argstart; + } else if ("--min-sdk-version".equals(args[argstart])) { + String minSdkVersionString = args[++argstart]; + try { + minSdkVersion = Integer.parseInt(minSdkVersionString); + } catch (NumberFormatException e) { + throw new IllegalArgumentException( + "min-sdk-version must be a decimal number: " + minSdkVersionString); + } + ++argstart; } else { usage(); } @@ -931,7 +973,7 @@ class SignApk { for (int i = 0; i < numKeys; ++i) { int argNum = argstart + i*2; publicKey[i] = readPublicKey(new File(args[argNum])); - hashes |= getDigestAlgorithm(publicKey[i]); + hashes |= getDigestAlgorithm(publicKey[i], minSdkVersion); } } catch (IllegalArgumentException e) { System.err.println(e); @@ -955,7 +997,7 @@ class SignApk { if (signWholeFile) { SignApk.signWholeFile(inputJar, firstPublicKeyFile, - publicKey[0], privateKey[0], outputFile); + publicKey[0], privateKey[0], minSdkVersion, outputFile); } else { JarOutputStream outputJar = new JarOutputStream(outputFile); @@ -969,7 +1011,7 @@ class SignApk { Manifest manifest = addDigestsToManifest(inputJar, hashes); copyFiles(manifest, inputJar, outputJar, timestamp, alignment); - signFile(manifest, publicKey, privateKey, outputJar); + signFile(manifest, publicKey, privateKey, minSdkVersion, outputJar); outputJar.close(); } } catch (Exception e) { -- 2.11.0