android APK签名过程之MANIFEST.MF分析
一、手工验证
用winrar打开签名过的apk包，发现多了一个META-INF文件夹：
解压缩后打开META-INF目录，有三个文件：MANIFEST.MF，CERT.SF，CERT.RSA
本文只讲解MANIFEST.MF的生成，用记事本打开MANIFEST.MF文件：
Manifest-Version: 1.0Created-By: 1.0 (Android) Name: res/drawable-xhdpi/ic_launcher.png SHA1-Digest: AfPh3OJoypH966MludSW6f1RHg4= Name: res/menu/main.xml SHA1-Digest: wXc4zBe0Q2LPi4bMr25yy5JJQig= Name: AndroidManifest.xml SHA1-Digest: k3QiLyii25nxkE9q59pXGWI2aTo= Name: res/drawable-mdpi/ic_launcher.png SHA1-Digest: RRxOSvpmhVfCwiprVV/wZlaqQpw= Name: res/drawable-hdpi/ic_launcher.png SHA1-Digest: Nq8q3HeTluE5JNCBpVvNy3BXtJI= Name: res/layout/activity_main.xml SHA1-Digest: qVW+nHovqmEmKpssXKUBidrNDDA= Name: resources.arsc SHA1-Digest: luJu2wwHeH7XAJwms2gIq/pco40= Name: lib/armeabi/libhello-jni.so SHA1-Digest: uFb6Vfi3T/Rq0dvjgCqW7fKKrzM= Name: classes.dex SHA1-Digest: zaipAFvc+AzMSc2nJJG9zIrrfqE= Name: res/drawable-xxhdpi/ic_launcher.png SHA1-Digest: GVIfdEOBv4gEny2T1jDhGGsZOBo=
以文件res/menu/main.xml做验证，用HashTab查看该文件的SHA-1值是C17738CC17B44362CF8B86CCAF6E72CB92494228
复制该二进制串到WINHEX中：
使用“Base64编码解码工具”对此二进制文件计算base64编码：
打开输出文件中的base64编码为：
wXc4zBe0Q2LPi4bMr25yy5JJQig=
是和MANIFEST.MF文件中res/menu/main.xml对应的SHA1-Digest值是一样的。
也就是说MANIFEST.MF中保存了所有其他文件的SHA-1并base64编码后的值。
二、android源码验证
打开android源码build/tools/signapk/SignApk.java分析，没有下载android源码的可以在线参考： https://github.com/OESF/Embedded-Master-MIPS/blob/370863733b500b7f0ded111f4b800bce990d69a5/build/tools/signapk/SignApk.java
// MANIFEST.MF Manifest manifest = addDigestsToManifest(inputJar); je = new JarEntry(JarFile.MANIFEST_NAME); je.setTime(timestamp); outputJar.putNextEntry(je); manifest.write(outputJar);
/** Add the SHA1 of every file to the manifest, creating it if necessary. */
private static Manifest addDigestsToManifest(JarFile jar) 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)");
}
BASE64Encoder base64 = new BASE64Encoder();
MessageDigest md = MessageDigest.getInstance("SHA1"); 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<String, JarEntry>(); 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() && !name.equals(JarFile.MANIFEST_NAME) &&
!name.equals(CERT_SF_NAME) && !name.equals(CERT_RSA_NAME) &&
(stripPattern == null ||
!stripPattern.matcher(name).matches())) {
InputStream data = jar.getInputStream(entry); while ((num = data.read(buffer)) > 0) {
md.update(buffer, 0, num);
}
Attributes attr = null; if (input != null) attr = input.getAttributes(name);
attr = attr != null ? new Attributes(attr) : new Attributes();
attr.putValue("SHA1-Digest", base64.encode(md.digest()));
output.getEntries().put(name, attr);
}
} return output;
}
也可以看出MANIFEST.MF中保存了所有其他文件的SHA-1并base64编码后的值。