Android 4.2.2 系统签名

这里有原生系统的签名文件platform.pk8和platform.x509.pem以及Signapk工具 。

如果是自己编译的Android系统那么密钥文件在如下位置：

/build/target/product/security/

java -jar signapk.jar  platform.x509.pem platform.pk8 input.apk output.apk

这样编译出来的APK就具有的系统签名，无论是装到/system/app中还是/data/app中都会是。

可以通过以下代码检测本应用是否为系统签名的应用：(来自：https://pankajchunchun.wordpress.com/2014/07/08/how-to-check-if-application-is-system-app-or-not-by-signed-signature/)

import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;

public class AppUtility {

private static final String SYSTEM_PACKAGE_NAME = "android";
private PackageManager mPackageManager = null;

public AppUtility(Context context) {
mPackageManager = (PackageManager) context.getPackageManager();
}

/**
* Match signature of application to identify that if it is signed by system
* or not.
*
* @param packageName
*            package of application. Can not be blank.
* @return <code>true</code> if application is signed by system certificate,
*         otherwise <code>false</code>
*/
public boolean isSystemApp(String packageName) {
try {
// Get packageinfo for target application
PackageInfo targetPkgInfo = mPackageManager.getPackageInfo(
packageName, PackageManager.GET_SIGNATURES);
// Get packageinfo for system package
PackageInfo sys = mPackageManager.getPackageInfo(
SYSTEM_PACKAGE_NAME, PackageManager.GET_SIGNATURES);
// Match both packageinfo for there signatures
return (targetPkgInfo != null && targetPkgInfo.signatures != null && sys.signatures[0]
.equals(targetPkgInfo.signatures[0]));
} catch (PackageManager.NameNotFoundException e) {
return false;
}
}

/**
* Check if application is preloaded. It also check if the application is
* signed by system certificate or not.
*
* @param packageName
*            package name of application. Can not be null.
* @return <code>true</code> if package is preloaded and system.
*/
public boolean isAppPreLoaded(String packageName) {
if (packageName == null) {
throw new IllegalArgumentException("Package name can not be null");
}
try {
ApplicationInfo ai = mPackageManager.getApplicationInfo(
packageName, 0);
// First check if it is preloaded.
// If yes then check if it is System app or not.
if (ai != null
&& (ai.flags & (ApplicationInfo.FLAG_SYSTEM | ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0) {
// Check if signature matches
if (isSystemApp(packageName) == true) {
return true;
} else {
return false;
}
}
} catch (NameNotFoundException e) {
e.printStackTrace();
}
return false;
}
}