Lucky patcher, how can I protect from it? [duplicate]

Question 1

Code to check your certificate:

public void checkSignature(final Context context) {
    try {
        Signature[] signatures = context.getPackageManager().getPackageInfo(context.getPackageName(), PackageManager.GET_SIGNATURES).signatures;

        if (signatures[0].toCharsString() != <YOUR CERTIFICATE STRING GOES HERE>) {
            // Kill the process without warning. If someone changed the certificate
            // is better not to give a hint about why the app stopped working
            android.os.Process.killProcess(android.os.Process.myPid());
        }
    } 
    catch (NameNotFoundException ex) {
        // Must never fail, so if it does, means someone played with the apk, so kill the process
        android.os.Process.killProcess(android.os.Process.myPid());
    }
}

Next how to find which one is your certificate. You must produce an APK, in release mode, as the debug certificate is different from the release one. Output your certificate into your Logcat:

signatures[0].toCharsString();

Remember that when you are back to debug mode, the certificate is different again. To avoid debug issues use next line to skip the verification:

if ((context.getApplicationContext().getApplicationInfo().flags &= ApplicationInfo.FLAG_DEBUGGABLE) != 0)
    return;

Next the lucky patcher checker. I decompiled all versions of Lucky Patcher, and I've found that its creator used 2 package names between all realeases. So you only need to keep track of new versions and keep adding future package names.

private boolean checkLuckyPatcher() {
    if (packageExists("com.dimonvideo.luckypatcher"))
        return true;

    if (packageExists("com.chelpus.lackypatch"))
        return true;

    if (packageExists("com.android.vending.billing.InAppBillingService.LACK"))
        return true;

    return false;
}

private boolean packageExists(final String packageName) {
    try {
         ApplicationInfo info = this.getPackageManager().getApplicationInfo(packageName, 0);

        if (info == null) {
            // No need really to test for null, if the package does not
            // exist it will really rise an exception. but in case Google
            // changes the API in the future lets be safe and test it
            return false;
        }

        return true;
    }
    catch (Exception ex) {
        // If we get here only means the Package does not exist
    }

    return false;
}

Question 2

As of current version (6.4.6), Lucky Patcher generates very short token. For example, real purchase token:

felihnbdiljiajicjhdpcgbb.AO-J1OyQgD6gEBTUHhduDpATg3hLkTYSWyVZUvFwe4KzT3r-O7o5kdt_PbG7sSUuoC1l6dtqsYZW0ZuoEkVUOq5TMi8LO1MvDwdx5Kr7vIHCVBDcjCl3CKP4UigtKmXotCUd6znJ0KfW

And that is Lucky Token:

kvfmqjhewuojbsfiwqngqqmc

Pretty straight forward solution is to check string length of token

@Override public void onIabPurchaseFinished(IabResult result, Purchase info) {
    if (info.getToken().length < 25) {
        Log.wtf("PIRATE", "PIRATE DETECTED");
        return;
    }
}

Question 3

Implement a function that gets called under certain actions, and which checks whether the LuckyPatcher package is installed in the device.

If found, then exit your app. Don’t allow to use it regardless if is paid or not, better bad reviews than thousands of illegal copies. Alternatively you could show a message stating that LuckyPatcher has been found and the app can't run.

If your app gets patched by LuckyPatcher, meaning that it has hacked your LVL implementation, then at least your app will not execute due to the LuckyPatcher package detection.

Question 4

A way, is to check if lucky patcher is installed and if so, then show a message to the user, and kill your process afterwards. If a user has it, means he is trying to crack your software or other developer's one. So better not to allow to use your app in a phone that has it installed. Fight piracy.

Question 5

Whenever Lucky Patcher creates a modded APK file, it always ends up with a different package name, as you can't run two apps under the same package name.

Here's a simple solution that checks if your code is running under the wrong package name:

PackageManager pm = getPackageManager();

try {
    PackageInfo packageInfo = pm.getPackageInfo("YOUR_PACKAGE_NAME",PackageManager.GET_ACTIVITIES);
} catch (PackageManager.NameNotFoundException e){
    finish(); 
    //If you get here, your code is running under a different package name... Kill the process!
}

I just call finish(); on my app and I can't break it, but it might be best to use android.os.Process.killProcess(android.os.Process.myPid()); as @PerracoLabs suggested.