HelloWorldActivity.java

/*
 * Sample application to illustrate tamper detection with DexGuard.
 *
 * Copyright (c) 2012-2014 Saikoa / Itsana BVBA
 */
package com.example;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Gravity;
import android.widget.*;

/**
 * Sample activity that displays "Hello world!". It displays a different
 * message if someone has tampered with the application archive after it has
 * been created by DexGuard.
 *
 * You can experiment with it by first building, installing, and trying the
 * original version:
 *   ant release install
 * You can then tamper with it in some trivial way:
 *   zipalign -f 4 bin/HelloWorld-release.apk HelloWorld-tampered.apk
 *   adb install -r HelloWorld-tampered.apk
 * If you try the application again, you'll see that it detects that it has
 * been modified.
 *
 * Note: some custom firmwares for rooted devices (notably "AvatarRom") apply
 * zipalign when the application is installed, thus triggering the tamper
 * detection. This may or may not be desirable for your application.
 */
public class HelloWorldActivity extends Activity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        new Delegate().checkAndInitialize(this);
    }


    /**
     * This utility class performs the tamper detection and creates the view.
     * We're putting this functionality in a separate class so we can encrypt
     * it, as an extra layer of protection around the tamper detection and
     * some essential code. We can't encrypt the activity itself, for
     * technical reasons, but an inner class or another class are fine.
     */
    private static class Delegate {

        public void checkAndInitialize(Activity activity) {

            // Call the tamper detection in the DexGuard utility library of
            // this sample. The return code is 0 if the application archive is
            // original (created by DexGuard), or non-0 if it has been modified
            // afterwards (by jar, zip, jarsigner, zipalign, or any other tool).
            int check = dexguard.util.TamperDetection.checkApk(activity);

            // Display a message.
            TextView view = new TextView(activity);
            view.setText(check == 0 ?
                             "Hello world!" :
                             "Tamper alert!");
            view.setGravity(Gravity.CENTER);

            // Change the background color if someone has tampered with the
            // application archive.
            if (check != 0)
            {
                view.setBackgroundColor(Color.RED);
            }

            activity.setContentView(view);

            // Briefly display a comment.
            Toast.makeText(activity, 
                           check == 0 ?
                               "The application archive is original" :
                               "The application archive has been modified",
                           Toast.LENGTH_LONG).show();
        }
    }
}