How to go from cracked APK to java code? 1-click tool cracked my app

Question

So I published my android app, I proguarded it, applied LVL and even changed some of the LVL code but offcourse, I found it cracked somewhere using a tool called Lucky Patcher. I am not going to ask how can I protect against 1 click tools like that, as I guess there is no single answer ( unless you have an idea and can point me toward).

I need to ask you to help figure out how my code was cracked. I understand that this tool takes APK file and removes licensing. Now given that, how can I take this APK file and reverse engineer it back to Java files to see how the tool cracked my code (so I fix it)

Please help me Thanks

Answer 1

After Proguard, there's no way to decompile your code into humanly-readable Java.
While it makes the reverse engineering process more difficult, it's not impossible for a clever reverser to figure out the hidden algorithm.

As for tools,
Use android-apktool to decompile to smali and extract all the encoded xml resources.
Use dex2jar to translate Dalvik into jar and finally jd-gui to see the resulting reversed java code

Answer 2

There's a lot of info here on how to go from a DEX file back to Java source. Also, have you looked at this blog post which addresses many of the ways to protect your source?