Copy-protection traps

Question

Just about to release a free version of my app and I'm looking towards the free-mium model to give extra options to users. However, I'm definitely worried about it being pirated too quickly for me to make any anything.

Does anybody have some quality copy-protection techniques for Android? And I'm not talking about the pos LVL that is provided. I'm looking for some sneaky traps to detect if my code has been tampered with. Any ideas welcome; gotta make it hard enough on them that its just not worth it.

Answer 1

It will only get pirated if it's popular, so you have a long way to go :). Generally, obfuscate your code, don't use the LVL as is since there are tools that disable it automatically. Not sure what your idea of a 'sneaky trap' is, but watch this for some ideas on how to protect your app.

Those are mentioned in the video, but:

• use ProGuard to obfuscate your code
• to detect if your code has been changed, you can check the CRC of classes.dex or check if the APK has been signed with your certificate (if someone changes your code, they'll have to resign it). However the antilvl tool effectively disables the APIs you would use to check for tampering. So you need to do it in native code if you want it to be effective.
• don't do your checks on startup, but later on so they are harder to detect.
• if possible, have a server side component to your license/tampering checking. Think about how your app should behave if there is no network connection. Cache server responses? For how long? Deny access right away? Allow access always?, etc.

Answer 2

Protection can always be broken, all you can do is make it harder to break. Something you might do would be writing some essential part(s) of your code in C and call it via the NDK. Then you can do some testing in there, because decompiling the C part will be much harder than decompiling bytecode.

Answer 3

You can use ProGuard in eclipse to obfuscate your code. It optimizes, and obfuscates your code by removing unused code and renaming classes, fields, and methods with semantically obscure names. The result is a smaller sized .apk file that is more difficult to reverse engineer. That way your code will be more tamper proof.

Reference : developer.android