My idea isnt hacker proof, but might remove some of the interest for hacking the game.
1) Make the first 5-10 levels free so people can learn the game and have some fun without paying. Less will want to hack the first level and the game will spread even further by Freemium model.
2) Let part of the game levels or logic stay online. Eg. when reaching for level 5 or 10 or 15, then download small parts for the game, and every time submit the progress-log from the game and validate this against possible values + hashcodes. This could perhaps make it possible to automatically close down of hacked accounts.
Stealth cheater protection
3) You could also just count “small warning flags” that you place around in the game. Dont just check for the “validation” in the beginning, no build these flags into the game logic itself. Dont make it break the gameplay, because then noone will look for it.
Then when the user reached the end of level monster, check if there were any logged warning flags. These will not show up inside the game, so the unknowing user with a hacked edition could be playing for hours/days and suddently realize that he/she couldnt finish the game or advance to next level, because the game had a “bug”. What the user didnt know was that this bug only occures on hacked clients.
Be smarter than the crackers. Fool them into thinking the job was done. Make a copyprotection and know that the more advanced crackers will be able to remove it. But they probably dont want to play 50 levels to check if the crack also works all the way.
Once they realize this problem, they might start to crack it too. But if you break the game up into level-packs, you can still validate between each pack download. So once you receive hacked client hash data, then just execute an exeception and crash the game on the client. Whoops the game crashed. Dont tell its because its hacked. A program error can happend. 🙂
Again, its not hacker proof. But it might annoy them enough to move on to the next game. Lastly, you could also put out regular updates for the game and only the latest version should be able to “post the records” etc. so the active users would have to update to keep in the loop.
I have been doing some apk decompiling and hacking for a while (not warez, but mods and hacks mostly to the google apps and the android framework, always abiding xda-developers policies).
Once you learn to read smali, it is almost as reading the original java code (but with way more LOCs). So, any code you add to check for keys can be found and deleted or replaced. You don’t even need to recompile each time to eliminate more than one (some searches do miracles to find similar pieces of code) and, even if compilation/recompilation cycles are needed to find them, it’s just a matter of one or two minutes to decompile: everything is automated by apktool and even more by apkmanager.
Having said that, my suggestion to you is to implement some sort of online scoring table or similar, and when the user looks at the score table online, you can check the hash code you implemented and compare it with the associated gmail account. That way you can report the hack to google and send a nasty message to the user of the warez, explaining why that is illegal.
Of course, a new hack could be implemented to eliminate the scoring table, but that would reduce the interest for the warez.
After researching to answer this question: Injecting code into APK (really about the Amazon DRM mechanism), I can tell a little bit on how Amazon is protecting the apps: it includes methods for checking for the installation validity everywhere (you can see an example of how they do it in my answer to that question). This will make any attempt to hack an app not very difficult, but extremely tedious. I believe that is a strong point: hackers won’t want to spend so much time doing so many repetitive tasks: it’s not challenging and it’s boring. The main flaw I see in that approach is the possibility to hack the Amazon app itself to always return a valid answer, of course. But, if you mix your current hash checks with some sort of online check scattered among your methods, I believe the chances of it getting hacked may be drastically reduced.
Taken from my solution from this post Avoid apk cracked
Implement your own licensing library
I’d also refer you to check out this from Google I/O 2011 YouTube recording:
Evading Pirates and Stopping Vampires
The Presentation Notes from Evading Pirates and Stopping Vampires
Some basic keypoints
- Modify the LVL
- Implement LVL Tamper Resistance
- Use obfuscation
- Add reflection