You can be surprised if you like. But it was novel enough to prevent my game from ever being pirated. [1]
>If only because they just have to find its code and nop it out.
If they changed a single byte in the executable, then none of the encrypted data files (i.e., the actual game) would load. I used a cryptographic key generated from the signature of the binary.
More than one byte would need to be changed. :)
I know I just raised the bar, but due to that feature and the additional obfuscation and misdirection I added, no one ever cracked it. I'm sure that the bar has been raised higher on commercial PC apps (self modifying anti-debugger code comes to mind), but what I did was at least novel on Android.
My technique was dead in the water on iOS, unfortunately; Apple mucks with the binary (encrypts it?) in the production version. But no one pirates on iOS anyway, right? ;)
[1] Successfully, I should say. Pirates thought they'd hacked the game and uploaded it all over the various pirate web sites multiple times. Thing is that the game always detected that it had been pirated, and as a result it downgraded to the "free demo" behavior, so people downloaded the same app they could have gotten for free from the store.
Why don't you make that a product? Esp the downgrade to demo, it is a great feature.
I am sure you could take the signature of the executable in memory and create a key from that for iOS? You just can't _write_ to executable memory but you can read it.
>If only because they just have to find its code and nop it out.
If they changed a single byte in the executable, then none of the encrypted data files (i.e., the actual game) would load. I used a cryptographic key generated from the signature of the binary.
More than one byte would need to be changed. :)
I know I just raised the bar, but due to that feature and the additional obfuscation and misdirection I added, no one ever cracked it. I'm sure that the bar has been raised higher on commercial PC apps (self modifying anti-debugger code comes to mind), but what I did was at least novel on Android.
My technique was dead in the water on iOS, unfortunately; Apple mucks with the binary (encrypts it?) in the production version. But no one pirates on iOS anyway, right? ;)
[1] Successfully, I should say. Pirates thought they'd hacked the game and uploaded it all over the various pirate web sites multiple times. Thing is that the game always detected that it had been pirated, and as a result it downgraded to the "free demo" behavior, so people downloaded the same app they could have gotten for free from the store.