Valve Anticheat ( VAC )

Reversing VAC3 is a pretty fun endeavour, I first looked into it after reading some posts by: The Raptor Factor, on his site (Here). There aren't very many amazing techniques employed to make the modules harder to reverse, its pretty much all security through obscurity. Some really terrible string encryption for imports, and deeper into the modules all strings are encrypted by a single byte xor (lmao!).

In fact, it's pretty trivial to make an IDA script to decrypt them all for you in one go, one script could fix all imports for any VAC3 module, another could fix all their xor'd strings if you want to go that far, but for my case I just did them all inline. Example:

But with this information, you can pretty much render all but one VAC3 module obsolete, Comme Ce...