the big call >> mov eax,01 ret

The simple compares only exist if the author wrote their code in this fashion

poor, but basic example:

global registered = false; //reference throughout code

doSerialCheck(){
.....
if(all_checks_passed) registered = true;

}

If for instance a hash is always compared or some other method is used then this simple move-and-compare-boolean check no longer really exists. Granted you can typically always reduce a patch to something very small or similar in nature but I think you see my point.

Cheers

[leosmi05]

Maybe you could try to patch the file and let it make all the decrypting and CRC checking on a backup of the original file. This way it would bypass some tricky decompressing routines which are using the calculated CRC to generate decompressed code.