2.4 Patch CRC check. After changing the Asprotect.exe file. The CRC check of encrypted data is also changed. Launch ollydbg with new modified Asprotect.exe. Let’s patch it. Press CTRL+S to find sequence of commands in Asprotect dll section mov ebx, [eax] mov eax, esi We have found the sequence of commands [/code] 010C8786 mov ebx,dword ptr ds:[eax] 010C8788 mov eax,esi 010C878A call 010ABA88 010C878F add eax,dword ptr ds:[10D4188] 010C8795 call 010C859C 010C879A mov dword ptr ds:[10D4180],eax 010C879F xor ebx,dword ptr ds:[10D4184] 010C87A5 cmp ebx,dword ptr ds:[10D4180] 010C87AB je short 010C87B1 [/code] Set breakpoint on 010C879Fh, Press SHIFT+F9, we break on 010C879Fh. EBX is a CRC Value which can be located in Asprotect.exe file. The new CRC value is [10D4184h] XOR [10D4180h], replace old value with new value in Asprotect.exe file. Now everything is OK! HOHO, we are able to make keygen for our ‘new Asprotect application’.
