I used emacs hexl-mode and http://support.amd.com/TechDocs/24594.pdf to edit a je to a jne which caused the program to think I put in the correct password. That was fun.
But it doesn't work anymore with the correct password...
I always found it was cleaner to either force (jmp) or remove (nopnop) the jump rather than inversing its condition. It's more explicit.
Also, in the real world, cracking's usually a bit more than finding the right jump to force/remove. Although, if it's enough to reach your goal, you should do it.
