en/decrypting dlls for protection?

[Dreglor]

i was thinking about en/decryption methods and how to prevent cracking of them

then the idea came in,
lets say if your making a game and you are required to enter a key (like most games now) during install and/or frist time playing the game, what if you had the keysystem in a dll and it was encrypted so that it will be unuseable and it would require the client to decrypted it. then when done it will be encrpyted again

but the only problem is if there was a bug in the encryption system on the client then poof... readonly would solve this but you would create a copy in memory (and some how use it) or make a copy which sounds easy to get through

i haven't try this idea before but it sounds intresting, no?

[Rings]

sorry, is that what you wrote a tip or a trick ?
plz post only code here, not questions. thx
(and forum-admin, you can move this )