It might be that he has already entered the code? Maybe instead of just saying that a code is invalid, it should specify that the item has already been unlocked?

@bourne, how about we chat over gmail / gmail chat? Amarcoli@ucsc is where you can get ahold of me, if you have a gmail as well we can use gmail chat.

Good job on the encryption, I still managed to get hold of the private key though :) Haven't unlocked everything yet, but if you like we could talk offline about how I got it and work towards making it more secure if you are interested.