More than some, I think. Most strong crypto short of one-time pads makes use of NP (or at least problems solvable by NP problems, factoring is probably a littl

More than some, I think. Most strong crypto short of one-time pads makes use of NP (or at least problems solvable by NP problems, factoring is probably a little easier than NP). NP is nice for crypto since it has P time checkable solutions - so just make the "password" an encoding of the solution and you're golden. It's easy to check that a password is correct, and it takes EXP time to brute force. Hopefully the crypto implementation blocks IPs after some number of login attempts that is less than EXP :)