I personally wonder about the difficulty of discovering someone's private key in their wallet.dat by brute force attack. I think this would require 2256 hashes to guarantee finding the private key with an average crack time of 2255 hashes. Can anybody familiar with cryptography answer that question and/or elaborate?
If you're trying to break the private key, forget the hashes. A Bitcoin address is a hash of the public key, which you already know, so there's no point in trying to break that hash. I'm sure there's plenty of literature on the web about how long it would take to find a private key by brute force.