md5 are hashes, which means that they are made to 'hash' text, sort of a one way encryption. You can 'encrypt' it to md5, but not back. This means you can only verify the password if you have the original one given, so if they hack your database the hackers don't really have a password they can use to crack other accounts which might use the same password. Either way, md5 is a seriously flawed algo, and shouldn't be used anymore. It is possible to 'crack' md5 hashes, and it's not that hard either, I wouldn't advise you to crack your own servers hashes, because that would be very dumb, and there would no reason for you to have them, other than shady stuff...