And what do they hit to make sure the password was cracked? Do they make bots to login? I don't understand.
How else would you verify that the password matches ?
The output of your library's BcryptEncoder.encode(password) includes not only the password hash but information about the algorithm and the salt. That's what you store in your database. That extra information tells the decode function how to decode later on.
See here:
http://stackoverflow.com/questions/6832445/how-can-bcrypt-ha...