3 ms·
Speeding up your password hash mechanism makes it weaker. The faster your password hash system, the more quickly your password list can be broken. This is pro
by ghshephard 12y ago
Speeding up your password hash mechanism makes it weaker. The faster your password hash system, the more quickly your password list can be broken.
This is probably the best commentary I've seen on the topic of how many rounds you should incorporate into your KDF (Scrypt/Bcrypt/PBKDF2 all let you dial as many as you wish), so I won't try and improve on it: http://security.stackexchange.com/a/3993 http://security.stackexchange.com/a/3993
- atoponce 12y agoYou're overlooking the entropy behind the hash though. If entropy is sufficient for creating the password (120-bits or so), no matter of brute force speed will recover the text that created the hash. You'll instead need to break the hashing algorithm itself. The math is against you.
- deleted 12y ago[deleted]
- ghshephard 12y agoIf you have 120 bits of entropy, then a single round of unsalted SHA-2 is sufficient. If you have typical users, with typical user passwords, then take a few minutes to read through: http://security.stackexchange.com/a/3993 http://security.stackexchange.com/a/3993 (it discusses the importance of taking into account entropy) to determine what work factor is appropriate for your situation, then just deploy one of scrypt/bcrypt/PBKDF2 with that work factor.
- tptacek 12y agoYes. The basic job of a password hash is to improve the security of low-entropy secrets. The argument here seems to be that if people simply don't use passwords, but instead secure AES keys, password hashes won't matter. Ok, but we're talking about passwords, and so was he, upthread.