Password-based cryptography


Password-based cryptography generally refers to two distinct classes of methods:
Some systems attempt to derive a cryptographic key directly from a password. However, such practice is generally ill-advised when there is a threat of brute-force attack. Techniques to mitigate such attack include passphrases and iterated password-based key derivation functions such as PBKDF2.

Multi-party methods

systems allow
two or more parties that agree on a password
to derive shared keys without exposing the password or keys to network attack.
Earlier generations of challenge-response authentication systems
have also been used with passwords, but these have generally
been subject to eavesdropping and/or brute-force attacks on the password.