pbkdf2

Creates strong passwords from weaker ones, using PBKDF2 (RFC 2898) and scrypt (which builds on PBKDF2).

PBKDF2 makes the strong password resistant to attackers who have more computing power than you. Scrypt makes the strong password more resistant to attackers who have more memory bandwidth than you.

PBKDF2 was a good solution a decade ago, but modern GPUs and ASICs have made it relatively inexpensive to put together something with raw computing power many times more powerful than an expensive CPU.

On the other hand memory bandwidth is going in the other direction. Modern CPUs excel at memory bandwidth. Custom ASICs have two orders of magnitude less of an advantage over CPUs in memory bandwidth compared with the advantage they can have in compute power.

Despite its name, Pbkdf2's unique ability isn't creating PBKDF2-derived passwords, it's making it easy to create Scrypt-derived passwords.

All available documentation can be read online at http://pbkdf2.sourceforge.net