Ruby/Password

Ruby/Password is a suite of password handling methods for Ruby. It supports the manual entry of passwords from the keyboard in both buffered and unbuffered modes, password strength checking, random password generation, phonemic password generation (for easy memorisation by human-beings) and the encryption of passwords.

From the CrackLib README:

CrackLib makes literally hundreds of tests to determine whether you've chosen a bad password.

• It tries to generate words from your username and GECOS entry and tries to match them against the password you've chosen.
• It checks for simplistic patterns.
• It then tries to reverse-engineer your password into a dictionary word, and searches for it in your dictionary.

- after all that, it's PROBABLY a safe(-ish) password. 8-)

The target audience for this library is system administrators who need to write Ruby programs that prompt for, generate, verify and encrypt passwords.