Securely hash and check passwords using PBKDF2.

    Use random salts to protect againt rainbow tables, many iterations against
    brute-force, and constant-time comparaison againt timing attacks.

    Keep parameters to the algorithm together with the hash so that we can
    change the parameters and keep older hashes working.

    See more details at http://exyr.org/2011/hashing-passwords/

    Author: Simon Sapin
    License: BSD

    pbkdf2
    ~~~~~~

    This module implements pbkdf2 for Python.  It also has some basic
    tests that ensure that it works.  The implementation is straightforward
    and uses stdlib only stuff and can be easily be copy/pasted into
    your favourite application.

    :copyright: (c) Copyright 2011 by Armin Ronacher.
    :license: BSD, see LICENSE for more details.