python-bcrypt is a Python wrapper of OpenBSD's Blowfish password hashing
code, as described in "A Future-Adaptable Password Scheme" by Niels
Provos and David Mazières.

This system hashes passwords using a version of Bruce Schneier's Blowfish
block cipher with modifications designed to raise the cost of off-line
password cracking and frustrate fast hardware implementation. The
computation cost of the algorithm is parametised, so it can be increased
as computers get faster. The intent is to make a compromise of a password
database less likely to result in an attacker gaining knowledge of the
plain-text passwords (e.g. using John the Ripper).