This library is based on Ricardo Garcia's wrapper of Solar Designer's implementation of "A future-adaptable password scheme" by Niels Provos and David Mazières.
Two routines, bcrypt_gensalt() and bcrypt_hashpw(), are all that's needed for hashing and verifying passwords. See test.c and bcrypt.h for an explanation of their use.
You can safely store the hashed password in a database as the expected computational effort to brute-force the hashing scheme is on the order of several years for current (2011) hardware and a decent password.
A password such as "$2a$10$VEVmGHy4F4XQMJ3eOZJAUeb.MedU0W10pTPCuf53eHdKJPiSE8sMK" is comprised of a prefix "$2a" identifying it as a bcrypt password, an integer "10" which specifies the "work factor" (i.e. how many passes of the Blowfish algorithm to use), a salt "VEVmGHy4F4XQMJ3eOZJAUe" which should be unique for each password stored, and the hashed password "b.MedU0W10pTPCuf53eHdKJPiSE8sMK" encoded in base-64.
This code is released in the public domain.