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erlang-bcrypt is a wrapper around the OpenBSD Blowfish password hashing algorithm, as described in "A Future-Adaptable Password Scheme"_ by Niels Provos and David Mazieres.

.. _"A Future-Adaptable Password Scheme": http://www.openbsd.org/papers/bcrypt-paper.ps

1. Build it (project uses rebar, but I've included a Makefile)::

    make
   

2. Run it (simple way, starting sasl, crypto and bcrypt)::

    erl -pa ebin -boot start_sasl -s crypto -s bcrypt
   

3. Hash a password using a salt with the default number of rounds::

    1> {ok, Salt} = bcrypt:gen_salt().
    {ok,"$2a$12$sSS8Eg.ovVzaHzi1nUHYK."}
    2> {ok, Hash} = bcrypt:hashpw("foo", Salt).
    {ok,"$2a$12$sSS8Eg.ovVzaHzi1nUHYK.HbUIOdlQI0iS22Q5rd5z.JVVYH6sfm6"}
   

4. Verify the password::

    3> {ok, Hash} =:= bcrypt:hashpw("foo", Hash).
    true
    4> {ok, Hash} =:= bcrypt:hashpw("bar", Hash).
    false
   

The bcrypt application is configured by changing values in the application's environment:

default_log_rounds Sets the default number of rounds which define the complexity of the hash function. Defaults to 12.

mechanism Specifies whether to use the NIF implementation ('nif') or a pool of port programs ('port'). Defaults to 'nif'.

Note: the NIF implementation no longer blocks the Erlang VM scheduler threads

pool_size Specifies the size of the port program pool. Defaults to 4.

• Hunter Morris_
• Mrinal Wadhwa_

.. _Hunter Morris: http://github.com/skarab

.. _Mrinal Wadhwa: http://github.com/mrinalwadhwa