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Build Status Hex pm

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.

Basic build instructions

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

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

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

Basic usage instructions

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

1> {ok, Salt} = bcrypt:gen_salt().
2> {ok, Hash} = bcrypt:hashpw("foo", Salt).

Verify the password:

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


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.

Original authors

Hunter Morris & Mrinal Wadhwa.