Simple bcrypt wrapper for Lua.

Please note that this depends on bcrypt, which AFAIK is only included in the base system on OpenBSD. I have not yet successfully built it on Linux, but will add a Makefile if I get it to build on Debian. (At a glance, Debian does not appear to have a package for a crypt library with bcrypt.)

Basic usage:

require "bcrypt"
-- Defaults to a cost of 8, higher will take (much, much...) longer.
local salt = bcrypt.gensalt(8)
local hash = bcrypt.bcrypt("my password", salt)

-- Print the contents. You can just save hash.raw; bcrypt.equal
-- can take the raw string or the derived table.
for k,v in pairs(hash) do print("--> ", k,v) end
--> raw	$2a$07$8BzFlUuprZN4FSBpDx3ZAuPWOu4CZ3uv8Awa4EjAZhNmnIY59nh2e
--> salt	8BzFlUuprZN4FSBpDx3ZAu
--> version	2a
--> cost	7

-- Later, somebady wants to log in, check if the password matches.
if bcrypt.equal("my password", hash) then print "OK" end --> "OK"
if not bcrypt.equal("not my password", hash) then print "REJECTED" end --> "REJECTED"