-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Stronger password hashing via sequential memory-hard functions.
--   
--   This package provides bindings to Colin Percival's <a>scrypt</a>
--   implementation (<a>http://www.tarsnap.com/scrypt.html</a>). Scrypt is
--   a key derivation function designed to be far more secure against
--   hardware brute-force attacks than alternative functions such as PBKDF2
--   or bcrypt.
--   
--   Details of the scrypt key derivation function are given in a paper by
--   Colin Percival, Stronger Key Derivation via Sequential Memory-Hard
--   Functions: <a>http://www.tarsnap.com/scrypt/scrypt.pdf</a>.
@package scrypt
@version 0.1.1


-- | Scrypt is a sequential memory-hard key derivation function. This
--   module provides bindings to a fast C implementation of scrypt, written
--   by Colin Percival. For more information see
--   <a>http://www.tarsnap.com/scrypt.html</a>.
module Crypto.Scrypt

-- | Encapsulates the three tuning parameters to the <a>scrypt</a>
--   function: <tt>N</tt>, <tt>r</tt> and <tt>p</tt>. The parameters affect
--   running time and memory usage:
--   
--   <i>Memory usage</i> is approximately <tt>128*r*N</tt> bytes. Note that
--   the <a>params</a> function takes <tt>log_2(N)</tt> as a parameter. As
--   an example, the <a>defaultParams</a>
--   
--   <pre>
--   log_2(N) = 14, r = 8 and p = 1
--   </pre>
--   
--   lead to <a>scrypt</a> using <tt>128 * 8 * 2^14 = 16M</tt> bytes of
--   memory.
--   
--   <i>Running time</i> is proportional to all of <tt>N</tt>, <tt>r</tt>
--   and <tt>p</tt>. However <tt>p</tt> only as an insignificant influence
--   on memory usage an can thus be used to tune the running time of
--   <a>scrypt</a>.
data ScryptParams

-- | Constructor function for the <a>ScryptParams</a> data type
params :: Integer -> Integer -> Integer -> Maybe ScryptParams

-- | Default parameters as recommended in the scrypt paper:
--   
--   <pre>
--   N = 2^14, r = 8, p = 1
--   </pre>
--   
--   Equivalent to <tt><a>fromJust</a> (<a>params</a> 14 8 1)</tt>.
defaultParams :: ScryptParams

-- | Calculates a 64-byte hash from the given password, salt and
--   parameters.
scrypt :: ScryptParams -> Salt -> Pass -> PassHash

-- | Reads a 32-byte random salt from <tt>/dev/urandom</tt>.
getSalt :: IO Salt
newtype Pass
Pass :: ByteString -> Pass
newtype Salt
Salt :: ByteString -> Salt
newtype PassHash
PassHash :: ByteString -> PassHash
instance Show Pass
instance Show Salt
instance Show PassHash
instance Eq PassHash