Safe Haskell | None |
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Implementation of Password Based Key Derivation Function, from RSA labs.

See PKCS # 5 / RFC 2898 from rsa labs: and haskell cafe discussion on why password hashing is a good idea for web apps and a suggestion that this be implemented:

http://www.ietf.org/rfc/rfc2898.txt http://groups.google.com/group/fa.haskell/browse_thread/thread/66c7aeeb6e47764a/b15d9d74d68c002c

hashedpass = pbkdf2 ( Password . toOctets $ "password" ) ( Salt . toOctets $ "salt" )

- pbkdf2 :: Password -> Salt -> HashedPass
- pbkdf2' :: ([Word8] -> [Word8] -> [Word8], Integer) -> Integer -> Integer -> Password -> Salt -> HashedPass
- newtype Password = Password [Word8]
- newtype Salt = Salt [Word8]
- newtype HashedPass = HashedPass [Word8]
- toOctets :: Binary a => a -> [Word8]
- fromOctets :: Binary a => [Word8] -> a

# Documentation

pbkdf2 :: Password -> Salt -> HashedPassSource

A reasonable default for rsa pbkdf2.

pbkdf2 = pbkdf2' (prfSHA512,64) 5000 64

SHA512 outputs 64 bytes. At least 1000 iters is suggested by PKCS#5 (rsa link above). I chose 5000 because this takes my computer a little over a second to compute a simple key derivation (see t test function in source)

Dklen of 64 seemed reasonable to me: if this is being stored in a database, doesn't take too much space.

Computational barriers can be raised by increasing number of iters

pbkdf2' :: ([Word8] -> [Word8] -> [Word8], Integer) -> Integer -> Integer -> Password -> Salt -> HashedPassSource

Password Based Key Derivation Function, from RSA labs.

pbkdf2' (prf,hlen) cIters dklen (Password pass) (Salt salt)

prf: pseudo random function

hlen: length of prf output

cIters: Number of iterations of prf

dklen: Length of the derived key (hashed password)

newtype HashedPass Source

fromOctets :: Binary a => [Word8] -> aSource