-- |
-- Module : Crypto.ConstructHash.MiyaguchiPreneel
-- License : BSD-style
-- Maintainer : Kei Hibino <ex8k.hibino@gmail.com>
-- Stability : experimental
-- Portability : unknown
--
-- provide the hash function construction method from block cipher
-- <https://en.wikipedia.org/wiki/One-way_compression_function>
--
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Crypto.ConstructHash.MiyaguchiPreneel
( compute, compute'
, MiyaguchiPreneel
) where
import Data.List (foldl')
import Crypto.Data.Padding (pad, Format (ZERO))
import Crypto.Cipher.Types
import Crypto.Error (throwCryptoError)
import Crypto.Internal.ByteArray (ByteArrayAccess, ByteArray, Bytes)
import qualified Crypto.Internal.ByteArray as B
newtype MiyaguchiPreneel a = MP Bytes
deriving (ByteArrayAccess)
instance Eq (MiyaguchiPreneel a) where
MP b1 == MP b2 = B.constEq b1 b2
-- | Compute Miyaguchi-Preneel one way compress using the supplied block cipher.
compute' :: (ByteArrayAccess bin, BlockCipher cipher)
=> (Bytes -> cipher) -- ^ key build function to compute Miyaguchi-Preneel. care about block-size and key-size
-> bin -- ^ input message
-> MiyaguchiPreneel cipher -- ^ output tag
compute' g = MP . foldl' (step $ g) (B.replicate bsz 0) . chunks . pad (ZERO bsz) . B.convert
where
bsz = blockSize ( g B.empty {- dummy to get block size -} )
chunks msg
| B.null msg = []
| otherwise = (hd :: Bytes) : chunks tl
where
(hd, tl) = B.splitAt bsz msg
-- | Compute Miyaguchi-Preneel one way compress using the infered block cipher.
-- Only safe when KEY-SIZE equals to BLOCK-SIZE.
--
-- Simple usage /mp' msg :: MiyaguchiPreneel AES128/
compute :: (ByteArrayAccess bin, BlockCipher cipher)
=> bin -- ^ input message
-> MiyaguchiPreneel cipher -- ^ output tag
compute = compute' $ throwCryptoError . cipherInit
-- | computation step of Miyaguchi-Preneel
step :: (ByteArray ba, BlockCipher k)
=> (ba -> k)
-> ba
-> ba
-> ba
step g iv msg =
ecbEncrypt k msg `bxor` iv `bxor` msg
where
k = g iv
bxor :: ByteArray ba => ba -> ba -> ba
bxor = B.xor