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Skein256.hs
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/
Skein256.hs
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{-# LANGUAGE ForeignFunctionInterface #-}
-- |
-- Module : Data.CryptoHash.Skein256
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : unknown
--
-- A module containing Skein256 bindings
--
module Data.CryptoHash.Skein256 (
Ctx(..),
-- * Incremental hashing Functions
init, -- :: Int -> Ctx
update, -- :: Ctx -> ByteString -> Ctx
finalize, -- :: Ctx -> ByteString
-- * Single Pass hashing
hash, -- :: Int -> ByteString -> ByteString
hashlazy -- :: Int -> ByteString -> ByteString
) where
import Prelude hiding (init)
import Foreign
import Foreign.C.String
import Foreign.C.Types
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
import Data.ByteString (ByteString)
import Data.ByteString.Unsafe (unsafeUseAsCStringLen, unsafeIndex)
import Data.ByteString.Internal (create)
data Ctx = Ctx !ByteString
sizeCtx :: Int
sizeCtx = 160
instance Storable Ctx where
sizeOf _ = sizeCtx
alignment _ = 16
poke ptr (Ctx b) = do
mapM_ (\i -> poke (ptr `plusPtr` i) (unsafeIndex b i)) [0..(sizeCtx-1)]
peek ptr = do
b <- create sizeCtx (\bptr -> do
mapM_ (\i -> do
f <- peek (ptr `plusPtr` i) :: IO Word8
poke (bptr `plusPtr` i) f
) [0..(sizeCtx-1)]
)
return $ Ctx b
poke_hashlen :: Ptr Ctx -> IO Int
poke_hashlen ptr = do
a <- peek (ptr `plusPtr` 3)
b <- peek (ptr `plusPtr` 2)
c <- peek (ptr `plusPtr` 1)
d <- peek (ptr `plusPtr` 0)
return (sl a 24 .|. sl b 16 .|. sl c 8 .|. sl d 0)
where
sl :: Word8 -> Int -> Int
sl a r = (fromIntegral a) `shiftL` r
foreign import ccall unsafe "skein256.h skein256_init"
c_skein256_init :: Ptr Ctx -> CUInt -> IO ()
foreign import ccall "skein256.h skein256_update"
c_skein256_update :: Ptr Ctx -> CString -> Word32 -> IO ()
foreign import ccall unsafe "skein256.h skein256_finalize"
c_skein256_finalize :: Ptr Ctx -> CString -> IO ()
allocInternal :: (Ptr Ctx -> IO a) -> IO a
allocInternal = alloca
allocInternalFrom :: Ctx -> (Ptr Ctx -> IO a) -> IO a
allocInternalFrom ctx f = allocInternal $ \ptr -> (poke ptr ctx >> f ptr)
updateInternalIO :: Ptr Ctx -> ByteString -> IO ()
updateInternalIO ptr d =
unsafeUseAsCStringLen d (\(cs, len) -> c_skein256_update ptr cs (fromIntegral len))
finalizeInternalIO :: Ptr Ctx -> IO ByteString
finalizeInternalIO ptr = do
digestSize <- fmap (\x -> (x + 7) `shiftR` 3) $ poke_hashlen ptr
allocaBytes digestSize (\cs -> c_skein256_finalize ptr cs >> B.packCStringLen (cs, digestSize))
{-# NOINLINE init #-}
-- | init a context
init :: Int -> Ctx
init hashlen = unsafePerformIO $ allocInternal $ \ptr -> do (c_skein256_init ptr (fromIntegral hashlen) >> peek ptr)
{-# NOINLINE update #-}
-- | update a context with a bytestring
update :: Ctx -> ByteString -> Ctx
update ctx d = unsafePerformIO $ allocInternalFrom ctx $ \ptr -> do updateInternalIO ptr d >> peek ptr
{-# NOINLINE finalize #-}
-- | finalize the context into a digest bytestring
finalize :: Ctx -> ByteString
finalize ctx = unsafePerformIO $ allocInternalFrom ctx $ \ptr -> do finalizeInternalIO ptr
{-# NOINLINE hash #-}
-- | hash a strict bytestring into a digest bytestring
hash :: Int -> ByteString -> ByteString
hash hashlen d = unsafePerformIO $ allocInternal $ \ptr -> do
c_skein256_init ptr (fromIntegral hashlen) >> updateInternalIO ptr d >> finalizeInternalIO ptr
{-# NOINLINE hashlazy #-}
-- | hash a lazy bytestring into a digest bytestring
hashlazy :: Int -> L.ByteString -> ByteString
hashlazy hashlen l = unsafePerformIO $ allocInternal $ \ptr -> do
c_skein256_init ptr (fromIntegral hashlen) >> mapM_ (updateInternalIO ptr) (L.toChunks l) >> finalizeInternalIO ptr