68 lines
2.7 KiB
Haskell
68 lines
2.7 KiB
Haskell
-- |
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-- Module : Crypto.KDF.Scrypt
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : experimental
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-- Portability : unknown
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--
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-- Scrypt key derivation function as defined in Colin Percival's paper "Stronger Key Derivation via Sequential Memory-Hard Functions" <http://www.tarsnap.com/scrypt/scrypt.pdf>.
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--
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{-# LANGUAGE BangPatterns #-}
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{-# LANGUAGE ForeignFunctionInterface #-}
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{-# LANGUAGE CPP #-}
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module Crypto.KDF.Scrypt
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( Parameters(..)
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, generate
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) where
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import Data.Word
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import Data.Byteable
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import Data.ByteString (ByteString)
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import qualified Data.ByteString as B
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import qualified Data.ByteString.Internal as B
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import Foreign.Marshal.Alloc
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import Foreign.Ptr (Ptr, plusPtr)
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import Foreign.ForeignPtr (withForeignPtr)
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import Control.Monad (forM_)
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import System.IO.Unsafe
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import Crypto.Hash (SHA256(..))
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import qualified Crypto.KDF.PBKDF2 as PBKDF2
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import Crypto.Internal.Compat (popCount)
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-- | Parameters for Scrypt
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data Parameters = Parameters
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{ password :: ByteString -- ^ Password (bytes encoded)
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, salt :: ByteString -- ^ Salt (bytes encoded)
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, n :: Word64 -- ^ Cpu/Memory cost ratio. must be a power of 2 greater than 1. also known as N.
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, r :: Int -- ^ Must satisfy r * p < 2^30
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, p :: Int -- ^ Must satisfy r * p < 2^30
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, outputLength :: Int -- ^ the number of bytes to generate out of Scrypt
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}
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foreign import ccall "cryptonite_scrypt_smix"
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ccryptonite_scrypt_smix :: Ptr Word8 -> Word32 -> Word64 -> Ptr Word8 -> Ptr Word8 -> IO ()
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-- | Generate the scrypt key derivation data
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generate :: Parameters -> B.ByteString
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generate params
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| r params * p params >= 0x40000000 =
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error "Scrypt: invalid parameters: r and p constraint"
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| popCount (n params) /= 1 =
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error "Scrypt: invalid parameters: n not a power of 2"
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| otherwise = unsafePerformIO $ do
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let b = PBKDF2.generate prf (PBKDF2.Parameters (password params) (salt params) 1 intLen)
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fptr <- B.mallocByteString intLen
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allocaBytesAligned (128*(fromIntegral $ n params)*(r params)) 8 $ \v ->
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allocaBytesAligned (256*r params) 8 $ \xy ->
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withForeignPtr fptr $ \bPtr -> do
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withBytePtr b $ \bOrig -> B.memcpy bPtr bOrig (fromIntegral intLen)
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forM_ [0..(p params-1)] $ \i ->
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ccryptonite_scrypt_smix (bPtr `plusPtr` (i * 128 * (r params)))
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(fromIntegral $ r params) (n params) v xy
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return $ PBKDF2.generate prf (PBKDF2.Parameters (password params) (B.PS fptr 0 intLen) 1 (outputLength params))
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where prf = PBKDF2.prfHMAC SHA256
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intLen = p params * 128 * r params
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