{-# LANGUAGE CPP, ForeignFunctionInterface #-}

-- |
-- Module:    Data.Digest.SHA256
-- Copyright: Zooko O'Whielacronx
-- License:   GPL
--
-- Stability: experimental

-- ByteString-based, zero-copying binding to Crypto++'s sha interface

-- thanks to Don Stewart <dons@galois.com>, Matthew Sackman
-- <matthew@wellquite.org>, Brian O'Sullivan, lispy, Adam Langley

module Bundled.SHA256 ( sha256 ) where

import Foreign
import Foreign.C.Types
import Numeric (showHex)
import Foreign.C.String ( withCString )
import Data.ByteString.Unsafe (unsafeUseAsCStringLen)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Internal as BSI

sha256 :: BS.ByteString -> BS.ByteString
sha256 p = unsafePerformIO $ do
             digest <- BSI.create 32 $ \digest ->
                       unsafeUseAsCStringLen p $ \(ptr,n) ->
                           c_sha256 ptr (fromIntegral n) digest
             return $! digest

-- void sha256sum(const unsigned char *d, size_t n, unsigned char *md);
--
foreign import ccall unsafe "sha2.h hashed_storage_sha256" c_sha256
    :: Ptr CChar -> CSize -> Ptr Word8 -> IO ()