[Haskell-cafe] haskell crypto is reaaaaaaaaaally slow

[Donald Bruce Stewart]

> > aeyakovenko:
> > > $ time ./md5sum ./md5sum
> > > [105,252,52,138,187,192,216,17,225,123,185,3,124,101,86,132]
> > > 
> > > real    0m4.790s
> > > user    0m3.688s
> > > sys     0m0.492s
> > > 
> > > $ time md5sum ./md5sum
> > > 69fc348abbc0d811e17bb9037c655684  ./md5sum
> > > 
> > > real    0m0.023s
> > > user    0m0.000s
> > > sys     0m0.008s
> > > 

I wasn't happy with the hex printing loop. Here's a shorter version.


    {-# OPTIONS -O2 -fffi #-}
    --
    -- ghc MD5.hs -o hsmd5 -lcrypto
    --

    import System.Environment
    import qualified Data.ByteString.Base as B (unsafeUseAsCStringLen)
    import qualified Data.ByteString      as B
    import Foreign
    import Foreign.C.Types
    import Numeric
    import Text.Printf
    import Control.Monad

    main = do
        (f:_)  <- getArgs
        src    <- B.readFile f
        printf "MD5 (%s) = %s \n" f (md5sum src)

    -- Fast md5 using OpenSSL and non-copying bytestrings
    md5sum :: B.ByteString -> String
    md5sum p = unsafePerformIO $ B.unsafeUseAsCStringLen p $ \(ptr,n) -> do
        digest  <- c_md5 ptr (fromIntegral n) nullPtr
        liftM concat $ forM [0..15] $ \n -> do
                            w <- peekElemOff digest n
                            return $ case showHex w [] of [x] -> ['0', x]; x -> x

    -- unsigned char *MD5(const unsigned char *d, unsigned long n, unsigned char *md);
    foreign import ccall "openssl/md5.h MD5" c_md5
        :: Ptr CChar -> CULong -> Ptr CChar -> IO (Ptr Word8)


ByteStrings were designed for this zero-copy passing of big data to C,
by the way, so its a perfect fit.

-- Don