--
-- Haskell version of MD5 example from the C# blog entry:
--   http://blogs.msdn.com/csharpfaq/archive/2006/10/09/How-do-I-calculate-a-MD5-hash-from-a-string_3F00_.aspx
-- 
module MD5 where

import NET
import Data.Word
import Numeric

calcMD5FromString :: String -> IO String
calcMD5FromString str = do
   md  <- invokeStatic "System.Security.Cryptography.MD5" "Create" ()
   fi  <- getFieldStatic "System.Text.Encoding" "ASCII" ()
   bs  <- fi  # invoke "GetBytes" str
   vec <- md  # invoke "ComputeHash" (bs :: Vector Word8)
   res <- vec # bytesToString
   let resStr = foldr (showHex) "" res
   return resStr

bytesToString :: Vector Word8 -> IO [Word8]
bytesToString vec = do
   len  <- vec # getField "Length" ()
   mapM (\ i -> do
           x <- vec # invoke "GetValue" (i::Int)
	   return (x::Word8))
        [0..((len::Int)-1)]