[Haskell-cafe] Password hashing

[Thomas Hartman]

What does haskell cafe think of the following module for drop-in
password hasing for webapps? Seem reasonable?

import Data.Digest.SHA512 (hash)
import qualified Data.ByteString as B'
import qualified Data.ByteString.Char8 as B

-- store passwords as md5 hash, as a security measure
scramblepass :: String -> IO String
scramblepass p = do
  etSalt <- try $ readFile "secure/salt"
  case etSalt of
    Left e -> fail errmsg
    Right s -> -- return . show . md5 . L.pack $ p ++ s
               return . B.unpack . B'.pack . hash . B'.unpack . B.pack $ p ++ s
  where errmsg = "scramblepass error, you probably need to create a
salt file in secure/salt. This is used for \
            \hashing passwords, so keep it secure. chmod u=r
secure/salt, and make sure it's skipped \
            \in version control commits, etc. A good way to generate a
salt file is (e.g., on ubuntu) \
            \writeFile \"secure/salt\" =<< ( strongsalt $ readFile
\"/dev/urandom\")\
            \You could also just type some random seeming text into
this file, though that's not quite as secure.\
            \Keep a backup copy of this file somewhere safe in case of
disaster."


-- | eg, on ubuntu: strongsalt $ readFile "/dev/urandom"
strongsalt :: IO String -> IO String
strongsalt randomSource = return . salt' =<< randomSource
  where salt' = show . fst . next . mkStdGen . read . concat . map
(show . ord) . take 10



2008/10/30 Bulat Ziganshin <bulat.ziganshin at gmail.com>:
> Hello Thomas,
>
> Thursday, October 30, 2008, 3:32:46 PM, you wrote:
>
>> No salt, but apart from that, should be fine, right?
>
> 1) without salt, it's not serious - easily breaked by dictionary
> attack
>
> 2) afair, md5 isn't condidered now as cryptographic hash
>
>
>
> --
> Best regards,
>  Bulat                            mailto:Bulat.Ziganshin at gmail.com
>
>