How about the following?
The main doubts I'm having at this point concern the takerandom part.
Does this seem reasonable?
Also, someone in the thread mentioned that a calculation that took a
couple of seconds to complete was a good thing because it makes
dictionary cracking harder. But
makeSaltedPasswordLinux "meh"
is virtually instantaneous, so I guess I'm doing something wrong?
Thanks for advice!
thomas.
thartman@thartman-laptop:~/hackage/HAppSHelpers>cat HAppS/Helpers/Security.hs
-- | Password hashes are based on a salt from a source of randomness
(eg /dev/urandom), and
-- | the SHA512 hashing function
module HAppS.Helpers.Security (
makeSaltedPassword, makeSaltedPasswordLinux, checkpass
)
where
import qualified Data.ByteString.Char8 as B
import qualified Data.ByteString as B'
import Control.Monad.Error
import System.IO.Error
import Random
import Data.Digest.SHA512 (hash)
import Data.Char
data SaltedPassword = SaltedPassword HashedPass Salt
deriving Show
newtype Password = Password String
deriving Show
newtype Salt = Salt String
deriving Show
newtype HashedPass = HashedPass String
deriving (Eq, Show)
checkpass :: Password -> SaltedPassword -> Bool
checkpass passattempt ( SaltedPassword hashedPass salt ) =
let hashedPassAttempt = hashpass passattempt salt
in hashedPassAttempt == hashedPass
hashpass :: Password -> Salt -> HashedPass
hashpass (Password p) (Salt s) = HashedPass . B.unpack . B'.pack .
hash . B'.unpack . B.pack $ p ++ s
-- | This works at least on ubuntu hardy heron, I don't know how portable it is
-- > makeSaltedPasswordLinux p = getSaltedPassword $ readFile "/dev/urandom")
makeSaltedPasswordLinux :: Password -> IO SaltedPassword
makeSaltedPasswordLinux = makeSaltedPassword $ readFile "/dev/urandom"
makeSaltedPassword :: IO String -> Password -> IO SaltedPassword
makeSaltedPassword randomsource pass = do
etR <- try $ return . takerandom =<< randomsource
case etR of
Left e -> fail . show $ e
Right s -> do let salt = Salt s
hp = hashpass pass salt
return $ SaltedPassword hp salt
takerandom :: String -> String
takerandom = show . fst . next . mkStdGen . read . concat . map (show
. ord) . take 1000
2008/11/25 Bulat Ziganshin
Hello Thomas,
Tuesday, November 25, 2008, 6:39:27 PM, you wrote:
Just to note, the comment about md5 is incorrect. I switched to SHA512 as you can see in the code.
really? :)
Right s -> -- return . show . md5 . L.pack $ p ++ s
typical salt usage is generation of new salt for every encryption operation and storing together with encrypted data
-- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com