sourcecode: 
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module Crypto.Hash
( getHash, getHashWith, randomString )
where
import System.IO ( hClose, hGetLine, hPutStrLn )
import System.IOExts ( execCmd )
import System.Random ( getRandomSeed, nextInt )
--------------------------------------------------------------------------
-- Operations for hashing.
--- Default hashing function.
--- @param toHash - string which should be hashed
--- @return the hashSum of this str
getHash :: String -> IO String
getHash = getHashWith "md5sum"
--getHash = getHashWith "sha1sum"
--- Hashes a string with an explicit Unix hash command.
--- @param hashcmd - Unix command for hasing
--- @param toHash - string which should be hashed
--- @return the hashed string
getHashWith :: String -> String -> IO String
getHashWith hashcmd toHash = do
(sin, sout, _) <- execCmd hashcmd
hPutStrLn sin toHash
hClose sin
result <- hGetLine sout
return (head (words result))
--- Returns a random string (a hexadecimal string) of a particular length.
--- @param length - length of the desired string
--- @return the random string
randomString :: Int -> IO String
randomString n = do
seed <- getRandomSeed
ranString <- getHash (show (nextInt seed !! 3))
return (take n ranString)
--------------------------------------------------------------------------
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