Basic Crypto Math (Haskell)

cryptoMath.hs

--file: cryptoMath.hs

-- Cryptopals: http://cryptopals.com/sets/1

-- Hex encoding: [0..9][A..F]
-- B64 encoding: [A..Z][a..z][0..9][+][/][[=]]

-- Note: Each hex char is 4 bits; each b64 char is 6 bits

module CryptoMath where
  import Numeric
  import Data.Digits
  import Data.Bits

  type BaseMap = [(Char, Integer)]

  b64IntMap :: BaseMap
  b64IntMap = zip (['A'..'Z']++['a'..'z']++['0'..'9']++['+','/']) [0..63]

  hexIntMap :: BaseMap
  hexIntMap = zip (['0'..'9']++['a'..'f']) [0..15]

  int2char :: Integer -> BaseMap -> Char
  int2char _ [] = '?'
  int2char n ((char, int):restMap) =
        if int == n then char else int2char n restMap

  hexStringToVal :: String -> Integer
  hexStringToVal s = fst $ head $ readHex s

  valToB64 :: Integer -> [Integer]
  valToB64 v = digits 64 v

  valToHex :: Integer -> [Integer]
  valToHex v = digits 16 v

  b64ToS :: [Integer] -> String
  b64ToS [] = []
  b64ToS (x:xs) = (int2char x b64IntMap) : b64ToS xs

  hexToS :: [Integer] -> String
  hexToS [] = []
  hexToS (x:xs) = (int2char x hexIntMap) : hexToS xs

  hexTo64 :: String -> String
  hexTo64 s = b64ToS $ valToB64 $ hexStringToVal s

  heXOR :: String -> String -> String
  heXOR x y= hexToS $ valToHex $ (hexStringToVal x) `xor` (hexStringToVal y)