Cryptography coursera class exercise #3.

Main.hs

{-# LANGUAGE UnicodeSyntax #-}

import Control.Applicative ((<$>))
import Data.Monoid (mempty, (<>))
import Text.Printf (printf)

import Crypto.Hash.SHA256 (hash)
import Data.ByteString (ByteString)
import qualified Data.ByteString as B

main ∷ IO ()
main = split 1024 <$> B.readFile "data/video1.mp4" >>= printAsHex . foldr (\x a → hash $ x <> a) mempty
 where
  printAsHex = putStrLn . concatMap (printf "%02x") . B.unpack


split ∷ Int → ByteString → [ByteString]
split n s
  | B.null (B.drop n s) = [s]
  | otherwise = xs : split n ys
 where
  (xs, ys) = B.splitAt n s

% runhaskell Main.hs
5b96aece304a1422224f9a41b228416028f9ba26b0d1058f400200f06a589949