#!/usr/bin/runghc
-- These methods do CSPRNG
-- https://stackoverflow.com/questions/20889729/how-to-properly-generate-a-random-bytestring-in-haskell
-- https://tommd.github.io/posts/RNG-Bench.html
-- ghc-crypto-api (old), ghc-cryptonite (retired), ghc-crypton (current) have similar API
-- sudo dnf install ghc-crypton-* ghc-entropy*

import Crypto.Random (getRandomBytes)
import Data.ByteString (ByteString)
import System.Entropy

generateSecureRandomBytes :: Int -> IO ByteString
generateSecureRandomBytes n = getRandomBytes n

main :: IO ()
main = do
  -- With Crypton/Cryptonite/Crypto-api
  randomBytes <- generateSecureRandomBytes 16
  print randomBytes

  -- With System.Entropy
  randBytes <- getEntropy 16
  print randBytes