BSD-3-Clause licensed and maintained by Thomas DuBuisson
This version can be pinned in stack with:entropy-,2952

Module documentation for


This package allows Haskell users to easily acquire entropy for use in critical security applications by calling out to either windows crypto api, unix/linux’s getrandom and /dev/urandom. Hardware RNGs (currently RDRAND, patches welcome) are supported via the hardwareRNG function.

Quick Start

To simply get random bytes use getEntropy:

#!/usr/bin/env cabal
{- cabal:
    build-depends: base, entropy, bytestring
import qualified Data.ByteString as BS
import           System.Entropy

main :: IO ()
main = print . BS.unpack =<< getEntropy 16
-- Example output: [241,191,215,193,225,27,121,244,16,155,252,41,131,38,6,100]

Faster Randoms from Hardware

Most x86 systems include a hardware random number generator. These can be faster but require more trust in the platform:

import qualified Data.ByteString as B
import           System.Entropy

eitherRNG :: Int -> IO B.ByteString
eitherRNG sz = maybe (getEntropy sz) pure =<< getHardwareEntropy sz

main :: IO ()
main = print . B.unpack =<< eitherRNG 32

This package supports Windows, {li,u}nix, QNX, and has preliminary support for HaLVM.

Typically tested on Linux and OSX - testers are as welcome as patches.

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