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-- |
-- Module : Crypto.Random
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : Good
--
-- Provide a safe abstraction for cryptographic pseudo
-- random generator.
--
{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE DeriveDataTypeable #-}
module Crypto.Random
(
-- * Entropy
EntropyPool
, createEntropyPool
, grabEntropy
, grabEntropyIO
-- * Random generation
, CPRG(..)
, withRandomBytes
-- * System generator
, SystemRNG
-- * Testing and mocking
, createTestEntropyPool
) where
import Crypto.Random.Entropy
import Crypto.Random.Generator
import Data.ByteString (ByteString)
import Data.Typeable (Typeable)
import qualified Data.ByteString.Internal as B (unsafeCreate)
-- | System entropy generator.
--
-- This generator doesn't use the entropy reseed level, as the only bytes
-- generated are comping from the entropy pool already.
--
-- This generator doesn't create reproducible output, and might be difficult to
-- use for testing and debugging purpose, but otherwise for real world use case
-- should be fine.
data SystemRNG = SystemRNG EntropyPool
deriving Typeable
instance CPRG SystemRNG where
cprgCreate entPool = SystemRNG entPool
cprgSetReseedThreshold _ r = r
cprgFork r@(SystemRNG entPool) = (r, cprgCreate entPool)
cprgGenerate n g@(SystemRNG entPool) = (B.unsafeCreate n (grabEntropyPtr n entPool), g)
-- we don't need to do anything different when generating withEntropy, as the generated
-- bytes are already stricly entropy bytes.
cprgGenerateWithEntropy n g = cprgGenerate n g
-- | generate @len random bytes and mapped the bytes to the function @f.
--
-- This is equivalent to use Control.Arrow 'first' with 'cprgGenerate'
withRandomBytes :: CPRG g => g -> Int -> (ByteString -> a) -> (a, g)
withRandomBytes rng len f = (f bs, rng')
where (bs, rng') = cprgGenerate len rng
|
