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|
{-|
Maintainer: Thomas.DuBuisson@gmail.com
Stability: beta
Portability: portable
Obtain entropy from system sources or x86 RDRAND when available.
-}
module System.EntropyGhcjs
( CryptHandle
, openHandle
, hGetEntropy
, closeHandle
, hardwareRandom
) where
import Data.ByteString as B
import GHCJS.DOM.Crypto as Crypto
import GHCJS.DOM.Types (ArrayBufferView (..), fromJSValUnchecked)
import GHCJS.DOM.GlobalCrypto (getCrypto)
import GHCJS.DOM (globalThisUnchecked)
import Language.Javascript.JSaddle.Object as JS
-- |Handle for manual resource management
newtype CryptHandle = CH Crypto
-- | Get random values from the hardware RNG or return Nothing if no
-- supported hardware RNG is available.
--
-- Not supported on ghcjs.
hardwareRandom :: Int -> IO (Maybe B.ByteString)
hardwareRandom _ = pure Nothing
-- |Open a `CryptHandle`
openHandle :: IO CryptHandle
openHandle = do
this <- globalThisUnchecked
CH <$> getCrypto this
-- |Close the `CryptHandle`
closeHandle :: CryptHandle -> IO ()
closeHandle _ = pure ()
-- |Read random data from a `CryptHandle`
hGetEntropy :: CryptHandle -> Int -> IO B.ByteString
hGetEntropy (CH h) n = do
arr <- JS.new (jsg "Int8Array") [n]
getRandomValues_ h (ArrayBufferView arr)
B.pack <$> fromJSValUnchecked arr
|
