57 lines
1.6 KiB
Haskell
57 lines
1.6 KiB
Haskell
-- |
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-- Module : Crypto.Random.Entropy.Backend
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : stable
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-- Portability : good
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--
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{-# LANGUAGE CPP #-}
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{-# LANGUAGE ExistentialQuantification #-}
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module Crypto.Random.Entropy.Backend
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( EntropyBackend
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, supportedBackends
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, gatherBackend
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) where
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import Foreign.Ptr
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import Data.Word (Word8)
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import Crypto.Random.Entropy.Source
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#ifdef SUPPORT_RDRAND
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import Crypto.Random.Entropy.RDRand
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#endif
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#ifdef WINDOWS
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import Crypto.Random.Entropy.Windows
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#else
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import Crypto.Random.Entropy.Unix
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#endif
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-- | All supported backends
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supportedBackends :: [IO (Maybe EntropyBackend)]
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supportedBackends =
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[
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#ifdef SUPPORT_RDRAND
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openBackend (undefined :: RDRand),
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#endif
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#ifdef WINDOWS
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openBackend (undefined :: WinCryptoAPI)
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#else
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openBackend (undefined :: DevRandom), openBackend (undefined :: DevURandom)
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#endif
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]
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-- | Any Entropy Backend
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data EntropyBackend = forall b . EntropySource b => EntropyBackend b
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-- | Open a backend handle
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openBackend :: EntropySource b => b -> IO (Maybe EntropyBackend)
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openBackend b = fmap EntropyBackend `fmap` callOpen b
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where callOpen :: EntropySource b => b -> IO (Maybe b)
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callOpen _ = entropyOpen
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-- | Gather randomness from an open handle
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gatherBackend :: EntropyBackend -- ^ An open Entropy Backend
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-> Ptr Word8 -- ^ Pointer to a buffer to write to
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-> Int -- ^ number of bytes to write
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-> IO Int -- ^ return the number of bytes actually written
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gatherBackend (EntropyBackend backend) ptr n = entropyGather backend ptr n
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