35 lines
1.3 KiB
Haskell
35 lines
1.3 KiB
Haskell
-- |
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-- Module : Crypto.Random.Entropy.Unsafe
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : experimental
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-- Portability : Good
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--
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module Crypto.Random.Entropy.Unsafe
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( replenish
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, module Crypto.Random.Entropy.Backend
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) where
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import Data.Word (Word8)
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import Foreign.Ptr (Ptr, plusPtr)
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import Crypto.Random.Entropy.Backend
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-- | Refill the entropy in a buffer
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--
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-- call each entropy backend in turn until the buffer has
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-- been replenish.
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--
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-- If the buffer cannot be refill after 3 loopings, this will raise
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-- an User Error exception
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replenish :: Int -> [EntropyBackend] -> Ptr Word8 -> IO ()
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replenish _ [] _ = fail "cryptonite: random: cannot get any source of entropy on this system"
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replenish poolSize backends ptr = loop 0 backends ptr poolSize
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where loop :: Int -> [EntropyBackend] -> Ptr Word8 -> Int -> IO ()
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loop retry [] p n | n == 0 = return ()
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| retry == 3 = error "cryptonite: random: cannot fully replenish"
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| otherwise = loop (retry+1) backends p n
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loop _ (_:_) _ 0 = return ()
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loop retry (b:bs) p n = do
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r <- gatherBackend b p n
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loop retry bs (p `plusPtr` r) (n - r)
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