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[number] remove the ByteString from generation of high bits

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Vincent Hanquez 2015-05-21 14:48:26 +01:00
parent 7f11a66d50
commit 16839d3a43
1 changed files with 7 additions and 4 deletions
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Crypto/Number/Generate.hs
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@ -16,9 +16,9 @@ import Crypto.Internal.Imports
import Crypto.Number.Basic import Crypto.Number.Basic
import Crypto.Number.Serialize import Crypto.Number.Serialize
import Crypto.Random.Types import Crypto.Random.Types
import qualified Data.ByteString as B
import Crypto.Internal.ByteArray (Bytes)
import Data.Bits ((.|.), (.&.), shiftR) import Data.Bits ((.|.), (.&.), shiftR)
import Crypto.Internal.ByteArray (Bytes, ScrubbedBytes)
import qualified Crypto.Internal.ByteArray as B
-- | generate a positive integer x, s.t. 0 <= x < m -- | generate a positive integer x, s.t. 0 <= x < m
@ -47,9 +47,12 @@ generateBetween low high = (low +) <$> generateMax (high - low + 1)
-- the number of bits need to be multiple of 8. It will always returns -- the number of bits need to be multiple of 8. It will always returns
-- an integer that is close to 2^(1+bits/8) by setting the 2 highest bits to 1. -- an integer that is close to 2^(1+bits/8) by setting the 2 highest bits to 1.
generateOfSize :: MonadRandom m => Int -> m Integer generateOfSize :: MonadRandom m => Int -> m Integer
generateOfSize bits = unmarshall <$> getRandomBytes (bits `div` 8) generateOfSize bits = os2ip . setHighest <$> getRandomBytes (bits `div` 8)
where where
unmarshall bs = os2ip $ snd $ B.mapAccumL (\acc w -> (0, w .|. acc)) 0xc0 bs setHighest :: ScrubbedBytes -> ScrubbedBytes
setHighest ran = case B.unpack ran of
[] -> B.empty
(w:ws) -> B.pack ((w .|. 0xc0) : ws)
-- | Generate a number with the specified number of bits -- | Generate a number with the specified number of bits
generateBits :: MonadRandom m => Int -> m Integer generateBits :: MonadRandom m => Int -> m Integer