45 lines
1.2 KiB
Haskell
45 lines
1.2 KiB
Haskell
-- |
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-- Module : Crypto.PubKey.Internal
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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.PubKey.Internal
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( and'
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, (&&!)
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, dsaTruncHash
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, dsaTruncHashDigest
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) where
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import Data.Bits (shiftR)
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import Data.List (foldl')
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import Crypto.Hash
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import Crypto.Internal.ByteArray (ByteArrayAccess)
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import Crypto.Number.Basic (numBits)
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import Crypto.Number.Serialize
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-- | This is a strict version of and
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and' :: [Bool] -> Bool
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and' l = foldl' (&&!) True l
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-- | This is a strict version of &&.
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(&&!) :: Bool -> Bool -> Bool
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True &&! True = True
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True &&! False = False
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False &&! True = False
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False &&! False = False
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-- | Truncate and hash for DSA and ECDSA.
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dsaTruncHash :: (ByteArrayAccess msg, HashAlgorithm hash) => hash -> msg -> Integer -> Integer
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dsaTruncHash hashAlg = dsaTruncHashDigest hashAlg . hashWith hashAlg
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-- | Truncate a digest for DSA and ECDSA.
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dsaTruncHashDigest :: HashAlgorithm hash => hash -> Digest hash -> Integer -> Integer
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dsaTruncHashDigest hashAlg digest n
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| d > 0 = shiftR e d
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| otherwise = e
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where e = os2ip digest
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d = hashDigestSize hashAlg * 8 - numBits n
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