73 lines
2.2 KiB
Haskell
73 lines
2.2 KiB
Haskell
-- |
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-- Module : Crypto.Internal.Bytes
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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 : unknown
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--
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-- internal helpers function to manipulate sequence of bytes
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-- like ByteString and buffer.
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--
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module Crypto.Internal.Bytes
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( withByteStringPtr
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, tempBufCreate
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, bufXor
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, bufXorWith
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, bufCopy
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, bufSet
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) where
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import Crypto.Internal.Imports
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import Foreign.Ptr (Ptr, plusPtr)
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import Foreign.ForeignPtr (withForeignPtr)
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import Foreign.Storable (peek, poke, pokeByteOff, peekByteOff)
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import Foreign.Marshal.Alloc (allocaBytesAligned)
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import Data.ByteString (ByteString)
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import Data.Bits (xor)
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import Data.ByteString.Internal (toForeignPtr)
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import Data.ByteString.Internal (memcpy, memset)
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withByteStringPtr :: ByteString -> (Ptr Word8 -> IO a) -> IO a
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withByteStringPtr b f =
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withForeignPtr fptr $ \ptr -> f (ptr `plusPtr` off)
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where (fptr, off, _) = toForeignPtr b
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-- | Create a new temporary buffer
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tempBufCreate :: Int -> (Ptr Word8 -> IO a) -> IO a
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tempBufCreate size f = allocaBytesAligned size 8 f
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-- | xor bytes from source1 and source2 to destination
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--
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-- d = s1 xor s2
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--
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-- s1, nor s2 are modified unless d point to s1 or s2
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bufXor :: Ptr Word8 -> Ptr Word8 -> Ptr Word8 -> Int -> IO ()
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bufXor _ _ _ 0 = return ()
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bufXor d s1 s2 n = do
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(xor <$> peek s1 <*> peek s2) >>= poke d
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bufXor (d `plusPtr` 1) (s1 `plusPtr` 1) (s2 `plusPtr` 1) (n-1)
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-- | xor bytes from source with a specific value to destination
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--
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-- d = replicate (sizeof s) v `xor` s
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bufXorWith :: Ptr Word8 -> Word8 -> Ptr Word8 -> Int -> IO ()
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bufXorWith d v s n = loop 0
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where
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loop i
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| i == n = return ()
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| otherwise = do
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(xor v <$> peekByteOff s i) >>= pokeByteOff d i
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loop (i+1)
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bufCopy :: Ptr Word8 -> Ptr Word8 -> Int -> IO ()
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bufCopy dst src n = memcpy dst src (fromIntegral n)
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-- | Set @n number of bytes to the same value @v
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bufSet :: Ptr Word8 -> Word8 -> Int -> IO ()
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bufSet start v n = memset start v (fromIntegral n) >>= \_ -> return ()
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{-loop 0
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where loop i
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| i == n = return ()
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| otherwise = pokeByteOff start i v >> loop (i+1)
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-}
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