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[number] correct tweak function to mask things properly

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This commit is contained in:
Vincent Hanquez 2015-05-23 17:09:07 +01:00
parent e14d9cafc9
commit 0e048b77c4
1 changed files with 12 additions and 14 deletions
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26
Crypto/Number/Generate.hs
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@ -49,20 +49,18 @@ generateParams bits genTopPolicy generateOdd
| otherwise = os2ip . tweak <$> getRandomBytes bytes | otherwise = os2ip . tweak <$> getRandomBytes bytes
where where
tweak :: ScrubbedBytes -> ScrubbedBytes tweak :: ScrubbedBytes -> ScrubbedBytes
tweak orig = tweak orig = B.copyAndFreeze orig $ \p0 -> do
case (genTopPolicy, generateOdd) of let p1 = p0 `plusPtr` 1
(Nothing , False) -> orig pEnd = p0 `plusPtr` (bytes - 1)
(Nothing , True ) -> B.copyAndFreeze orig $ \p -> (p `plusPtr` (bytes-1)) |= 0x1 case genTopPolicy of
(Just topPolicy, _ ) -> B.copyAndFreeze orig $ \p0 -> do Nothing -> return ()
let p1 = p0 `plusPtr` 1 Just SetHighest -> p0 |= (1 `shiftL` bit)
pEnd = p0 `plusPtr` (bytes - 1) Just SetTwoHighest
case topPolicy of | bit == 0 -> do p0 $= 0x1
SetHighest -> p0 |= (1 `shiftL` bit) p1 |= 0x80
SetTwoHighest | bit == 0 -> do p0 $= 0x1 | otherwise -> p0 |= (0x3 `shiftL` (bit - 1))
p1 |= 0x80 p0 &= (complement $ mask)
| otherwise -> p0 |= (0x3 `shiftL` (bit - 1)) when generateOdd (pEnd |= 0x1)
p0 &= (complement $ mask)
when generateOdd (pEnd |= 0x1)
($=) :: Ptr Word8 -> Word8 -> IO () ($=) :: Ptr Word8 -> Word8 -> IO ()
($=) p w = poke p w ($=) p w = poke p w