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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
where
tweak :: ScrubbedBytes -> ScrubbedBytes
tweak orig =
case (genTopPolicy, generateOdd) of
(Nothing , False) -> orig
(Nothing , True ) -> B.copyAndFreeze orig $ \p -> (p `plusPtr` (bytes-1)) |= 0x1
(Just topPolicy, _ ) -> B.copyAndFreeze orig $ \p0 -> do
let p1 = p0 `plusPtr` 1
pEnd = p0 `plusPtr` (bytes - 1)
case topPolicy of
SetHighest -> p0 |= (1 `shiftL` bit)
SetTwoHighest | bit == 0 -> do p0 $= 0x1
p1 |= 0x80
| otherwise -> p0 |= (0x3 `shiftL` (bit - 1))
p0 &= (complement $ mask)
when generateOdd (pEnd |= 0x1)
tweak orig = B.copyAndFreeze orig $ \p0 -> do
let p1 = p0 `plusPtr` 1
pEnd = p0 `plusPtr` (bytes - 1)
case genTopPolicy of
Nothing -> return ()
Just SetHighest -> p0 |= (1 `shiftL` bit)
Just SetTwoHighest
| bit == 0 -> do p0 $= 0x1
p1 |= 0x80
| otherwise -> p0 |= (0x3 `shiftL` (bit - 1))
p0 &= (complement $ mask)
when generateOdd (pEnd |= 0x1)
($=) :: Ptr Word8 -> Word8 -> IO ()
($=) p w = poke p w