module Crypto.Cipher.Types.GF
(
xtsGFMul
) where
import Crypto.Internal.Imports
import Crypto.Internal.ByteArray (ByteArray, withByteArray)
import qualified Crypto.Internal.ByteArray as B
import Foreign.Storable
import Foreign.Ptr
import Data.Bits
xtsGFMul :: ByteArray ba => ba -> ba
xtsGFMul :: ba -> ba
xtsGFMul b :: ba
b
| Int
len Int -> Int -> Bool
forall a. Eq a => a -> a -> Bool
== 16 =
Int -> (Ptr Any -> IO ()) -> ba
forall a p. ByteArray a => Int -> (Ptr p -> IO ()) -> a
B.allocAndFreeze Int
len ((Ptr Any -> IO ()) -> ba) -> (Ptr Any -> IO ()) -> ba
forall a b. (a -> b) -> a -> b
$ \dst :: Ptr Any
dst ->
ba -> (Ptr Any -> IO ()) -> IO ()
forall ba p a. ByteArrayAccess ba => ba -> (Ptr p -> IO a) -> IO a
withByteArray ba
b ((Ptr Any -> IO ()) -> IO ()) -> (Ptr Any -> IO ()) -> IO ()
forall a b. (a -> b) -> a -> b
$ \src :: Ptr Any
src -> do
(hi :: Word64
hi,lo :: Word64
lo) <- Word64 -> Word64 -> (Word64, Word64)
gf (Word64 -> Word64 -> (Word64, Word64))
-> IO Word64 -> IO (Word64 -> (Word64, Word64))
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Ptr Word64 -> IO Word64
forall a. Storable a => Ptr a -> IO a
peek (Ptr Any -> Ptr Word64
forall a b. Ptr a -> Ptr b
castPtr Ptr Any
src) IO (Word64 -> (Word64, Word64)) -> IO Word64 -> IO (Word64, Word64)
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> Ptr Word64 -> IO Word64
forall a. Storable a => Ptr a -> IO a
peek (Ptr Any -> Ptr Any
forall a b. Ptr a -> Ptr b
castPtr Ptr Any
src Ptr Any -> Int -> Ptr Word64
forall a b. Ptr a -> Int -> Ptr b
`plusPtr` 8)
Ptr Word64 -> Word64 -> IO ()
forall a. Storable a => Ptr a -> a -> IO ()
poke (Ptr Any -> Ptr Word64
forall a b. Ptr a -> Ptr b
castPtr Ptr Any
dst) Word64
lo
Ptr Word64 -> Word64 -> IO ()
forall a. Storable a => Ptr a -> a -> IO ()
poke (Ptr Any -> Ptr Any
forall a b. Ptr a -> Ptr b
castPtr Ptr Any
dst Ptr Any -> Int -> Ptr Word64
forall a b. Ptr a -> Int -> Ptr b
`plusPtr` 8) Word64
hi
| Bool
otherwise = [Char] -> ba
forall a. HasCallStack => [Char] -> a
error "unsupported block size in GF"
where gf :: Word64 -> Word64 -> (Word64, Word64)
gf :: Word64 -> Word64 -> (Word64, Word64)
gf srcLo :: Word64
srcLo srcHi :: Word64
srcHi =
((if Bool
carryLo then (Word64 -> Word64 -> Word64
forall a. Bits a => a -> a -> a
.|. 1) else Word64 -> Word64
forall a. a -> a
id) (Word64
srcHi Word64 -> Int -> Word64
forall a. Bits a => a -> Int -> a
`shiftL` 1)
,(if Bool
carryHi then Word64 -> Word64 -> Word64
forall a. Bits a => a -> a -> a
xor 0x87 else Word64 -> Word64
forall a. a -> a
id) (Word64 -> Word64) -> Word64 -> Word64
forall a b. (a -> b) -> a -> b
$ (Word64
srcLo Word64 -> Int -> Word64
forall a. Bits a => a -> Int -> a
`shiftL` 1)
)
where carryHi :: Bool
carryHi = Word64
srcHi Word64 -> Int -> Bool
forall a. Bits a => a -> Int -> Bool
`testBit` 63
carryLo :: Bool
carryLo = Word64
srcLo Word64 -> Int -> Bool
forall a. Bits a => a -> Int -> Bool
`testBit` 63
len :: Int
len = ba -> Int
forall ba. ByteArrayAccess ba => ba -> Int
B.length ba
b