MCLWasm.hs

-- | 
-- MCL WASM (https://github.com/herumi/mcl-wasm) serialisation support
-- MCL WASM uses the following algorithm to serialise
--   P = (x, y) in G1
--   if P.isZero() then 64-bytes zero.
--   otherwise,
--   d = x.serialize()
--   if (y.isOdd()) d[MSB] |= 0x80
-- On analysis of the GT format, each element of GT is simply LSB serialised 
-- and appended as a continuous bytestring, using the element length to split 
-- each point

module Pairing.Serialize.MCLWasm where
--   ( MCLWASM(..)
--   ) where
-- 
-- import Protolude hiding (putByteString)
-- import Pairing.Serialize.Types
-- import Pairing.Point
-- import Pairing.ByteRepr
-- import Pairing.CyclicGroup
-- import Data.Binary.Put (Put, putWord8, putWord16le, runPut, putByteString)
-- import Data.ByteString.Builder
-- import Data.ByteString as B hiding (length)
-- import qualified Data.ByteString as B
-- 
-- data MCLWASM = MCLWASM deriving (Eq, Show)
-- 
-- instance MkCompressedForm MCLWASM where
--   serializeCompressed _ = toCompressedForm
-- 
-- instance FromSerialisedForm MCLWASM where
--   unserializePoint _ = fromCompressedForm
-- 
-- toCompressedForm :: (ByteRepr a, FromX a) => Point a -> Maybe LByteString
-- toCompressedForm (Point x y) = do
--   ny <- yFromX x (\y1 y2 -> if isOdd y1 then y1 else y2)
--   rx <- mkRepr (ByteOrderLength LeastSignificantFirst minReprLength) x
--   bs <- if isOdd y then do
--         k <- toPaddedBytes (ByteOrderLength MostSignificantFirst (calcReprLength x minReprLength)) 0x80
--         pure (B.pack $ B.zipWith (.|.)  rx k)
--       else 
--         pure rx
--   pure (runPut $ putByteString bs)
-- toCompressedForm Infinity = Just (toLazyByteString (word8 0))
-- 
-- fromCompressedForm :: (ByteRepr a, FromX a) => Point a -> LByteString -> Either Text (Point a)
-- fromCompressedForm (Point onex _) bs = if isInfinity then pure Infinity else do
--   k <- note "Padding failed" (toPaddedBytes (ByteOrderLength MostSignificantFirst (calcReprLength onex minReprLength)) 0x80)
--   let 
--     nbs = B.pack $ B.zipWith (.&.) (toS bs) k
--     (xbs, yodd) = if fromBytesToInteger MostSignificantFirst nbs == 0x80 then
--         (B.pack (B.zipWith xor (toS bs) k), True)
--       else
--         (toS bs, False)
--   x <- note "Failed to deserialise x" (fromRepr (ByteOrderLength LeastSignificantFirst minReprLength) onex xbs)
--   y <- note "Failed to get y from x"  (yFromX x (selOdd yodd))
--   pure (Point x y)
--   where
--     selOdd yesOdd y1 y2 = if yesOdd then whichOdd y1 y2 else whichEven y1 y2 
--     whichOdd y1 y2 = if isOdd y1 then y1 else y2
--     whichEven y1 y2 = if isOdd y1 then y2 else y1
--     isInfinity = fromBytesToInteger MostSignificantFirst (toS bs) == 0
-- fromCompressedForm Infinity _ = Left "Cannot use infinity to extract from bytestring"