haskell/cryptonite
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Avoid repeated point encoding

Browse Source
This commit is contained in:
Olivier Chéron 2020-02-04 21:23:29 +01:00
parent 6075b698e1
commit 633879f801
1 changed files with 14 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
Crypto/PubKey/EdDSA.hs
View File

@ -148,9 +148,10 @@ sign prx priv pub msg =
digR = hashFinalize $ hashUpdate (hashUpdate (hashInitWithDom prx) prefix) msg
r = decodeScalarNoErr prx digR
pR = pointBaseSmul prx r
sK = getK prx pub pR msg
bsR = encodePoint prx pR
sK = getK prx pub bsR msg
sS = scalarAdd prx r (scalarMul prx sK s)
in encodeSignature prx (pR, sS)
in encodeSignature prx (bsR, pR, sS)
-- | Verify a message
verify :: (EllipticCurveEdDSA curve, ByteArrayAccess msg)
@ -161,37 +162,36 @@ verify prx pub msg sig =
CryptoFailed _ -> False
where
doVerify = do
(pR, sS) <- decodeSignature prx sig
(bsR, pR, sS) <- decodeSignature prx sig
nPub <- pointNegate prx `fmap` publicPoint prx pub
let sK = getK prx pub pR msg
let sK = getK prx pub bsR msg
pR' = pointsSmulVarTime prx sS sK nPub
return (pR == pR')
getK :: (EllipticCurveEdDSA curve, ByteArrayAccess msg)
=> proxy curve -> PublicKey curve -> Point curve -> msg -> Scalar curve
getK prx pub pR msg =
let bsR = encodePoint prx pR :: Bytes
digK = hashFinalize $ hashUpdate (hashUpdate (hashUpdate (hashInitWithDom prx) bsR) pub) msg
=> proxy curve -> PublicKey curve -> Bytes -> msg -> Scalar curve
getK prx pub bsR msg =
let digK = hashFinalize $ hashUpdate (hashUpdate (hashUpdate (hashInitWithDom prx) bsR) pub) msg
in decodeScalarNoErr prx digK
encodeSignature :: EllipticCurveEdDSA curve
=> proxy curve
-> (Point curve, Scalar curve)
-> (Bytes, Point curve, Scalar curve)
-> Signature curve
encodeSignature prx (pR, sS) =
encodeSignature prx (bsR, _, sS) =
let bsS = encodeScalarLE prx sS :: Bytes
len0 = signatureSize prx - publicKeySize prx - B.length bsS
in Signature $ B.concat [ encodePoint prx pR, bsS, B.zero len0 ]
len0 = signatureSize prx - B.length bsR - B.length bsS
in Signature $ B.concat [ bsR, bsS, B.zero len0 ]
decodeSignature :: EllipticCurveEdDSA curve
=> proxy curve
-> Signature curve
-> CryptoFailable (Point curve, Scalar curve)
-> CryptoFailable (Bytes, Point curve, Scalar curve)
decodeSignature prx (Signature bs) = do
let (bsR, bsS) = B.splitAt (publicKeySize prx) bs
pR <- decodePoint prx bsR
sS <- decodeScalarLE prx bsS
return (pR, sS)
return (bsR, pR, sS)
-- implementations are supposed to decode any scalar up to the size of the digest
decodeScalarNoErr :: (EllipticCurveEdDSA curve, ByteArrayAccess bs)