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sm9: sm9: use bigmod instead of math/big, verify method

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This commit is contained in:
Sun Yimin 2022-12-02 14:33:54 +08:00 committed by GitHub
parent acf6edec18
commit 9c8836b2c6
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 19 additions and 11 deletions
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30
sm9/sm9.go
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@ -121,7 +121,7 @@ func Sign(rand io.Reader, priv *SignPrivateKey, hash []byte) (h *big.Int, s *bn2
if err != nil {
return nil, nil, err
}
return parseSignature(sig)
return parseSignatureLegacy(sig)
}
// Sign signs digest with user's DSA key, reading randomness from rand. The opts argument
@ -171,9 +171,10 @@ func SignASN1(rand io.Reader, priv *SignPrivateKey, hash []byte) ([]byte, error)
// Verify verifies the signature in h, s of hash using the master dsa public key and user id, uid and hid.
// Its return value records whether the signature is valid. Please use VerifyASN1 instead.
func Verify(pub *SignMasterPublicKey, uid []byte, hid byte, hash []byte, h *big.Int, s *bn256.G1) bool {
hBytes := make([]byte, orderNat.Size())
h.FillBytes(hBytes)
sig, err := encodeSignature(hBytes, s)
if h.Sign() <= 0 {
return false
}
sig, err := encodeSignature(h.Bytes(), s)
if err != nil {
return false
}
@ -189,7 +190,7 @@ func encodeSignature(hBytes []byte, s *bn256.G1) ([]byte, error) {
return b.Bytes()
}
func parseSignature(sig []byte) (*big.Int, *bn256.G1, error) {
func parseSignature(sig []byte) ([]byte, *bn256.G1, error) {
var (
hBytes []byte
sBytes []byte
@ -203,7 +204,6 @@ func parseSignature(sig []byte) (*big.Int, *bn256.G1, error) {
!inner.Empty() {
return nil, nil, errors.New("invalid ASN.1")
}
h := new(big.Int).SetBytes(hBytes)
if sBytes[0] != 4 {
return nil, nil, errors.New("sm9: invalid point format")
}
@ -212,7 +212,15 @@ func parseSignature(sig []byte) (*big.Int, *bn256.G1, error) {
if err != nil {
return nil, nil, err
}
return h, s, nil
return hBytes, s, nil
}
func parseSignatureLegacy(sig []byte) (*big.Int, *bn256.G1, error) {
hBytes, s, err := parseSignature(sig)
if err != nil {
return nil, nil, err
}
return new(big.Int).SetBytes(hBytes), s, nil
}
// VerifyASN1 verifies the ASN.1 encoded signature of type SM9Signature, sig, of hash using the
@ -222,17 +230,17 @@ func VerifyASN1(pub *SignMasterPublicKey, uid []byte, hid byte, hash, sig []byte
if err != nil {
return false
}
if h.Sign() <= 0 || h.Cmp(bn256.Order) >= 0 {
return false
}
if !s.IsOnCurve() {
return false
}
hNat, err := bigmod.NewNat().SetBytes(h.Bytes(), orderNat)
hNat, err := bigmod.NewNat().SetBytes(h, orderNat)
if err != nil {
return false
}
if hNat.IsZero() == 1 {
return false
}
t, err := pub.ScalarBaseMult(hNat.Bytes(orderNat))
if err != nil {