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sm2: add comments and refactor

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Sun Yimin 2023-12-15 15:11:49 +08:00 committed by GitHub
parent cad90f95ec
commit 515aa31259
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 27 additions and 19 deletions
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22
sm2/sm2.go
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@ -620,7 +620,7 @@ func (priv *PrivateKey) inverseOfPrivateKeyPlus1(c *sm2Curve) (*bigmod.Nat, erro
}
func signSM2EC(c *sm2Curve, priv *PrivateKey, rand io.Reader, hash []byte) (sig []byte, err error) {
// get/compute inv(d+1)
// dp1Inv = (d+1)⁻¹
dp1Inv, err := priv.inverseOfPrivateKeyPlus1(c)
if err != nil {
return nil, err
@ -649,21 +649,27 @@ func signSM2EC(c *sm2Curve, priv *PrivateKey, rand io.Reader, hash []byte) (sig
if err != nil {
return nil, err
}
r.Add(e, c.N) // r = (Rx + e) mod N
// r = [Rx + e]
r.Add(e, c.N)
// checks if r is zero or [r+k] is zero
if r.IsZero() == 0 {
t := bigmod.NewNat().Set(k)
t.Add(r, c.N)
if t.IsZero() == 0 { // if (r + k) != N then ok
t := bigmod.NewNat().Set(k).Add(r, c.N)
if t.IsZero() == 0 {
break
}
}
}
// s = [r * d]
s, err = bigmod.NewNat().SetBytes(priv.D.Bytes(), c.N)
if err != nil {
return nil, err
}
s.Mul(r, c.N)
// k = [k - s]
k.Sub(s, c.N)
// k = [(d+1)⁻¹ * (k - r * d)]
k.Mul(dp1Inv, c.N)
if k.IsZero() == 0 {
break
@ -738,21 +744,25 @@ func verifySM2EC(c *sm2Curve, pub *ecdsa.PublicKey, hash, sig []byte) bool {
e := bigmod.NewNat()
hashToNat(c, e, hash)
// t = [r + s]
t := bigmod.NewNat().Set(r)
t.Add(s, c.N)
if t.IsZero() == 1 {
return false
}
// p₁ = [s]G
p1, err := c.newPoint().ScalarBaseMult(s.Bytes(c.N))
if err != nil {
return false
}
// p₂ = [t]Q
p2, err := Q.ScalarMult(Q, t.Bytes(c.N))
if err != nil {
return false
}
// BytesX returns an error for the point at infinity.
Rx, err := p1.Add(p1, p2).BytesX()
if err != nil {
return false
@ -762,8 +772,8 @@ func verifySM2EC(c *sm2Curve, pub *ecdsa.PublicKey, hash, sig []byte) bool {
if err != nil {
return false
}
v.Add(e, c.N)
return v.Equal(r) == 1
}

18
sm2/sm2_envelopedkey.go
View File

@ -9,7 +9,6 @@ import (
"errors"
"fmt"
"io"
"math/big"
"github.com/emmansun/gmsm/cipher"
"github.com/emmansun/gmsm/sm4"
@ -106,9 +105,9 @@ func ParseEnvelopedPrivateKey(priv *PrivateKey, enveloped []byte) (*PrivateKey,
}
// parse public key
x, y := elliptic.Unmarshal(P256(), pub.RightAlign())
if x == nil || y == nil {
return nil, errors.New("sm2: invald public key in enveloped data")
pubKey, err := NewPublicKey(pub.RightAlign())
if err != nil {
return nil, err
}
// decrypt symmetric cipher key
@ -127,12 +126,11 @@ func ParseEnvelopedPrivateKey(priv *PrivateKey, enveloped []byte) (*PrivateKey,
plaintext := make([]byte, len(bytes))
mode.CryptBlocks(plaintext, bytes)
// Do we need to check length in order to be compatible with some implementations with padding?
sm2Key := new(PrivateKey)
sm2Key.D = new(big.Int).SetBytes(plaintext)
sm2Key.Curve = P256()
sm2Key.X, sm2Key.Y = sm2Key.ScalarBaseMult(plaintext)
if sm2Key.X.Cmp(x) != 0 || sm2Key.Y.Cmp(y) != 0 {
sm2Key, err := NewPrivateKey(plaintext)
if err != nil {
return nil, err
}
if !sm2Key.PublicKey.Equal(pubKey) {
return nil, errors.New("sm2: mismatch key pair in enveloped data")
}