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sm2: key exchange refactoring

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Sun Yimin 2022-08-24 16:53:11 +08:00 committed by GitHub
parent 21a9793600
commit 8f5dcb842e
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 35 additions and 52 deletions
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87
sm2/sm2_keyexchange.go
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@ -28,45 +28,33 @@ type KeyExchange struct {
v *ecdsa.PublicKey // internal state which will be used when compute the key and signature, u/v
}
func destroyBigInt(n *big.Int) {
if n != nil {
n.SetInt64(0)
}
}
func destroyPublicKey(pub *ecdsa.PublicKey) {
if pub != nil {
destroyBigInt(pub.X)
destroyBigInt(pub.Y)
}
}
func destroyBytes(bytes []byte) {
for v := range bytes {
bytes[v] = 0
}
}
// Destroy clear all internal state and Ephemeral private/public keys.
func (ke *KeyExchange) Destroy() {
if ke.z != nil {
for v := range ke.z {
ke.z[v] = 0
}
}
if ke.peerZ != nil {
for v := range ke.peerZ {
ke.peerZ[v] = 0
}
}
if ke.r != nil {
ke.r.SetInt64(0)
}
if ke.secret != nil {
if ke.secret.X != nil {
ke.secret.X.SetInt64(0)
}
if ke.secret.Y != nil {
ke.secret.Y.SetInt64(0)
}
}
if ke.peerSecret != nil {
if ke.peerSecret.X != nil {
ke.peerSecret.X.SetInt64(0)
}
if ke.peerSecret.Y != nil {
ke.peerSecret.Y.SetInt64(0)
}
}
if ke.v != nil {
if ke.v.X != nil {
ke.v.X.SetInt64(0)
}
if ke.v.Y != nil {
ke.v.Y.SetInt64(0)
}
}
destroyBytes(ke.z)
destroyBytes(ke.peerZ)
destroyBigInt(ke.r)
destroyPublicKey(ke.secret)
destroyPublicKey(ke.peerSecret)
destroyPublicKey(ke.v)
}
// NewKeyExchange create one new KeyExchange object
@ -210,7 +198,9 @@ func (ke *KeyExchange) avf(x *big.Int) *big.Int {
return t
}
func (ke *KeyExchange) implicitSig() []byte {
// mqv implements SM2-MQV procedure
func (ke *KeyExchange) mqv() {
// implicitSig: (sPriv + avf(ePub) * ePriv) mod N
// Calculate x2`
t := ke.avf(ke.secret.X)
@ -218,16 +208,15 @@ func (ke *KeyExchange) implicitSig() []byte {
t.Mul(t, ke.r)
t.Add(t, ke.privateKey.D)
t.Mod(t, ke.privateKey.Params().N)
return t.Bytes()
}
func (ke *KeyExchange) basePoint() (*big.Int, *big.Int) {
// new base point: peerPub + [x1](peerSecret)
// x1` = 2^w + (x & (2^w – 1))
x1 := ke.avf(ke.peerSecret.X)
// Point(x3, y3) = peerPub + [x1](peerSecret)
// Point(x, y) = peerPub + [x1](peerSecret)
x, y := ke.privateKey.ScalarMult(ke.peerSecret.X, ke.peerSecret.Y, x1.Bytes())
x, y = ke.privateKey.Add(ke.peerPub.X, ke.peerPub.Y, x, y)
return x, y
ke.v.X, ke.v.Y = ke.privateKey.ScalarMult(x, y, t.Bytes())
}
func respondKeyExchange(ke *KeyExchange, r *big.Int) (*ecdsa.PublicKey, []byte, error) {
@ -235,11 +224,7 @@ func respondKeyExchange(ke *KeyExchange, r *big.Int) (*ecdsa.PublicKey, []byte,
ke.secret.X, ke.secret.Y = ke.privateKey.ScalarBaseMult(r.Bytes())
ke.r = r
// Point(x3, y3) = peerPub + [x1](peerSecret)
x, y := ke.basePoint()
// V = [h*tB](Point(x3, y3))
ke.v.X, ke.v.Y = ke.privateKey.ScalarMult(x, y, ke.implicitSig())
ke.mqv()
if ke.v.X.Sign() == 0 && ke.v.Y.Sign() == 0 {
return nil, nil, errors.New("sm2: key exchange failed, V is infinity point")
}
@ -285,13 +270,11 @@ func (ke *KeyExchange) ConfirmResponder(rB *ecdsa.PublicKey, sB []byte) ([]byte,
}
ke.peerSecret = rB
x, y := ke.basePoint()
// U = [h*tA](Point(x3, y3))
ke.v.X, ke.v.Y = ke.privateKey.ScalarMult(x, y, ke.implicitSig())
ke.mqv()
if ke.v.X.Sign() == 0 && ke.v.Y.Sign() == 0 {
return nil, nil, errors.New("sm2: key exchange failed, U is infinity point")
}
if len(sB) > 0 {
buffer := ke.sign(false, 0x02)
if subtle.ConstantTimeCompare(buffer, sB) != 1 {