add checks in sm2 encryption

sm2/encryption.go

@@ -137,6 +137,9 @@ func Encrypt(pub *ecdsa.PublicKey, data []byte) ([]byte, error) {
 		copy(encryptData[32-len(x1.Bytes()):], x1.Bytes())
 		copy(encryptData[64-len(y1.Bytes()):], y1.Bytes())
 
+		if pub.X.Sign() == 0 && pub.Y.Sign() == 0 {
+			return nil, errors.New("invalid public key")
+		}
 		x2, y2 = c.ScalarMult(pub.X, pub.Y, k.Bytes())
 		x2y2 := make([]byte, 64)
 		copy(x2y2[32-len(x2.Bytes()):], x2.Bytes())
@@ -175,6 +178,12 @@ func Decrypt(priv *ecdsa.PrivateKey, encryptData []byte) ([]byte, error) {
 
 	x1 := new(big.Int).SetBytes(encryptData[:32])
 	y1 := new(big.Int).SetBytes(encryptData[32:64])
+	if x1.Sign() == 0 && y1.Sign() == 0 {
+		return nil, errors.New("C1 is infinity")
+	}
+	if !c.IsOnCurve(x1, y1) {
+		return nil, errors.New("C1 is not on curve")
+	}
 
 	x2, y2 := c.ScalarMult(x1, y1, priv.D.Bytes())
 	c2 := make([]byte, 64)