diff --git a/go.mod b/go.mod
index 4e0e76e..e341693 100644
--- a/go.mod
+++ b/go.mod
@@ -4,5 +4,5 @@ go 1.16
 
 require (
 	golang.org/x/crypto v0.3.0
-	golang.org/x/sys v0.2.0
+	golang.org/x/sys v0.3.0
 )
diff --git a/go.sum b/go.sum
index 2f77b42..8555388 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,8 @@ github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5t
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.3.0 h1:a06MkbcxBrEFc0w0QIZWXrH/9cCX6KJyWbBOIwAn+7A=
+golang.org/x/crypto v0.3.0 h1:a06MkbcxBrEFc0w0QIZWXrH/9cCX6KJyWbBOIwAn+7A=
+golang.org/x/crypto v0.3.0/go.mod h1:hebNnKkNXi2UzZN1eVRvBB7co0a+JxK6XbPiWVs/3J4=
 golang.org/x/crypto v0.3.0/go.mod h1:hebNnKkNXi2UzZN1eVRvBB7co0a+JxK6XbPiWVs/3J4=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -15,8 +17,10 @@ golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
+golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
@@ -28,7 +32,3 @@ golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/crypto v0.3.0 h1:a06MkbcxBrEFc0w0QIZWXrH/9cCX6KJyWbBOIwAn+7A=
-golang.org/x/crypto v0.3.0/go.mod h1:hebNnKkNXi2UzZN1eVRvBB7co0a+JxK6XbPiWVs/3J4=
-golang.org/x/sys v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
-golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/sm2/sm2.go b/sm2/sm2.go
index a7a7286..98ef4d5 100644
--- a/sm2/sm2.go
+++ b/sm2/sm2.go
@@ -194,6 +194,10 @@ func (priv *PrivateKey) Decrypt(rand io.Reader, msg []byte, opts crypto.Decrypte
 
 const maxRetryLimit = 100
 
+var (
+	errCiphertextTooShort = errors.New("sm2: ciphertext too short")
+)
+
 // EncryptASN1 sm2 encrypt and output ASN.1 result, compliance with GB/T 32918.4-2016.
 func EncryptASN1(random io.Reader, pub *ecdsa.PublicKey, msg []byte) ([]byte, error) {
 	return Encrypt(random, pub, msg, ASN1EncrypterOpts)
@@ -203,7 +207,7 @@ func EncryptASN1(random io.Reader, pub *ecdsa.PublicKey, msg []byte) ([]byte, er
 func Encrypt(random io.Reader, pub *ecdsa.PublicKey, msg []byte, opts *EncrypterOpts) ([]byte, error) {
 	//A3, requirement is to check if h*P is infinite point, h is 1
 	if pub.X.Sign() == 0 && pub.Y.Sign() == 0 {
-		return nil, errors.New("sm2: invalid public key")
+		return nil, errors.New("sm2: public key point is the infinity")
 	}
 	if len(msg) == 0 {
 		return nil, nil
@@ -316,7 +320,7 @@ func Decrypt(priv *PrivateKey, ciphertext []byte) ([]byte, error) {
 func decrypt(priv *PrivateKey, ciphertext []byte, opts *DecrypterOpts) ([]byte, error) {
 	ciphertextLen := len(ciphertext)
 	if ciphertextLen <= 1+(priv.Params().BitSize/8)+sm3.Size {
-		return nil, errors.New("sm2: invalid ciphertext length")
+		return nil, errCiphertextTooShort
 	}
 	switch priv.Curve.Params() {
 	case P256().Params():
@@ -375,7 +379,7 @@ func parseCiphertext(c *sm2Curve, ciphertext []byte, opts *DecrypterOpts) (*_sm2
 	switch b {
 	case uncompressed:
 		if len(ciphertext) <= 1+2*byteLen+sm3.Size {
-			return nil, nil, nil, errors.New("sm2: invalid ciphertext length")
+			return nil, nil, nil, errCiphertextTooShort
 		}
 		C1, err := c.newPoint().SetBytes(ciphertext[:1+2*byteLen])
 		if err != nil {
@@ -920,7 +924,7 @@ func (curve *sm2Curve) pointToAffine(p *_sm2ec.SM2P256Point) (x, y *big.Int, err
 	out := p.Bytes()
 	if len(out) == 1 && out[0] == 0 {
 		// This is the encoding of the point at infinity.
-		return nil, nil, errors.New("ecdsa: public key point is the infinity")
+		return nil, nil, errors.New("sm2: public key point is the infinity")
 	}
 	byteLen := (curve.curve.Params().BitSize + 7) / 8
 	x = new(big.Int).SetBytes(out[1 : 1+byteLen])
diff --git a/sm2/sm2_legacy.go b/sm2/sm2_legacy.go
index c540e5b..f1e4e83 100644
--- a/sm2/sm2_legacy.go
+++ b/sm2/sm2_legacy.go
@@ -334,7 +334,7 @@ func PlainCiphertext2ASN1(ciphertext []byte, from ciphertextSplicingOrder) ([]by
 	curve := sm2ec.P256()
 	ciphertextLen := len(ciphertext)
 	if ciphertextLen <= 1+(curve.Params().BitSize/8)+sm3.Size {
-		return nil, errors.New("sm2: invalid ciphertext length")
+		return nil, errCiphertextTooShort
 	}
 	// get C1, and check C1
 	x1, y1, c3Start, err := bytes2Point(curve, ciphertext)
@@ -362,7 +362,7 @@ func AdjustCiphertextSplicingOrder(ciphertext []byte, from, to ciphertextSplicin
 	}
 	ciphertextLen := len(ciphertext)
 	if ciphertextLen <= 1+(curve.Params().BitSize/8)+sm3.Size {
-		return nil, errors.New("sm2: invalid ciphertext length")
+		return nil, errCiphertextTooShort
 	}
 
 	// get C1, and check C1