diff --git a/crypto/crypto.go b/crypto/crypto.go
new file mode 100644
index 0000000..8aee53f
--- /dev/null
+++ b/crypto/crypto.go
@@ -0,0 +1,18 @@
+package crypto
+
+// 对称加密
+type ISymmetric interface {
+	Encrypt(msg []byte) ([]byte, error)
+	Decrypt(cipherText []byte) ([]byte, error)
+}
+
+// 非对称加密
+type IAsymmetric interface {
+	Encrypt(msg []byte) ([]byte, error)
+	Decrypt(ciphertext []byte) ([]byte, error)
+}
+
+type Signer interface {
+	Sign(msg []byte) ([]byte, error)
+	Verify(msg, sign []byte) bool
+}
diff --git a/crypto/ecdsa.go b/crypto/ecdsa.go
index 45d8d7d..13d536d 100644
--- a/crypto/ecdsa.go
+++ b/crypto/ecdsa.go
@@ -3,6 +3,7 @@ package crypto
 import (
 	"crypto"
 	"crypto/ecdsa"
+	"crypto/rand"
 	"crypto/x509"
 	"encoding/pem"
 	"errors"
@@ -10,6 +11,8 @@ import (
 	"strconv"
 )
 
+// var _ Signer = &ecdsaOptions{}
+
 type ecdsaOptions struct {
 	hashOptions
 	prv *ecdsa.PrivateKey
@@ -89,12 +92,16 @@ func ParsePublicKey(pem []byte) Option {
 	return publicKeyOption(pem)
 }
 
+func (opt *ecdsaOptions) Sign(msg []byte) ([]byte, error) {
+	sum := opt.getHash(msg)
+	return ecdsa.SignASN1(rand.Reader, opt.prv, sum)
+}
+
 func (opt *ecdsaOptions) Verify(msg, rText, sText []byte) bool {
 	var r, s big.Int
 	_ = r.UnmarshalText(rText)
 	_ = s.UnmarshalText(sText)
 
 	sum := opt.getHash(msg)
-
 	return ecdsa.Verify(opt.pub, sum, &r, &s)
 }
diff --git a/crypto/rsa.go b/crypto/rsa.go
index 3ed67e9..b39c97c 100644
--- a/crypto/rsa.go
+++ b/crypto/rsa.go
@@ -10,7 +10,7 @@ import (
 	"strconv"
 )
 
-
+var _ IAsymmetric = &rsaInstance{}
 
 type rsaInstance struct {
 	hashOptions
diff --git a/crypto/sm2.go b/crypto/sm2.go
index f08033b..53068f5 100644
--- a/crypto/sm2.go
+++ b/crypto/sm2.go
@@ -15,6 +15,8 @@ var (
 	C1C2C3      = 1
 )
 
+var _ IAsymmetric = &sm2Instance{}
+
 type sm2Instance struct {
 	mode int
 	prk  *s.PrivateKey
diff --git a/crypto/sm4.go b/crypto/sm4.go
index 48501fd..f2c397a 100644
--- a/crypto/sm4.go
+++ b/crypto/sm4.go
@@ -6,6 +6,8 @@ import (
 	"github.com/tjfoc/gmsm/sm4"
 )
 
+var _ ISymmetric = &sm4EcbInstance{}
+
 type sm4Instance struct {
 	key []byte
 }