diff --git a/core/codec/aesecb.go b/core/codec/aesecb.go
index 08a388fb..1ec99a04 100644
--- a/core/codec/aesecb.go
+++ b/core/codec/aesecb.go
@@ -32,9 +32,11 @@ func NewECBEncrypter(b cipher.Block) cipher.BlockMode {
 	return (*ecbEncrypter)(newECB(b))
 }
 
+// BlockSize returns the mode's block size.
 func (x *ecbEncrypter) BlockSize() int { return x.blockSize }
 
-// why we don't return error is because cipher.BlockMode doesn't allow this
+// CryptBlocks encrypts a number of blocks. The length of src must be a multiple of
+// the block size. Dst and src must overlap entirely or not at all.
 func (x *ecbEncrypter) CryptBlocks(dst, src []byte) {
 	if len(src)%x.blockSize != 0 {
 		logx.Error("crypto/cipher: input not full blocks")
@@ -59,11 +61,13 @@ func NewECBDecrypter(b cipher.Block) cipher.BlockMode {
 	return (*ecbDecrypter)(newECB(b))
 }
 
+// BlockSize returns the mode's block size.
 func (x *ecbDecrypter) BlockSize() int {
 	return x.blockSize
 }
 
-// why we don't return error is because cipher.BlockMode doesn't allow this
+// CryptBlocks decrypts a number of blocks. The length of src must be a multiple of
+// the block size. Dst and src must overlap entirely or not at all.
 func (x *ecbDecrypter) CryptBlocks(dst, src []byte) {
 	if len(src)%x.blockSize != 0 {
 		logx.Error("crypto/cipher: input not full blocks")
diff --git a/core/codec/aesecb_test.go b/core/codec/aesecb_test.go
index 46a93ad7..a1117f3a 100644
--- a/core/codec/aesecb_test.go
+++ b/core/codec/aesecb_test.go
@@ -1,6 +1,7 @@
 package codec
 
 import (
+	"crypto/aes"
 	"encoding/base64"
 	"testing"
 
@@ -10,7 +11,8 @@ import (
 func TestAesEcb(t *testing.T) {
 	var (
 		key     = []byte("q4t7w!z%C*F-JaNdRgUjXn2r5u8x/A?D")
-		val     = []byte("hello")
+		val     = []byte("helloworld")
+		valLong = []byte("helloworldlong..")
 		badKey1 = []byte("aaaaaaaaa")
 		// more than 32 chars
 		badKey2 = []byte("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
@@ -31,6 +33,39 @@ func TestAesEcb(t *testing.T) {
 	src, err := EcbDecrypt(key, dst)
 	assert.Nil(t, err)
 	assert.Equal(t, val, src)
+	block, err := aes.NewCipher(key)
+	assert.NoError(t, err)
+	encrypter := NewECBEncrypter(block)
+	assert.Equal(t, 16, encrypter.BlockSize())
+	decrypter := NewECBDecrypter(block)
+	assert.Equal(t, 16, decrypter.BlockSize())
+
+	dst = make([]byte, 8)
+	encrypter.CryptBlocks(dst, val)
+	for _, b := range dst {
+		assert.Equal(t, byte(0), b)
+	}
+
+	dst = make([]byte, 8)
+	encrypter.CryptBlocks(dst, valLong)
+	for _, b := range dst {
+		assert.Equal(t, byte(0), b)
+	}
+
+	dst = make([]byte, 8)
+	decrypter.CryptBlocks(dst, val)
+	for _, b := range dst {
+		assert.Equal(t, byte(0), b)
+	}
+
+	dst = make([]byte, 8)
+	decrypter.CryptBlocks(dst, valLong)
+	for _, b := range dst {
+		assert.Equal(t, byte(0), b)
+	}
+
+	_, err = EcbEncryptBase64("cTR0N3dDKkYtSmFOZFJnVWpYbjJyNXU4eC9BP0QK", "aGVsbG93b3JsZGxvbmcuLgo=")
+	assert.Error(t, err)
 }
 
 func TestAesEcbBase64(t *testing.T) {
diff --git a/core/codec/dh_test.go b/core/codec/dh_test.go
index 951ff486..9f788b44 100644
--- a/core/codec/dh_test.go
+++ b/core/codec/dh_test.go
@@ -80,3 +80,17 @@ func TestKeyBytes(t *testing.T) {
 	assert.Nil(t, err)
 	assert.True(t, len(key.Bytes()) > 0)
 }
+
+func TestDHOnErrors(t *testing.T) {
+	key, err := GenerateKey()
+	assert.Nil(t, err)
+	assert.NotEmpty(t, key.Bytes())
+	_, err = ComputeKey(key.PubKey, key.PriKey)
+	assert.NoError(t, err)
+	_, err = ComputeKey(nil, key.PriKey)
+	assert.Error(t, err)
+	_, err = ComputeKey(key.PubKey, nil)
+	assert.Error(t, err)
+
+	assert.NotNil(t, NewPublicKey([]byte("")))
+}