func TestGenerateSignature(t *testing.T) {
   // test data
   secretKey := "MBMIvsoijBSTqLPoCHYinLXKvlaCKfev"
   timestamp := fmt.Sprintf("%v", time.Now().UnixMilli())
   encryptBytes, err := EncryptECB([]byte(timestamp), []byte(secretKey))
   if err != nil {
      fmt.Println(err)
   }
   signature := hex.EncodeToString(encryptBytes)
   fmt.Println(signature)
}

func EncryptECB(plaintext, secretKey []byte) ([]byte, error) {

   block, err := aes.NewCipher(secretKey)
   if err != nil {
      return nil, errors.Errorf("Error: NewCipher(%d bytes) = %s", len(secretKey), err)
   }
   padded := PKCS7Padding(plaintext, block.BlockSize())
   ciphertext := make([]byte, len(padded))

   for bs, be := 0, block.BlockSize(); bs < len(padded); bs, be = bs+block.BlockSize(), be+block.BlockSize() {
      block.Encrypt(ciphertext[bs:be], padded[bs:be])
   }

   return ciphertext, nil
}
func PKCS7Padding(ciphertext []byte, blockSize int) []byte {
   padding := blockSize - len(ciphertext)%blockSize
   padtext := bytes.Repeat([]byte{byte(padding)}, padding)
   return append(ciphertext, padtext...)
}