Golang 微信小程序加密数据解密算法实现

func DecryptData (app_id, session_key, iv, encrypted_data string) (map[string]interface{}, error) {
  if len := strings.Count(session_key, "") - 1; len != 24 {
    return nil, errors.New("Invalid value session_key!")
  }
  aesKey, err := base64.StdEncoding.DecodeString(session_key)
  if err != nil {
    return nil, err
  }
  if len := strings.Count(iv, "") - 1; len != 24 {
    return nil, errors.New("Invalid value iv!")
  }
  ivKey, err := base64.StdEncoding.DecodeString(iv)
  if err != nil {
    return nil, err
  }
  decodeData, err := base64.StdEncoding.DecodeString(encrypted_data)
  if err != nil {
    return nil, err
  }
  dataBytes, err := AesDecrypt(decodeData, aesKey, ivKey)
  if err != nil {
    return nil, err
  }
  var result map [string] interface{}
  err = json.Unmarshal(dataBytes, &result)
  watermark := result["watermark"].(map[string]interface{})
  if watermark["appid"] != app_id {
    return nil, errors.New("Invalid appid data!")
  }
  return result, err
}

func AesDecrypt(crypted, key, iv []byte) ([]byte, error) {
  block, err := aes.NewCipher(key)
  if err != nil {
    return nil, err
  }
  blockMode := cipher.NewCBCDecrypter(block, iv)
  origData := make([]byte, len(crypted))
  blockMode.CryptBlocks(origData, crypted)
    // 去除填充
  length := len(origData)
  unp := int(origData[length-1])
  return origData[:(length - unp)], nil
}