code: function _deciph(user_id) {
    let decipher = crypto.createDecipher('aes-256-cbc', key);
    let dec = decipher.update(user_id, 'hex', 'utf8');
    dec += decipher.final('utf8'); //解密之后的值
  
    return JSON.parse(dec);
  }
docs: 加密的秘钥