<?php

class AES
{

    public $cipher = 'aes-128-cbc';
    public $secret = 've2HSq011whZYgKE';

    /**
     * 使用对称密钥进行加密
     * @param $plainText
     * @param $iv
     * @return string
     */
    function encrypt($plainText, $iv = null)
    {
        $plainText = json_encode($plainText);
        if (!empty($iv)) {
            $encryptedData = openssl_encrypt($plainText, $this->cipher, $this->secret, OPENSSL_RAW_DATA, $iv);
        } else {
            $encryptedData = openssl_encrypt($plainText, $this->cipher, $this->secret);
        }
        return base64_encode($encryptedData);
    }

    /**
     * 使用对称秘钥解密
     * @param $plainText
     * @param $iv
     * @return false|string
     */
    function decrypt($plainText, $iv = null) {
        $plainText = base64_decode($plainText);
        if (!empty($iv)) {
            $data = openssl_decrypt($plainText, $this->cipher, $this->secret, OPENSSL_RAW_DATA, $iv);
            $data = json_decode($data, true);
            return $data;
        }
        return openssl_decrypt($plainText, $this->cipher, $this->secret);
    }

    /**
     * 生成iv
     * @param int $timestamp 时间戳
     * @return false|string
     */
    public function buildIv(int $timestamp)
    {
        return substr(md5($this->secret . $timestamp), 5, 16);
    }

}