PHP mcrypt 暗号化拡張機能とは何ですか? mcrypt 拡張機能の詳細な紹介

<?php
    /* 打开加密算法和模式 */
    $td = mcrypt_module_open(&#39;rijndael-256&#39;, &#39;&#39;, &#39;ofb&#39;, &#39;&#39;);

    /* 创建初始向量，并且检测密钥长度。 
     * Windows 平台请使用 MCRYPT_RAND。 */
    $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);
    $ks = mcrypt_enc_get_key_size($td);

    /* 创建密钥 */
    $key = substr(md5(&#39;very secret key&#39;), 0, $ks);

    /* 初始化加密 */
    mcrypt_generic_init($td, $key, $iv);

    /* 加密数据 */
    $encrypted = mcrypt_generic($td, &#39;This is very important data&#39;);

    /* 结束加密，执行清理工作 */
    mcrypt_generic_deinit($td);

    /* 初始化解密模块 */
    mcrypt_generic_init($td, $key, $iv);

    /* 解密数据 */
    $decrypted = mdecrypt_generic($td, $encrypted);

    /* 结束解密，执行清理工作，并且关闭模块 */
    mcrypt_generic_deinit($td);
    mcrypt_module_close($td);

    /* 显示文本 */
    echo trim($decrypted) . "\n";
?>

<?php
/**
 * PHP AES加密解密类
 * Created by PhpStorm.
 * User: ahao
 * Date: 2016/11/3
 * Time: 0:03
 */
class PubEncrypt{
    public static $key = &#39;123454536f667445454d537973576562&#39;;  // 默认的key

    /**
     * AES加密
     * @param $data  明文
     * @param null $key  加密密钥
     * @return array|string
     */
    public static function AesEncrypt($data, $key = null){
        $data = trim($data);
        if($data == &#39;&#39;) return &#39;&#39;;
        try{
            if(!extension_loaded(&#39;mcrypt&#39;))
                throw new Exception(&#39;当前PHP环境没有加载mcrypt扩展&#39;);

            // 打开加密算法和模式
            $module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, &#39;&#39;, MCRYPT_MODE_CBC, &#39;&#39;);

            $key = self::substr($key == null ? self::$key : $key, 0, mcrypt_enc_get_key_size($module));
            $iv = substr(md5($key), 0, mcrypt_enc_get_iv_size($module));

            // 初始化加密
            mcrypt_generic_init($module, $key, $iv);

            // 加密数据
            $encrypt = mcrypt_generic($module, $data);

            // 反初始化释放资源
            mcrypt_generic_deinit($module);

            // 关闭资源对象退出
            mcrypt_module_close($module);
            return array(&#39;status&#39; => true, &#39;data&#39; => base64_encode($encrypt));
        }catch (Exception $e){
            $error = $e->getMessage();
            $data = array(
                &#39;status&#39; => false,
                &#39;msg&#39; => $error
            );
            return $data;
        }
    }

    /**
     * AES解密
     * @param $encrypted  密文
     * @param null $key  解密密钥
     * @return array|string
     */
    public static function AesDecrypt($encrypted, $key = null){
        $encrypted = trim($encrypted);
        if($encrypted == &#39;&#39;)  return &#39;&#39;;
        try{
            if(!extension_loaded(&#39;mcrypt&#39;))
                throw new Exception(&#39;当前PHP环境没有加载mcrypt扩展&#39;);

            $encrypted = base64_decode($encrypted);
            $module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, &#39;&#39;, MCRYPT_MODE_CBC, &#39;&#39;);

            $key = self::substr($key == null ? self::$key : $key, 0, mcrypt_enc_get_key_size($module));
            $iv = substr(md5($key), 0, mcrypt_enc_get_iv_size($module));

            mcrypt_generic_init($module, $key, $iv);
            $decrypted = mdecrypt_generic($module, $encrypted);
            mcrypt_generic_deinit($module);
            mcrypt_module_close($module);
            return array(&#39;status&#39; => true, &#39;data&#39; => rtrim($decrypted,"\0"));
        }catch (Exception $e){
            $error = $e->getMessage();
            $data = array(
                &#39;status&#39; => false,
                &#39;msg&#39; => $error
            );
            return $data;
        }
    }


    /**
     * 截取字符串
     * @param $string  被截取的字符串
     * @param $start   起始位置
     * @param $length  截取长度
     * @return string  截取到的字符串
     */
    private static function substr($string, $start, $length)
    {
        return extension_loaded(&#39;mbstring&#39;) ? mb_substr($string,$start,$length,&#39;8bit&#39;) : substr($string,$start,$length);
    }
}