Comment utiliser PHP pour crypter et décrypter les cookies

<?php
class Cookie
{
    /**
     * 解密已经加密了的cookie
     * 
     * @param string $encryptedText
     * @return string
     */
    private static function _decrypt($encryptedText)
    {
        $key = Config::get(&#39;secret_key&#39;);
        $cryptText = base64_decode($encryptedText);
        $ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv = mcrypt_create_iv($ivSize, MCRYPT_RAND);
        $decryptText = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $cryptText, MCRYPT_MODE_ECB, $iv);
        return trim($decryptText);
    }
    /**
     * 加密cookie
     *
     * @param string $plainText
     * @return string
     */
    private static function _encrypt($plainText)
    {
        $key = Config::get(&#39;secret_key&#39;);
        $ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
        $iv = mcrypt_create_iv($ivSize, MCRYPT_RAND);
        $encryptText = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $plainText, MCRYPT_MODE_ECB, $iv);
        return trim(base64_encode($encryptText));
    }
    /**
     * 删除cookie
     * 
     * @param array $args
     * @return boolean
     */
    public static function del($args)
    {
        $name = $args[&#39;name&#39;];
        $domain = isset($args[&#39;domain&#39;]) ? $args[&#39;domain&#39;] : null;
        return isset($_COOKIE[$name]) ? setcookie($name, &#39;&#39;, time() - 86400, &#39;/&#39;, $domain) : true;
    }
    /**
     * 得到指定cookie的值
     * 
     * @param string $name
     */
    public static function get($name)
    {
        return isset($_COOKIE[$name]) ? self::_decrypt($_COOKIE[$name]) : null;
    }
    /**
     * 设置cookie
     *
     * @param array $args
     * @return boolean
     */
    public static function set($args)
    {
        $name = $args[&#39;name&#39;];
        $value= self::_encrypt($args[&#39;value&#39;]);
        $expire = isset($args[&#39;expire&#39;]) ? $args[&#39;expire&#39;] : null;
        $path = isset($args[&#39;path&#39;]) ? $args[&#39;path&#39;] : &#39;/&#39;;
        $domain = isset($args[&#39;domain&#39;]) ? $args[&#39;domain&#39;] : null;
        $secure = isset($args[&#39;secure&#39;]) ? $args[&#39;secure&#39;] : 0;
        return setcookie($name, $value, $expire, $path, $domain, $secure);
    }
}