php实现cookie加密的方法

<?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('secret_key');
        $crypttext = base64_decode($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('secret_key');
        $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['name'];
        $domain = isset($args['domain']) ? $args['domain'] : null;
        return isset($_cookie[$name]) ? setcookie($name, '', time() - 86400, '/', $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['name'];
        $value= self::_encrypt($args['value']);
        $expire = isset($args['expire']) ? $args['expire'] : null;
        $path = isset($args['path']) ? $args['path'] : '/';
        $domain = isset($args['domain']) ? $args['domain'] : null;
        $secure = isset($args['secure']) ? $args['secure'] : 0;
        return setcookie($name, $value, $expire, $path, $domain, $secure);
    }
}