在PHP利用Cookie怎么实现一个倒计时功能

$this->systemSetKey(array(‘name‘=>$admin_info[‘admin_name‘], ‘id‘=>$admin_info[‘admin_id‘],‘gid‘=>$admin_info[‘admin_gid‘],‘sp‘=>$admin_info[‘admin_is_super‘]));//登陆成功之后做得事情

 /**
   * 系统后台 会员登录后 将会员验证内容写入对应cookie中
   *
   * @param string $name 用户名
   * @param int $id 用户ID
   * @return bool 布尔类型的返回结果
   */
  protected final function systemSetKey($user){
    setNcCookie(‘sys_key‘,encrypt(serialize($user),MD5_KEY),3600,‘‘,null);//设置cookie 过期时间为30分钟。这边设置cookie框架有带自己加密规则，具体是否需要加密自己看着设置。
  }

protected function __construct(){
    Language::read(‘common,layout‘);
    /**
     * 验证用户是否登录
     * $admin_info 管理员资料 name id
     */
    $this->admin_info = $this->systemLogin();//取得管理员的资料，之后的子类控制器继承构造方法
    if ($this->admin_info[‘id‘] != 1){
      // 验证权限
      $this->checkPermission();
    }
    //转码 防止GBK下用ajax调用时传汉字数据出现乱码
    if (($_GET[‘branch‘]!=‘‘ || $_GET[‘op‘]==‘ajax‘) && strtoupper(CHARSET) == ‘GBK‘){
      $_GET = Language::getGBK($_GET);
    }
  }
  /**
   * 系统后台登录验证
   *
   * @param
   * @return array 数组类型的返回结果
   */
  protected final function systemLogin(){
    //取得cookie内容，解密，和系统匹配
    $user = unserialize(decrypt(cookie(‘sys_key‘),MD5_KEY));//取cookie 里面储存的信息，现在使用的框架里面自定义了cookie的加密方式
    if (!key_exists(‘gid‘,(array)$user) || !isset($user[‘sp‘]) || (empty($user[‘name‘]) || empty($user[‘id‘]))){  //假如不存在说明用户没登陆或者用户长时间未操作cookie时间过期 跳到登陆页面去
      @header(‘Location: index.php?mod=login&action=login‘);exit;
    }else {
      $this->systemSetKey($user);//如果用户有登陆的话，每一个操作都会重写刷新cookie；
    }
    return $user;
  }

/**
 * 加密函数
 *
 * @param string $txt 需要加密的字符串
 * @param string $key 密钥
 * @return string 返回加密结果
 */
function encrypt($txt, $key = ‘‘){
  if (empty($txt)) return $txt;
  if (empty($key)) $key = md5(MD5_KEY);
  $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.";
  $ikey ="-x6g6ZWm2G9g_vr0Bo.pOq3kRIxsZ6rm";
  $nh2 = rand(0,64);
  $nh3 = rand(0,64);
  $nh4 = rand(0,64);
  $ch2 = $chars{$nh2};
  $ch3 = $chars{$nh3};
  $ch4 = $chars{$nh4};
  $nhnum = $nh2 + $nh3 + $nh4;
  $knum = 0;$i = 0;
  while(isset($key{$i})) $knum +=ord($key{$i++});
  $mdKey = substr(md5(md5(md5($key.$ch2).$ch3.$ikey).$ch4),$nhnum%8,$knum%8 + 16);
  $txt = base64_encode(time().‘_‘.$txt);
  $txt = str_replace(array(‘+‘,‘/‘,‘=‘),array(‘-‘,‘_‘,‘.‘),$txt);
  $tmp = ‘‘;
  $j=0;$k = 0;
  $tlen = strlen($txt);
  $klen = strlen($mdKey);
  for ($i=0; $i<$tlen; $i++) {
    $k = $k == $klen &#63; 0 : $k;
    $j = ($nhnum+strpos($chars,$txt{$i})+ord($mdKey{$k++}))%64;
    $tmp .= $chars{$j};
  }
  $tmplen = strlen($tmp);
  $tmp = substr_replace($tmp,$ch4,$nh3 % ++$tmplen,0);
  $tmp = substr_replace($tmp,$ch3,$nh2 % ++$tmplen,0);
  $tmp = substr_replace($tmp,$ch2,$knum % ++$tmplen,0);
  return $tmp;
}

/**
 * 解密函数
 *
 * @param string $txt 需要解密的字符串
 * @param string $key 密匙
 * @return string 字符串类型的返回结果
 */
function decrypt($txt, $key = ‘‘, $ttl = 0){
  if (empty($txt)) return $txt;
  if (empty($key)) $key = md5(MD5_KEY);
  $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.";
  $ikey ="-x6g6ZWm2G9g_vr0Bo.pOq3kRIxsZ6rm";
  $knum = 0;$i = 0;
  $tlen = @strlen($txt);
  while(isset($key{$i})) $knum +=ord($key{$i++});
  $ch2 = @$txt{$knum % $tlen};
  $nh2 = strpos($chars,$ch2);
  $txt = @substr_replace($txt,‘‘,$knum % $tlen--,1);
  $ch3 = @$txt{$nh2 % $tlen};
  $nh3 = @strpos($chars,$ch3);
  $txt = @substr_replace($txt,‘‘,$nh2 % $tlen--,1);
  $ch4 = @$txt{$nh3 % $tlen};
  $nh4 = @strpos($chars,$ch4);
  $txt = @substr_replace($txt,‘‘,$nh3 % $tlen--,1);
  $nhnum = $nh2 + $nh3 + $nh4;
  $mdKey = substr(md5(md5(md5($key.$ch2).$ch3.$ikey).$ch4),$nhnum % 8,$knum % 8 + 16);
  $tmp = ‘‘;
  $j=0; $k = 0;
  $tlen = @strlen($txt);
  $klen = @strlen($mdKey);
  for ($i=0; $i<$tlen; $i++) {
    $k = $k == $klen &#63; 0 : $k;
    $j = strpos($chars,$txt{$i})-$nhnum - ord($mdKey{$k++});
    while ($j<0) $j+=64;
    $tmp .= $chars{$j};
  }
  $tmp = str_replace(array(‘-‘,‘_‘,‘.‘),array(‘+‘,‘/‘,‘=‘),$tmp);
  $tmp = trim(base64_decode($tmp));
  if (preg_match("/\d{10}_/s",substr($tmp,0,11))){
    if ($ttl > 0 && (time() - substr($tmp,0,11) > $ttl)){
      $tmp = null;
    }else{
      $tmp = substr($tmp,11);
    }
  }
  return $tmp;
}