$secret = '{{secret}}'; //用户秘钥
$params = array();
$params['topic'] = '{{topic}}'; //消息主题
$params['pub_time'] = '{{pub-time}}'; //原消息发布时间
$params['data'] = '{{data}}'; //消息内容
ksort($params); //排序
$str='';
foreach($params as $k => $v)
{
    $str .= ($k . $v);
}
$str = $secret . $str . $secret; //拼接签名原串
$sign = md5($str); //签名计算
echo($sign);
