<php

    //1.获取参数
    $timestamp = $_GET['timestamp'];
    $nonce = $_GET['nonce'];
    $token = 'weixin';//token必须与官网配置一致
    $signature = $_GET['signature'];

    //2.拼接，排序，加密参数
    $array = array($timestamp,$nonce,$token);
    sort($array);
    $tmpstr = implode('',$array);
    $tmpstr = sha1($tmpstr);

    //3.验证参数
    if ($tmpstr == $signature){
          echo $_GET['echostr'];  
          exit;
     } 

    ?>