<?PHP

//1、将timestamp,nonce,token 按字典序排序
$timestamp = $_GET['timestamp'];
$nonce = $_GET['nonce'$token = 'weixin';   你在公众平台上填写的token
$signature = $_GET['signature'$arr = array( $timestamp,$nonce,1)">$token );
sort($arr);

2、将排序后的3个参数拼接后用sha1加密
$tmpstr = implode('',1)">);
sha1($tmpstr3、将加密后的字符串与signature进行对比，判断该请求是否来自微信
if($tmpstr == $signature){
    echo $_GET['echostr'];
    exit;
}