<%@ Page Language="C#"  %>
<script runat="Server" >
    //此处TOKEN可以自行修改
    public const String TOKEN = "weixin_kevinlc"; 
    
    private void Page_Load(object sender, EventArgs e)
    {
         String echoStr = Request["echostr"];

        if(this.checkSignature()){
            Response.Write(echoStr);
        }
    }
    //验证
    private bool checkSignature(){
        string signature = Request["signature"];
        string timestamp = Request["timestamp"];
        string nonce = Request["nonce"];    
                
        string token = TOKEN;
        string[] tmpArr = new string[]{token, timestamp, nonce};
        Array.Sort(tmpArr);
        string tmpStr = string.Join("",tmpArr);
        //sha1加密
        System.Security.Cryptography.SHA1 sha1 = new System.Security.Cryptography.SHA1CryptoServiceProvider(); 
        byte[] secArr = sha1.ComputeHash(System.Text.Encoding.Default.GetBytes(tmpStr));
        tmpStr =  BitConverter.ToString(secArr).Replace("-","").ToLower();
        if( tmpStr == signature ){
            return true;
        }else{
            return false;
        }  
    }
</script>