System.DateTime.now and how to avoid time cheats

Hi,

I want to reward my player if he comes back to my game every day.

The obvious solution for this would be something like:

Code (csharp):

1.     DateTime currentTime = DateTime.Now;
2.     TimeSpan ts = currentTime - Convert.ToDateTime (GameParameters.lastPlayDate);
3.     if (ts.TotalHours > 24)
4.     {
5.        Debug.Log ("Welcome back, here's a prize for you!");
6.     }

But, this approach can be exploited by changing the time and date on my device. I'd like to avoid that, I've look for an answer here, in Unity forums and in game dev in general and I couldn't find any answer...

Is there any way to avoid this cheat at all? Either locally or, say, getting time and date from a server via Unity?

Thanks in advance!

 

The only way is to use the time on a server. Anything local can be changed.

--Eric

 

Thanks, Eric. I thought that would be the answer (unfortunately...)

Do you have any suggestion of time server that I can use?

Thanks,

Jay_Santos

 

I just wrote this without testing it but it should work. I don't really know what time format you get from unity so you might need to let something else return from the php script to be able to check it with the time in unity, but this script will get you the unix timestamp from the server

for more info about the time/date outputs you can do with php check these 2 links:
http://www.php.net/manual/en/function.time.php
http://www.php.net/manual/en/function.date.php

CommunicationController.js // This is how I always name this script

Code (csharp):

1.  
2. var phpController = "http://yourwebsite.com/folder/phpcontroller.php";
3.  
4. function GetServerTime() {
5.     var posurl : String = phpController + "?action=getservertime";
6.     var posgetwww : WWW = WWW(posurl);
7.     //yield posgetwww;
8.     if(posgetwww.error) {
9.         // error... epic FAIL!
10.         print("There was an error saving the level: " + posgetwww.error);
11.     } else {
12.         // no errors... WIN!
13.         return posgetwww.text;
14.     }
15. }
16.  

phpcontroller.php

Code (csharp):

1.  
2. <?php
3.     if(isset($_GET['action']) == "getservertime"){
4.         echo time(); // Outputs the unix timestamp
5.     }
6. ?>
7.  

 

I've made a plugin for this task which works in offline mode (iOS and Android). It may be useful even if you use server timestamps, because user can turn off network and then cheat.

Thread: http://forum.unity3d.com/threads/time-cheating-prevention-in-offline-mode-ios-android.256735/

 

How about Windows Platform??? Any plugin for window??

 

you could also use pool.ntp.org to get the network time like so (obviously you'll need to be online for this, but you won't need your own server script):

Code (CSharp):

1.     public static double NtpTime ()
2.     {
3.         try
4.         {
5.             byte[] ntpData = new byte[48];
6.      
7.             //LeapIndicator = 0 (no warning), VersionNum = 3 (IPv4 only), Mode = 3 (Client Mode)
8.             ntpData[0] = 0x1B;
9.      
10.             IPAddress[] addresses = Dns.GetHostEntry ("pool.ntp.org").AddressList;
11.             Socket socket = new Socket (AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
12.      
13.             socket.Connect (new IPEndPoint (addresses[0], 123));
14.             socket.ReceiveTimeout = 1000;
15.      
16.             socket.Send (ntpData);
17.             socket.Receive (ntpData);
18.             socket.Close ();
19.      
20.             ulong intc = (ulong) ntpData[40] << 24 | (ulong) ntpData[41] << 16 | (ulong) ntpData[42] << 8 | (ulong) ntpData[43];
21.             ulong frac = (ulong) ntpData[44] << 24 | (ulong) ntpData[45] << 16 | (ulong) ntpData[46] << 8 | (ulong) ntpData[47];
22.      
23.             return (double) ((intc * 1000) + ((frac * 1000) / 0x100000000L));
24.         }
25.         catch (Exception exception)
26.         {
27.             Debug.Log ("Could not get NTP time");
28.             Debug.Log (exception);
29.             return LocalTime ();
30.         }
31.     }
32.  
33.     public static double LocalTime ()
34.     {
35.         return DateTime.Now.Subtract (new DateTime (1900, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds;
36.     }

 

Thanks, helped me a lot.
I'm just wondering why NtpTime return TotalMilliseconds, but LocalTime return TotalSeconds instead?

 

Hi, how to you convert it in seconds and minutes ? and how to make a difference ?

thank you

 

http://leatonm.net/unity-tutorial/unity3d-internet-time-and-date-guide/

working fine for me.