using System;

using System.Linq;

using System.Threading;

​

public class Program

{

    public static void Main()

    {

        var ogTime = DateTime.UtcNow;

        Console.WriteLine("ORIGINAL DATETIME: {0}",  ogTime);

        Console.WriteLine("___________________________________________\n");

        // ==== CREATE A TOKEN W/ A DATETIME IN IT ====

        // Convert our DateTime object into bytes

        byte[] time = BitConverter.GetBytes(ogTime.ToBinary());

        Console.WriteLine("ORIGINAL DATETIME BYTES: {0}\n",  BitConverter.ToString(time));

        // Bake the DateTime into a GUID

        byte[] key = Guid.NewGuid().ToByteArray();

        string token = Convert.ToBase64String(time.Concat(key).ToArray());

        Console.WriteLine("STRING TOKEN: {0}\n",  token);

        // ==== NOW LET'S REVERSE THE PROCESS TO GET THE DATETIME BACK ====

        // Deserialize the token with our DateTime in it

        byte[] tokenBytes = Convert.FromBase64String(token);

        // Convert the bytes into a 64-bit signed integer

        long arg = BitConverter.ToInt64(tokenBytes, 0);

        Console.WriteLine("64-BIT INT ARG FOR DATETIME.FROMBINARY(): {0}\n",  arg);

        // Feed the 64-bit signed integer into a static DateTime method 

        // to rebuild a copy of our original DateTime object

        DateTime rebuiltDateTime = DateTime.FromBinary(arg);

        Console.WriteLine("___________________________________________\n");

        Console.WriteLine("REBUILT DATETIME: {0}\n",  rebuiltDateTime);

        // Now you can write any time requirement conditions against rebuilt DateTime that you need for validation

        var seconds = 4;

        Thread.Sleep(3000);

        if (rebuiltDateTime > DateTime.UtcNow.AddSeconds(-seconds))

        {

            Console.WriteLine("It has been LESS than 4 seconds since the token was generated.");

            // Do stuff 

        }

        if (rebuiltDateTime < DateTime.UtcNow.AddSeconds(-seconds))

        {

            Console.WriteLine("It has been MORE than 4 seconds since the token was generated.");    

            // Do stuff 

        }

    }

}