short ticket, 產生短期門票

GenShortTicket.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace conShortSession
{
    class Program
    {
        static object __lockObj = new object();

        static void Main(string[] args)
        {
            for(int i=0;i<10;i++)
            {
                ulong ticket = GenShortTicket();
                bool isValid = VerifyShortTicket(ticket);

                Console.WriteLine($"ticket: {ticket}");
                Console.WriteLine($"isValue:{isValid}");
            }

            Console.WriteLine("Press any key to continue.");
            Console.ReadKey();
        }

        static ulong GenShortTicket()
        {
            lock (__lockObj)
            {
                ulong tickSeed = ((ulong)DateTime.Now.Ticks) + 12345678987654321u;
                System.Threading.SpinWait.SpinUntil(() => false, 97); //※Lock並等一小段時間以確保不重複

                byte[] by = BitConverter.GetBytes(tickSeed);
                byte[] by2 = new byte[by.Length];
                int[] rnd = new int[] { 7, 1, 5, 3, 4, 2, 6, 0 };
                for (int i = 0; i < by.Length; i++)
                {
                    by2[i] = (byte)(by[rnd[i]] ^ 0xAA);
                }

                ulong ticket = BitConverter.ToUInt64(by2, 0);
                return ticket;
            }
        }

        static bool VerifyShortTicket(ulong ticket)
        {
            byte[] by = BitConverter.GetBytes(ticket);
            byte[] by2 = new byte[by.Length];
            int[] rnd = new int[] { 7, 1, 5, 3, 4, 2, 6, 0 };
            for (int i = 0; i < by.Length; i++)
            {
                by2[i] = (byte)(by[rnd[i]] ^ 0xAA);
            }

            ulong tickSeed = BitConverter.ToUInt64(by2, 0);

            DateTime pre = new DateTime((long)(tickSeed - 12345678987654321u));
            bool isValid = (DateTime.Now.Subtract(pre).TotalSeconds < 2);
            return isValid;
        }
    }
}