Creating Secure Trial Versions for .NET Applications - A Tutorial

using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using System.IO;

namespace SampleTrialAppCS
{
    class ClockManipulationDetector
    {
        public static bool DetectClockManipulation(DateTime thresholdTime)
        {
            DateTime adjustedThresholdTime = new DateTime(thresholdTime.Year, thresholdTime.Month, thresholdTime.Day, 23, 59, 59);

            EventLog eventLog = new System.Diagnostics.EventLog("system");

            foreach (EventLogEntry entry in eventLog.Entries)
            {
                if (entry.TimeWritten > adjustedThresholdTime)
                    return true;
            }

            return false;
        }
    }
}