using System;
using System.Collections.Generic;
using System.Data.Objects;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication25
{
    class Program
    {
        [DllImport("advapi32.dll", SetLastError = true)]
        public static extern bool LogonUser(
            string lpszUsername,
            string lpszDomain,
            string lpszPassword,
            int dwLogonType,
            int dwLogonProvider,
            out IntPtr phToken
            );

        static int Main(string[] args)
        {
            Console.WriteLine(WindowsIdentity.GetCurrent().Name);

            IntPtr ut;            
            if (!LogonUser("User2", string.Empty, "123", 2, 0, out ut))
                return -1;
            
            using (var impCtx = WindowsIdentity.Impersonate(ut))
            {
                System.IO.File.Copy(@"c:\temp\data.txt", @"c:\temp\data2.txt");
                Console.WriteLine(WindowsIdentity.GetCurrent().Name);
                
            }

            Console.WriteLine(WindowsIdentity.GetCurrent().Name);

            return 0;
        }
    }
}