using System;
using System.Collections.Generic;
using System.Text;

using System.Runtime.InteropServices; // DllImport
using System.Security.Principal; // WindowsImpersonationContext
using System.Security.Permissions; // PermissionSetAttribute


namespace Inpersonation
{
    class Inpersonater
    {
        // Get Token
        [DllImport("advapi32.dll", SetLastError = true)]
        public static extern bool LogonUser(string pszUsername, string pszDomain, string pszPassword,
            int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

        // Return from context
        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public extern static bool CloseHandle(IntPtr handle);

        public static void DoWorkUnderImpersonation()
        {
            WindowsImpersonationContext impersonationContext = null;
            IntPtr userHandle = IntPtr.Zero;
            const int LOGON32_PROVIDER_DEFAULT = 0;
            const int LOGON32_LOGON_INTERACTIVE = 2;
            Console.Write("Domain: ");
            string domain = Console.ReadLine();
            Console.Write("Login: ");
            string user = Console.ReadLine();
            Console.Write("Password: ");
            string password = "";
            ConsoleKeyInfo key;
            do
            {
                key = Console.ReadKey(true);

                if (key.Key != ConsoleKey.Backspace && key.Key != ConsoleKey.Enter)
                {
                    password += key.KeyChar;
                    Console.Write("*");
                }
                else
                {
                    if (key.Key == ConsoleKey.Backspace && password.Length > 0)
                    {
                        password = password.Substring(0, (password.Length - 1));
                        Console.Write("\b \b");
                    }
                }
            }
            // Stops Receving Keys Once Enter is Pressed
            while (key.Key != ConsoleKey.Enter);
            Console.WriteLine("");
            try
            {
                if (domain == "")
                    domain = System.Environment.MachineName;

                bool loggedOn = LogonUser(user,
                                            domain,
                                            password,
                                            LOGON32_LOGON_INTERACTIVE,
                                            LOGON32_PROVIDER_DEFAULT,
                                            ref userHandle);

                if (!loggedOn)
                {
                    Console.WriteLine("Exception impersonating user, error code: " + Marshal.GetLastWin32Error());
                    return;
                }

                impersonationContext = WindowsIdentity.Impersonate(userHandle);

                //(WindowsIdentity.GetCurrent().Name);

                string text = System.IO.File.ReadAllText(@"C:\secret.txt");
                Console.WriteLine(text);

            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception impersonating user: " + ex.Message);
            }
            finally
            {
                if (impersonationContext != null)
                {
                    impersonationContext.Undo();
                }

                if (userHandle != IntPtr.Zero)
                {
                    CloseHandle(userHandle);
                }
            }
        }

        public static void Main()
        {
            DoWorkUnderImpersonation();
        }
    }

}