Question

I’ve written a smaall app in c#. I want this app to lock on unlock a workstation on my own login.

Locking the workstation is quite simple and it works fine.

The problem starts when i want to unlock the workstation.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Threading;
using System.Security.Principal;
using System.Security.Permissions;
using System.Drawing;


namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    [DllImport("User32.dll")]
    public static extern IntPtr GetDC(IntPtr hwnd);

    [DllImport("User32.dll")]
    public static extern void ReleaseDC(IntPtr dc);

    IntPtr desktopDC;
    Graphics g;

    public static class Logon
    {
        [DllImport("User32.Dll", EntryPoint = "LockWorkStation"), Description("Locks the workstation's display. Locking a workstation protects it from unauthorized use.")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool LockWorkStation();

        /// <exception cref="Win32Exception">if the lock fails more information can be found in this Exception class</exception>
        public static void LockWorkstation()
        {
            if (!LockWorkStation())
                throw new Win32Exception(Marshal.GetLastWin32Error());
        }

        [DllImport("advapi32.dll", EntryPoint = "LogonUser")]
        public static extern bool LogonUser(

        string lpszUsername,

        string lpszDomain,

        string lpszPassword,

        int dwLogonType,

        int dwLogonProvider,

        ref IntPtr phToken);
    }

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        Logon.LockWorkstation();
        timer1.Start();   
    }

    private void timer1_Tick(object sender, EventArgs e)
    {
        timer1.Stop();
        Login();
    }

    private void Login()
    {
        string sUsername = "adam";
        string sDomain = System.Environment.MachineName;
        string sPassword = "sernik";

        const int LOGON32_PROVIDER_DEFAULT = 0;
        // create token

        const int LOGON32_LOGON_INTERACTIVE = 2;
        //const int SecurityImpersonation = 2;


        IntPtr pExistingTokenHandle = new IntPtr(0);
        IntPtr pDuplicateTokenHandle = new IntPtr(0);
        pExistingTokenHandle = IntPtr.Zero;
        pDuplicateTokenHandle = IntPtr.Zero;


        bool a = Logon.LogonUser(sUsername, sDomain, sPassword, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref pExistingTokenHandle);

        g.DrawString(a.ToString(), new Font(FontFamily.GenericSansSerif, 80), Brushes.Red, 100, 100);
    }

    private void button2_Click(object sender, EventArgs e)
    {
        Login();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        desktopDC = GetDC(IntPtr.Zero);

        g = Graphics.FromHdc(desktopDC);
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        g.Dispose();
        ReleaseDC(desktopDC);
    }
}
}

I was trying the LogonUser method but it only gives my true or false result and don’t acually unlocks the screen.

How to do this under windows 7?

The puprose of the app is to detect presence of an electronic key plugged into PC and lock or unlock workstation then.

Answer 1

The puprose of the app is to detect presence of an electronic key plugged into PC and lock or unlock workstation then.

Prior to Windows Vista you could do something like this with GINA, since you mention Windows 7 you’ll have to use the new infrastructure. Either way, you can’t acheive this sort of behavior by simply running a program on the machine in question, you need to tie into the authentication systems of Windows.