How to get a Unique ID for the current user's logon session in windows - c#

Question

I need to get a value that uniquely identifies the current windows user\'s logon session. This is for a winforms app, not ASP.NET. I\'ll be retrieving this from within multi

Answer 1

As I understand, what you need is this:

SID: S-1-5-5-X-Y Name: Logon Session Description: A logon session. The X and Y values for these SIDs are different for each session.

Well-known security identifiers in Windows operating systems http://support.microsoft.com/kb/243330

Somebody asked for something similar here:

How to get the logon SID in C#

They have a good answer there, but I want to add my own

This is my solution:

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;


namespace TestLogonSid
{
    public partial class Form1 : Form
    {

        private delegate bool EnumDesktopProc(string lpszDesktop, IntPtr lParam);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click_1(object sender, EventArgs e)
        {

            this.textBox1.Text = GetLogonSid.getLogonSid();
        }


    }

    public class GetLogonSid
    {
        //The SID structure that identifies the user that is currently associated with the specified object. 
        //If no user is associated with the object, the value returned in the buffer pointed to by lpnLengthNeeded is zero. 
        //Note that SID is a variable length structure. 
        //You will usually make a call to GetUserObjectInformation to determine the length of the SID before retrieving its value.
        private const int UOI_USER_SID = 4;

        //GetUserObjectInformation function
        //Retrieves information about the specified window station or desktop object.
        [DllImport("user32.dll")]
        static extern bool GetUserObjectInformation(IntPtr hObj, int nIndex, [MarshalAs(UnmanagedType.LPArray)] byte[] pvInfo, int nLength, out uint lpnLengthNeeded);


        //GetThreadDesktop function
        //Retrieves a handle to the desktop assigned to the specified thread.
        [DllImport("user32.dll")]
        private static extern IntPtr GetThreadDesktop(int dwThreadId);


        //GetCurrentThreadId function
        //Retrieves the thread identifier of the calling thread.
        [DllImport("kernel32.dll")]
        public static extern int GetCurrentThreadId();

        //ConvertSidToStringSid function
        //The ConvertSidToStringSid function converts a security identifier (SID) to a string format suitable for display, storage, or transmission.
        //To convert the string-format SID back to a valid, functional SID, call the ConvertStringSidToSid function.

        [DllImport("advapi32", CharSet = CharSet.Auto, SetLastError = true)]
        static extern bool ConvertSidToStringSid(
            [MarshalAs(UnmanagedType.LPArray)] byte[] pSID,
            out IntPtr ptrSid);


        /// 

        /// The getLogonSid function returns the Logon Session string
        /// 
        /// 
        public static string getLogonSid()
        {
            string sidString = "";
            IntPtr hdesk = GetThreadDesktop(GetCurrentThreadId());
            byte[] buf = new byte[100];
            uint lengthNeeded;
            GetUserObjectInformation(hdesk, UOI_USER_SID, buf, 100, out lengthNeeded);
            IntPtr ptrSid;
            if (!ConvertSidToStringSid(buf, out ptrSid))
                throw new System.ComponentModel.Win32Exception();
            try
            {
                sidString = Marshal.PtrToStringAuto(ptrSid);
            }
            catch
            {
            }
            return sidString;
        }

    }
}