Csharp/CSharp Tutorial/Security/WindowsIdentity

Determining group identity: WindowsBuiltInRole.PowerUser

using System;
using System.Security.Principal;
class MainClass
{
  public static void Main() 
  {
    WindowsIdentity wi = WindowsIdentity.GetCurrent();
    WindowsPrincipal prin = new WindowsPrincipal(wi);
    if (prin.IsInRole(WindowsBuiltInRole.PowerUser)) 
    {
      Console.WriteLine("You are a member of the Power User group");
    }
    else
    {
      Console.WriteLine("You are not a member of the Power User group");
    }
  }
}

You are not a member of the Power User group

Get current principal identity name

using System;
using System.Threading;
using System.Security;
using System.Security.Permissions;
using System.Collections.Generic;
using System.Text;
using System.Collections;
    class Program
    {
        static void Main(string[] args)
        {          
            System.Security.Principal.WindowsIdentity wi = System.Security.Principal.WindowsIdentity.GetCurrent();
            Thread.CurrentPrincipal = new System.Security.Principal.WindowsPrincipal(wi);
            Console.WriteLine(wi.Name);
            Console.WriteLine(Thread.CurrentPrincipal.Identity.Name);
            PrincipalPermission pp = new PrincipalPermission(null, "Administrators", true);
            pp.Demand();
            PrincipalPermission pp2 = new PrincipalPermission(null, "Users", true);
            pp.Union(pp2).Demand();
            try
            {
                PrincipalPermission pp3 = new PrincipalPermission(null, "Club");
                pp3.Demand();
            }
            catch (SecurityException e)
            {
                Console.WriteLine("You do not have access to the secret club.");
            }
        }
    }

Get the current identity

using System;
using System.Security.Principal;

class MainClass
{
  public static void Main() 
  {
    WindowsIdentity wi = WindowsIdentity.GetCurrent();
    Console.WriteLine("Identity information:");
    Console.WriteLine("  Authentication Type: {0}",wi.AuthenticationType);
    Console.WriteLine("  Is Anonymous: {0}", wi.IsAnonymous);
    Console.WriteLine("  Is Authenticated: {0}", wi.IsAuthenticated);
    Console.WriteLine("  Is Guest: {0}", wi.IsGuest);
    Console.WriteLine("  Is System: {0}", wi.IsSystem);
    Console.WriteLine("  Name: {0}", wi.Name);
    Console.WriteLine("  Token: {0}", wi.Token);
  }
}

Identity information:
  Authentication Type: NTLM
  Is Anonymous: False
  Is Authenticated: True
  Is Guest: False
  Is System: False
  Name: nfex\Joe
  Token: 1800

Get the current identity and its associated principal

using System;
using System.Security.Principal;

class MainClass
{
  public static void Main() 
  {
    WindowsIdentity wi = WindowsIdentity.GetCurrent();
    
    WindowsPrincipal prin = new WindowsPrincipal(wi);
    Console.WriteLine("Principal information:");
    Console.WriteLine("  Authentication Type: {0}", prin.Identity.AuthenticationType);
    Console.WriteLine("  Is authenticated: {0}", prin.Identity.IsAuthenticated);
    Console.WriteLine("  Name: {0}", prin.Identity.Name);
  }
}

Principal information:
  Authentication Type: NTLM
  Is authenticated: True
  Name: nfex\Joe

Impersonation

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.IsolatedStorage;
using System.Net;
using System.Net.Sockets;
using System.Reflection;
using System.Security;
using System.Security.AccessControl;
using System.Security.Policy;
using System.Security.Permissions;
using System.Security.Principal;
using System.Text;
public class MainClass
{
    public static void Main()
    {
        WindowsIdentity identity = WindowsIdentity.GetCurrent();
        WindowsImpersonationContext context = identity.Impersonate();
        context.Undo();
    }
}

Iterate through the group names to see if the current user is a member of each one

using System;
using System.Security.Principal;
class MainClass
{
    public static void Main (string[] args) 
    {
        
        WindowsIdentity identity = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(identity);
        
        foreach (string role in args) 
        {
            Console.WriteLine("Is {0} a member of {1}? = {2}", identity.Name, role, principal.IsInRole(role));
        }
    }
}

Obtain a WindowsIdentity object representing the currently logged on Windows user

using System;
using System.Security.Principal;
class MainClass
{
    public static void Main (string[] args) 
    {
        
        WindowsIdentity identity = WindowsIdentity.GetCurrent();
    }
}