How to implement Window Authentication Functionality to a C# Desktop Application

1)  Get currently logged in user details:
We can achieve this by using the WindowsIdentity class of System.Security.Principal namespace. This class provides a static method, getCurrent(), which return a object of WindowsIdentity.

2) Validate windows credentials provided by user:(Ask User Name, Domain and Password from user)
This is little complex compared to above as we need to call a windows API using IntropServices. To accomplish this we need to add a extern function declaration, and then call the function. Following code will help you to understand this better.

        public static extern bool LogonUser(string userName, string domainName, string password, int LogonType, int LogonProvider, ref IntPtr phToken);
        public Form1()

        private void btnLogin_Click(object sender, EventArgs e)
            bool issuccess = false;
            string username = GetloggedinUserName();

            if (username.ToLowerInvariant().Contains(txtUserName.Text.Trim().ToLowerInvariant()) && username.ToLowerInvariant().Contains(txtDomain.Text.Trim().ToLowerInvariant()))
                issuccess = IsValidateCredentials(txtUserName.Text.Trim(), txtPwd.Text.Trim(), txtDomain.Text.Trim());

            if (issuccess)
                MessageBox.Show("Successfuly Login !!!");
                MessageBox.Show("User Name / Password / Domain is invalid !!!");

        private string GetloggedinUserName()
            System.Security.Principal.WindowsIdentity currentUser = System.Security.Principal.WindowsIdentity.GetCurrent();
            return currentUser.Name;

        private bool IsValidateCredentials(string userName, string password, string domain)
            IntPtr tokenHandler = IntPtr.Zero;
            bool isValid = LogonUser(userName, domain, password, 2, 0, ref tokenHandler);
            return isValid;

You can also download a sample code from below link:

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4 Responses to How to implement Window Authentication Functionality to a C# Desktop Application

  1. mexicali82 says:


  2. Smantha J. says:

    Wonderful and really helpful. Thanks
    Though one question here, is there anyway we can get the windows password of currently logged-in user?

  3. Brian says:

    Thank you for this, I just have one question. When I try to authenticate a user with a blank password it always returns False. Any way to correct that?

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