Kumara Kumara -4 years ago 92
C# Question

How get Current Username and password from windows operating System.

Story: I have a motherboard CD provided by Intel's original motherboard. When I install drivers it asks for username and password of the administrator account.

After every driver installs, the system will be restart and doesn't ask for the username and password.

My idea is that Windows should have a way to validate and enter username and password

Could you please let me know how to do this in C#, thanks.

Answer Source

I think this article might help you.

Let me know if you face any problem while understanding the code.

Edit 1 : I am confused with your question.

my idea: According above Windows shoud be provide some vay to validate and enter username and password

Do you want to validate a entered username and password?

Ahh, sorry for the delay. Here's the converted c# code

Add following namespaces:

using System.Security.Principal;
using System.Security.Permissions;
using System.Runtime.InteropServices;

And then here goes the main code :

namespace WindowsAccount
    public partial class Form1 : Form

        [DllImport("advapi32.dll", SetLastError = true)]
        public static extern bool LogonUser(string lpszUsername,
            string lpszDomain,
            string lpszPassword,
            int dwLogonType,
            int dwLogonProvider,
            out IntPtr phToken

        public static extern int FormatMessage(int dwFlags, ref IntPtr lpSource, int dwMessageId, int dwLanguageId, ref String lpBuffer, int nSize, ref IntPtr Arguments);

        [DllImport("kernel32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        static extern bool CloseHandle(IntPtr hObject);

        public static string GetErrorMessage(int errorCode)
            int FORMAT_MESSAGE_ALLOCATE_BUFFER = 0x100;
            int FORMAT_MESSAGE_IGNORE_INSERTS = 0x200;
            int FORMAT_MESSAGE_FROM_SYSTEM = 0x1000;

            int msgSize = 255;
            string lpMsgBuf = null;

            IntPtr lpSource = IntPtr.Zero;
            IntPtr lpArguments = IntPtr.Zero;
            int returnVal = FormatMessage(dwFlags, ref lpSource, errorCode, 0, ref lpMsgBuf, msgSize, ref lpArguments);

            if (returnVal == 0)
                throw new Exception("Failed to format message for error code " + errorCode.ToString() + ". ");
            return lpMsgBuf;


        public Form1()

        private void btnLogin_Click(object sender, EventArgs e)
            IntPtr tokenHandle = new IntPtr(0);

                string UserName = null;
                string MachineName = null;
                string Pwd = null;

                //The MachineName property gets the name of your computer.
                MachineName = System.Environment.MachineName;
                UserName = txtUser.Text;
                Pwd = txtPass.Text;

                const int LOGON32_PROVIDER_DEFAULT = 0;
                const int LOGON32_LOGON_INTERACTIVE = 2;
                tokenHandle = IntPtr.Zero;

                //Call the LogonUser function to obtain a handle to an access token.
                bool returnValue = LogonUser(UserName, MachineName, Pwd, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, out tokenHandle);

                if (returnValue == false)
                    //This function returns the error code that the last unmanaged function returned.
                    int ret = Marshal.GetLastWin32Error();
                    string errmsg = GetErrorMessage(ret);
                    //Create the WindowsIdentity object for the Windows user account that is
                    //represented by the tokenHandle token.

                    WindowsIdentity newId = new WindowsIdentity(tokenHandle);
                    WindowsPrincipal userperm = new WindowsPrincipal(newId);

                    //Verify whether the Windows user has administrative credentials.
                    if (userperm.IsInRole(WindowsBuiltInRole.Administrator))
                        MessageBox.Show("Access Granted. User is admin");
                        MessageBox.Show("Access Granted. User is not admin");

            catch (Exception ex)
                MessageBox.Show("Exception occurred. " + ex.Message);


Let me know if you face any problem.

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