using System;

using System.Collections.Generic;

using System.DirectoryServices.AccountManagement;

​

public class AuthenticationService

{

    private const string ActiveDirectoryDomain = "corp.example.com";

​

    // Simulate AD users for testing purposes

    private static readonly Dictionary<string, string> _testUsers = new Dictionary<string, string>()

    {

        {"user1", "password123"},

        {"test.user", "secure_password"},

        {"guest", "guest"}

    };

​

    public bool AuthenticateUser(string username, string password)

    {

        if (string.IsNullOrWhiteSpace(username) || string.IsNullOrWhiteSpace(password))

        {

            return false; // Do not reveal the reason

        }

​

        try

        {

            // Simulate AD authentication

            if (_testUsers.ContainsKey(username) && _testUsers[username] == password)

            {

                return true;

            }

            else

            {

                return false; // Do not reveal the reason

            }

        }

        catch (Exception)

        {

            return false; // Do not reveal the reason

        }

    }

​

    public static void Main(string[] args)

    {

        AuthenticationService authService = new AuthenticationService();

​

        Console.WriteLine($"Attempting to authenticate user 'user1': {authService.AuthenticateUser("user1", "password123")}");

        Console.WriteLine($"Attempting to authenticate user 'user1' with wrong password: {authService.AuthenticateUser("user1", "wrongpassword")}");

        Console.WriteLine($"Attempting to authenticate user 'nonexistent': {authService.AuthenticateUser("nonexistent", "anypassword")}");

        Console.WriteLine($"Attempting to authenticate with empty username: {authService.AuthenticateUser("", "password")}");

        Console.WriteLine($"Attempting to authenticate with empty password: {authService.AuthenticateUser("user", "")}");

        Console.WriteLine($"Attempting to authenticate with null username: {authService.AuthenticateUser(null, "password")}");

        Console.WriteLine($"Attempting to authenticate with null password: {authService.AuthenticateUser("user", null)}");

    }

}