将两个字符串变量与返回布尔值的私有字典进行比较c#

我试图创建两个名为username和password的字符串变量，并返回一个名为authenticated的布尔值。我正试图将用户名和密码字符串与私有字典的内容进行比较。如果用户名和密码匹配，我希望布尔值设置为true。然而，我是c#的新手，真的不知道如何使用它。任何帮助都会很感激。下面是我已经有的。'

private Dictionary<string, string> dictionary = new Dictionary<string, string>();
        public Authenticator()
        {
            dictionary.Add("username1", "password1");
            dictionary.Add("username2", "password2");
            dictionary.Add("username3", "password3");
            dictionary.Add("username4", "password4");
            dictionary.Add("username5", "password5");
        }

        public Boolean Authenticate(Boolean authenticated)
        {
            //get user input 
            Console.WriteLine("Please enter a username");
            string inputUsername = Console.ReadLine();
          var auth1 = from entry in dictionary
                             where entry.Key == " ";
            Console.WriteLine("Please enter your password");
            string inputPassword = Console.ReadLine();
            var auth2 = from entry in dictionary
                        where entry.Value == " ";
                         `

    public bool Authenticate()
    {
        Console.WriteLine("Please enter a username");
        string inputUsername = Console.ReadLine();
        Console.WriteLine("Please enter your password");
        string inputPassword = Console.ReadLine();
        return dictionary.ContainsKey(inputUsername) && dictionary[inputUsername] == inputPassword;
    }