Password masking console application

Question

I tried the following code...

string pass = "";
Console.Write("Enter your password: ");
ConsoleKeyInfo key;

do
{
    key = Console.ReadKey(true);

    // Backspace Should Not Work
    if (key.Key != ConsoleKey.Backspace)
    {
        pass += key.KeyChar;
        Console.Write("*");
    }
    else
    {
        Console.Write("\b");
    }
}
// Stops Receving Keys Once Enter is Pressed
while (key.Key != ConsoleKey.Enter);

Console.WriteLine();
Console.WriteLine("The Password You entered is : " + pass);

But this way the backspace functionality doesn't work while typing the password. Any suggestion?

Answer 1

Here's a version that adds support for the Escape key (which returns a null string)

public static string ReadPassword()
{
    string password = "";
    while (true)
    {
        ConsoleKeyInfo key = Console.ReadKey(true);
        switch (key.Key)
        {
            case ConsoleKey.Escape:
                return null;
            case ConsoleKey.Enter:
                return password;
            case ConsoleKey.Backspace:
                password = password.Substring(0, (password.Length - 1));
                Console.Write("\b \b");
                break;
            default:
                password += key.KeyChar;
                Console.Write("*");
                break;
        }
    }
}

Answer 2

If I understand this correctly, you're trying to make backspace delete both the visible * character on screen and the cached character in your pass variable?

If so, then just change your else block to this:

            else
            {
                Console.Write("\b");
                pass = pass.Remove(pass.Length -1);
            }

Answer 3

Taking the top answer, as well as the suggestions from it's comments, and modifying it to use SecureString instead of String, test for all control keys, and not error or write an extra "*" to the screen when the password length is 0, my solution is:

public static SecureString getPasswordFromConsole(String displayMessage) {
    SecureString pass = new SecureString();
    Console.Write(displayMessage);
    ConsoleKeyInfo key;

    do {
        key = Console.ReadKey(true);

        // Backspace Should Not Work
        if (!char.IsControl(key.KeyChar)) {
            pass.AppendChar(key.KeyChar);
            Console.Write("*");
        } else {
            if (key.Key == ConsoleKey.Backspace && pass.Length > 0) {
                pass.RemoveAt(pass.Length - 1);
                Console.Write("\b \b");
            }
        }
    }
    // Stops Receving Keys Once Enter is Pressed
    while (key.Key != ConsoleKey.Enter);
    return pass;
}