Forzar una respuesta correcta por consola

C#

//Ver: https://stackoverflow.com/questions/37359161/how-would-i-make-a-yes-no-prompt-in-console-using-c

bool confirmed = false;
string Key;
do {
    Console.Write("Please enter a login key: ");
    Key = Console.ReadLine();
    Console.WriteLine("You entered, " + Key + " as your login key!");

    ConsoleKey response;
    do
    {
        Console.Write("Are you sure you want to choose this as your login key? [y/n] ");
        response = Console.ReadKey(false).Key;   // true is intercept key (dont show), false is show
        if (response != ConsoleKey.Enter)
            Console.WriteLine();

    } while (response != ConsoleKey.Y && response != ConsoleKey.N);

    confirmed = response == ConsoleKey.Y;
} while (!confirmed);
Console.WriteLine("You chose {0}!", Key);
Console.ReadLine();

Muestra de ejecución:

Please enter a login key: potato
You entered, potato as your login key!
Are you sure you want to choose this as your login key? [y/n] a
Are you sure you want to choose this as your login key? [y/n] s
Are you sure you want to choose this as your login key? [y/n] l
Are you sure you want to choose this as your login key? [y/n] d
Are you sure you want to choose this as your login key? [y/n] k
Are you sure you want to choose this as your login key? [y/n] f
Are you sure you want to choose this as your login key? [y/n] d
Are you sure you want to choose this as your login key? [y/n] n
Please enter a login key: banana
You entered, banana as your login key!
Are you sure you want to choose this as your login key? [y/n] y
You chose banana!