public class MyCustomUserNameValidator : UserNamePasswordValidator
{
    // This method validates users. It allows two users, test1 and test2 
    // with passwords 1tset and 2tset respectively.
    // This code is for illustration purposes only and 
    // MUST NOT be used in a production environment because it is NOT secure.	
    public override void Validate(string userName, string password)
    {
        if (null == userName || null == password)
        {
            throw new ArgumentNullException();
        }

        if (!(userName == "test1" && password == "1tset") && !(userName == "test2" && password == "2tset"))
        {
            throw new SecurityTokenException("Unknown Username or Password");
        }
    }
}