Public Class MyCustomUserNameValidator
    Inherits 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 Overrides Sub Validate(ByVal userName As String, ByVal password As String)
        If Nothing = userName OrElse Nothing = password Then
            Throw New ArgumentNullException()
        End If

        If Not (userName = "test1" AndAlso password = "1tset") AndAlso Not (userName = "test2" AndAlso password = "2tset") Then
            Throw New SecurityTokenException("Unknown Username or Password")
        End If

    End Sub 'Validate
End Class 'MyCustomUserNameValidator

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");
        }
    }
}