Consider the following security measures for airline travel. A list of names of people who are not allowed to fly is maintained by the government and given to the airlines; people whose names are on the list are not allowed to make flight reservations. Before entering the departure area of the airport, passengers go through a security check where they have to present a government-issued ID and a boarding pass. Before boarding a flight, passengers must present a boarding pass, which is scanned to verify the reservation. Show how someone who is on the no-fly list can manage to fly provided that boarding passes could be generated online (as an HTML page) and then printed. Please provide a step-by-step description of the attack. Which additional security measures should be implemented in order to eliminate this vulnerability?

HINT: remember that airplane-boarding passes contain a simple two-dimensional barcode