Though it is encouraging to see Mr. Fowler raising this concern, unfortunately the described countermeasure is not sufficient to prevent such an attack. Well-motivated attackers can be willing to get themselves infected to legally obtain an authorization code. Similarly, it is not unlikely that a black market for such codes would develop.
In the absence of a more secure technology (which, by the way, is available), a much safer solution would be to discontinue notifications for the weeks leading to Election Day.
Rosario Gennaro, Adam Krellenstein and James Krellenstein, New York
The writers are cryptoscientists.