"Attacks on ADS-B can be inexpensive and highly successful.
Apart from short term disruption what would be achieved ?
There will never be anything published on what can be done (even currently) in these regards.
EDIT:
Akro, Oz...yes, WAAS is still subject to RAIM.
Sarcs,
Crucially, the latter platform provides enough bandwidth to enable encryption,
Yes and no. It is the broadcast string length that is the formost issue, there is not room in the string to add encription, so it would have to be a seperate string, (OR perhaps use ADS-C which is only somewhat better.)
Second is the bandwidth issue, which as it is already overloaded, adding encription would effectively double the congestion and associated drops of ac..