ADSB is a small data payload and a CRC check on the end. That's it. (
https://mode-s.org/decode/adsb/introduction.html)
There is no signature that can be verified (I can say I am anyone in the sky and you can't tell if I am telling you the truth)
There is no point to point encryption (I can listen to anyone's traffic and interject as I see fit with the obvious problems that would cause)
ADSB at its very core is an extremely insecure protocol essentially depending on your (the pilots) participation simply because you are told to do so.
Every single transponder with ADSB out capability has the ability to change its own configuration. You (the pilot) could
illegally change the type designation and Mode S output, the proceed to bust any airspace you like all the while (mostly) showing up as someone else's aircraft. This is very illegal. But, it sure does limit the suggestion that ADSB is somehow beneficial for
security.
Better yet, GPS positional data is and open format (with a variety of formats supported by most). It is quite simple to feed bogus GPS data to a transponder. Ground stations would be able to determine this anomaly, but air-to-air would not. A spoofed target could report at any altitude and as any type of aircraft and from the air, you would not be able to tell what is real and what is not. This exact thing has been demonstrated with consumer drones fitted with cheap ADSB-out chipsets.
https://www.ainonline.com/aviation-...ads-b-insecure-and-easily-spoofed-say-hackers
All of this said, I do not dislike ADSB. I think the implementation is garbage (but fixable), the privacy implications horrible (yet fixable), however find it most concerning there is the notion we should take it on the chin and just be happy
they still let us fly...
The reasons there are such severe consequences for turning off your ADSB output is because that is the only control
they have left over you. The tech itself is easily defeated.