It seems that the GPS protocol is just too simple, and lacks proper security elements.
An article linked by the article contains an informative section "How GNSS spoofing works", [1]. Excerpt:
> Effectively, if you can transmit to a GPS receiver, you can speak GPS to it and it will trust you. There's no authentication process involved, and you might even be able to MacGyver together a working spoofing device out of a hacked $15 USB-to-VGA adapter. Granted, you could easily wind up with thousands of dollars in fines or even prison time for trying it—but in strictly technical terms, there's very little stopping you.
Yeah the civilian signal has no cipher / integrity-checking. The military signals do have those (and it chirps at 10x the rate of the civilian signal).
Oh absolutely they do. That's why they reserve the right to turn off the civilian signals in an extreme time of war.
In reality would that happen? Probably not. There are multiple GNSS constellations these days, so just denying GPS is probably not a safe bet (you can buy civilian uBlox chips for $<50 that are tri-band...)
I love reading about the military aspect of GPS. It is really fascinating the use-cases they plan for. Hopefully they never actually are used in such an extreme scenario.
An article linked by the article contains an informative section "How GNSS spoofing works", [1]. Excerpt:
> Effectively, if you can transmit to a GPS receiver, you can speak GPS to it and it will trust you. There's no authentication process involved, and you might even be able to MacGyver together a working spoofing device out of a hacked $15 USB-to-VGA adapter. Granted, you could easily wind up with thousands of dollars in fines or even prison time for trying it—but in strictly technical terms, there's very little stopping you.
[1] https://arstechnica.com/cars/2019/06/claims-of-tesla-hack-wi...