[time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Attila Kinali]

On Mon, 14 Aug 2017 12:09:43 -0400
Tim Shoppa <tshoppa at gmail.com> wrote:

> I think if you are only trying to spoof a single receiver it would be
> possible to walk a spoofed time/space code in a way that time moved without
> so obvious of a discontinuity. I'm sure there would be effects a time-nut
> could notice still.

Not really. Unless you have a multi-antenna setup (see jim's email),
you have nothing to compare the signal to. Even an ideal reference
clock in your GPS receiver does not help, as the attacker could be
tracking you in such a way that you will never see a discontinuity
in time or position and that all the other sanity checks you do
still don't show anything.

With a two antenna setup, you can already check whether the phases
add up to what you expect them to be, given your position relative
to the satellites position. You do not need 3 antennas as a potential
attacker can spoof the phase of some satellites correctly, but not
of all at the same time. This at least gives you a spoof/no-spoof signal.

With an antenna array you can do some masking of spoofers (ie placing
a null where the spoofer comes from). But this increases the cost and
complexity of the system super-linear with the number of antennas.
Maybe one way to do it, would be to use a single receiver with a stable
reference clock and switch between antennas in short succession. Ie similar
to how the early single channel GPS receivers worked, but for antennas
instead of SVs. But I have no idea how easy/difficult this would be
to do and how well it would work against spoofers.

				Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson