[time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon
cjaysharp at gmail.com
Mon Aug 14 13:12:19 EDT 2017
I guess it would depend on the level of infrastructure available to the
attacker, clock distribution is a reasonably well solved problem isn't it?
There would, I suppose also be the issue of receiver swamping, you could
monitor received signal levels as it's my understanding that the signals
from the satellites are weak enough that they're indiscernible from noise
floor without some rather complex processing?
Authentication via signing could be another feasible way to prevent
spoofing except we are potentially talking about interference from state
actors who may even be the very people who run one of the satellite networks
On 14 Aug 2017 5:51 pm, "Attila Kinali" <attila at kinali.ch> wrote:
> 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
> > 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
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