The part they kept out of the headline:
> for use in distributing the keys for accessing the military GPS signals
It’s common knowledge that the military has access to a separate, encrypted, higher-precision GPS signal. “Numbers station” implies that they’re distributing unrelated encrypted information, but they’re not; it’s not surprising that GPS signals would be used to deliver information related to GPS, even if only military receivers have any use for it!
That's not it, though. This is available on the consumer L1 band, and you can even read that info using a $5 Ublox receiver (UBX-RXM-SFRBX command).
The most militarily-valuable aspect of the military GPS signals is actually the anti-spoofing qualities, rather than the higher precision. Survey-grade GPS gear has been able to achieve centimetre-level precision from the regular civilian signals for several years now, using RF fuckery like tracking the phase angle and other techniques.
To be sure, you want the precision too. NATO countries have M982 Excalibur GPS-guided artillery rounds that are precise enough that you can select not just the building you want to hit but the specific window you want the round to enter.
But the primary benefit of the encrypted signal is that it provides cryptographic assurance that the signal is not spoofed and one can be confident that one's GPS-guided cruise missile or other munition is not being diverted off-course.
Nowadays the military GPS signal has moved from transmitting the legacy "P(Y) code", which is a Cold War-era design, to the "M code" which incorporates several decades' worth of lessons learned in terms of spoofing resistance, cryptographic authentication, etc. It's actually a really neat rabbit hole to climb down.
The source data and analytical code (in Julia) is also available at https://lsc-pagepro.mydigitalpublication.com/publication/?i=...
In my view people nitpicking the 404 media story are being ridiculous. Everyone in their audience knows GPS originated as a military system, indeed I think most of teh general public knows that. Bashing them for not mentioning this is just looking for something to be mad about.
Here, it appears to be a rekeying system for specialized military gear.
I didn't want to imply that regular people could simply inject data into what's emitted by GPS satellites.
Sorry if that wasn't clear, but I am aware that GPS is operated by the US military.
Where the article loses me is the implication that this is somehow sinister or beyond the pale: it's just piggybacking on a global transmitter network that exists anyway, why not?
Well, you could look at it that way, or you could say that the fact that it's broadcasting all the time is the steganography. That constant transmission of nonsense that nobody wants is what makes it fail to be suspicious when you send a message that somebody does want.
We don't know that it's a key that's being sent. For all we know, it could be just random data. Obviously it's most likely not random data, but ciphertext. Either way, we have no idea what the message is.
PDF of article (page 62) https://cdn.coverstand.com/61061/865273/2c88ea662e2b57478723...
What's interesting to me is how out of date US GPS system is compared to China's BeiDou
and while most US GPS receivers will use Russia's GLONOSS, China's BeiDou is blocked
Theory is that Russia is constantly practicing to totally disrupt GPS and GNSS (and the Chinese system) across all of Europe.
https://www.scientificamerican.com/article/how-to-see-stars-...
It wasn't. It was going to be a military-only system, until KAL007 presented the obvious life-saving civilian case.
But yes, the title of this article might as well read "Satellite system developed for military use is being used for a military purpose."