if your potential adversary is a five eyes nation state intelligence agency with the ability to sniff traffic from 10/100/200GbE submarine fiber DWDM links, the fact that spacex/starlink is also a US company and subject to national security letters and other monitoring won't help you.

Likely wouldn't help even if it wasn't Five Eyes.

At some point, the communication has to enter the terrestrial network. That entry node is likely to be under the influence, if not outright control, of Five Eyes security infrastructure.

You would need to build out a lot of infrastructure to escape the sort of ubiquitous surveillance that is available to those organizations.

> At some point, the communication has to enter the terrestrial network.

Not necessarily. If you're communicating between two SpaceX terminals, that could feasibly avoid SpaceX ground stations. I don't know how capable SpaceX's routing actually is to know if this is within their scope though.

and then we come back to one of the original missions of the NSA, which was to intercept international telephone call/data/telex traffic that had no terrestrial intermediary, between two different C or Ku band geostationary earth stations in two different locations of the world which were using a geostationary transponder as a relay point.

If it's flying through the air and somebody really wants to grab it they will, whether they can read it depends on how good your crypto is.

https://en.wikipedia.org/wiki/RAF_Menwith_Hill

Can’t anyone (well, anyone with state kind of money) observe the laser and at least dump it with perfect accuracy to keep for later decryption? I’d think tapping n undersea cable is more work than observing light going from sat to sat? I’m just spitballing here, I have no idea what’s possible or not but I’d be curious to know.

> Can’t anyone (well, anyone with state kind of money) observe the laser

LEO is far from a true vacuum. But it's sparse enough that you have limited beam scattering. Getting a read on a sat-to-sat laser emission from the ground is nontrivial.

What about scatter from the satellite itself? The laser can't be perfectly absorbed on the receiving end. I haven't done the calculations, but I fully expect the spot size is much larger than the receiver.

That said, I imagine that for any serious bandwidth, you won't get enough SNR to decode anything from the ground.

Remember that the only reason a laser works for this kind of link is that it is very highly collimated. The light scattering from the receiving satellite is diffuse so the intensity will go down very quickly with distance. It might be observable with a suitably large telescope, but I doubt it would be practical.

So you have a reflection off random bits of equipment followed by a trip through most of earths atmosphere? That doesn't sound easy at all - and they could choose wavelengths that won't make the trip well if at all.

I guess if you got an observation platform up closer that would help.

More like farther away. Put a spy satellite in a high orbit like traditional satellite internet and it'll be able to see half of Starlink simultaneously with essentially no distortion.

If they were strongly encrypted there may be no reason for a nation state to observe the intersatellite links, but I wouldn't expect this at least for the near future since Elon's focus will probably be to cut corners to get the absolute best performance possible.

If it is encrypted and you drop just a couple bits due to noise you can't read it.

There are multiple layers of encoding to mitigate this. CCSDS [0] is very widely used for satellite communications, and a Google image search for CCSDS protocols [1] will give you a quick view of the protocol stack (which can vary a lot as different CCSDS protocols are used in different applications).

[0] https://en.wikipedia.org/wiki/Consultative_Committee_for_Spa...

[1] https://www.google.com/search?q=ccsds+protocols&source=lnms&...

Edited to add: I'm not making any claims on what protocols Starlink uses specifically. Just describing the general approach.

I think it would require someone to fly a spy sat up near one of the SpaceX sats. From the ground the atmosphere would attenuate the signal too badly and you'd only have visibility for a few minutes at a time as it passes overhead maybe.

In practical terms I don't think it's a major concern. Much more likely that the spy agencies would tap the lines coming out of the ground stations.

> Much more likely that the spy agencies would tap the lines coming out of the ground stations

Which is a significant step backwards for e.g. Russia.

Currently, all data between Asia and North America runs on cables. Anybody can spy on those. If those data did satellite laser hops, only those with ground stations would have access. Everyone else gets locked out.

The company I work for changed its internal routing of data to use encryption for 100% of traffic crossing the public internet. I have to think everyone else is doing this as well. Is spying on cables like this even useful? How would ay usable data be extracted?

You can learn a lot from the metadata and packet size/timing.

Military inter-satellite links deliberately choose laser wavelengths that do not propagate well through Earth's atmosphere. Such links could only be intercepted from a space-borne platform. I have no idea what laser wavelength StarLink is using, so it may not apply here.

I have no doubt that (like every other geo-mobile satellite constellation) the system allows for "port mirroring" on point-to-point links, or (more likely) relays everything through a ground station even when doing so has performance implications. This allows them to fulfill their obligation to government(s) surveillance.

If you wanted to do this, it's probably a lot easier to intercept the RF to the ground stations.