5 ms·

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 tappin

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.

jandrese 6y ago
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.
- JumpCrisscross 6y ago
  > 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.
  - sfblah 6y ago
    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?
    - jandrese 6y ago
      You can learn a lot from the metadata and packet size/timing.
JumpCrisscross 6y ago
> 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.
- bob33212 6y ago
  If it is encrypted and you drop just a couple bits due to noise you can't read it.
  - jsrcout 6y ago
    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_Space_Data_Systems https://en.wikipedia.org/wiki/Consultative_Committee_for_Spa... [1] https://www.google.com/search?q=ccsds+protocols&source=lnms&tbm=isch 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.
- TeMPOraL 6y ago
  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.
  - ska 6y ago
    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.
anonymousiam 6y ago
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.
lutorm 6y ago
If you wanted to do this, it's probably a lot easier to intercept the RF to the ground stations.

jandrese 6y ago

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.

JumpCrisscross 6y ago
> 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.
- sfblah 6y ago
  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?
  - jandrese 6y ago
    You can learn a lot from the metadata and packet size/timing.

JumpCrisscross 6y ago

> 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.

bob33212 6y ago
If it is encrypted and you drop just a couple bits due to noise you can't read it.
- jsrcout 6y ago
  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_Space_Data_Systems https://en.wikipedia.org/wiki/Consultative_Committee_for_Spa... [1] https://www.google.com/search?q=ccsds+protocols&source=lnms&tbm=isch 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.
TeMPOraL 6y ago
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.
- ska 6y ago
  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.

anonymousiam 6y ago

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.

lutorm 6y ago

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