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Comment by tgsovlerkhgsel | Hacker News Reader

> My bet is that in space there would be a noticable increase in heat/energy if they did encryption by default.

Why would it? The data originates from earth, and should be encrypted during the uplink leg too, so the crypto should all happen in the ground segment (or even well before it reached anything that could be considered part of the satellite setup, honestly).

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Satellites have long lifespans and have to outlast current crypto algorithms. Ideally they're nothing more than radio repeaters that rebroadcast the uplink signal.

That seldom works. Simple repeaters transmit the strongest signal they get and can be easily hijacked by a rogue ground transmitter. This is the main reason simple repeaters on orbit went out of fashion in the 1980s.

Really depends on what the satellite does, and even for purely "dumb pipe" satellites you'll need some telemetry for stationkeeping, repositioning etc.

Practically, you'll also want to be able to reconfigure spot beam to backhaul mappings or even cross-connect some spot beams to cut satphone-to-satphone voice latency in half etc.

That's not even considering constellations like Iridium that do actual packet switching in space.

Correct. That is what almost all geostationary satellites are. If you want encryption, do it at the application layer.

Exactly, and the little bit of data actually destined for satellites – which includes momentum wheel and booster control – is something you’ll definitely want to at least authenticate.

I believe that’s one of the few things that even amateur radio operators are allowed to encrypt for that reason.

The only thing I can think of is maybe the satellite company runs compression on the data. Encryption would prevent that.

They could compress then encrypt before transmitting it over a radio link.

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