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[–]postnapoleoniceurope 11 points12 points  (3 children)

Fundamentally though, your idea is just a variant on trusted hardware: what's to stop the probe from secretly transmitting back the private key? You might as well just make a secure box that delays the transmission of every message by a few hours.

Of course, there is also the practical problem that communications with probes in the Oort cloud take antenna dishes tens of meters in diameter...

[–]AusIV 2 points3 points  (2 children)

Security is never a boolean value, only about degrees of confidence. You can have a fairly high degree of confidence that a device you've designed, built, and always had in your possession will never transmit it's private key. But that degree of confidence drops dramatically once the device has been in someone else's possession. If a malicious individual gained possession of the physical device, I would no longer trust it to delay transmission or keep its private key protected.

However if the device were nearly a light year away, you could have a fairly high degree of confidence that nobody has reached the device to tamper with it (and you could adjust this confidence interval as space travel technology proliferates). If you are satisfied that reaching the device for purposes of tampering isn't feasible, you only need confidence in the device's design and construction rather than its ability to prevent an entity with physical possession from altering its behavior.

[–]postnapoleoniceurope 2 points3 points  (0 children)

Ah, that's a good point, I missed the fact that we are talking about a device that you yourself launched. However, that still limits it to entities with enough resources to launch such a probe, in a world where few other entities have the capability to do so. After all, they can always launch another probe, chasing yours, and have that probe tamper with your probe.

It's still the case that simply burying the device deep in the ground in a non-seismicly active area, and using a seismic sensor to detect someone trying to tunnel to the device, would usually be simpler. You could leverage existing technology to drill ultra-deep holes, as well as the technology to backfill them with concrete. I'd also argue observing that process from start to finish is probably a lot easier. You can also still use the light-speed minimum trick if you really want, albeit with a much large number of encryption operations.

[–]Natanael_LTrusted third party 0 points1 point  (0 children)

Aliens. :P