| > Inspired by the TOR network. Because it has such high delays? Basically revealing the information which the onion service or exit node encrypted for you only after, potentially, a few trips around the globe? That makes me think this can be achieved without spacecraft, by just having geographically distributed private keys (even just a few kilometers; you just need the light delays to dominate over processing delays). And I don't think you need more than two keys: if you wrap it in A(B(A(B(message)))), then party B cannot work on the first layer but first needs to send it to A, party A cannot decrypt the second layer but first needs to sent it back to B, etc. One of the parties could be your recipient, so that would also work with an expensive one-off spacecraft. > land on the surface a distant body in the solar system landing is a lot more difficult than staying in Neptune's orbit (notice how many moon-bound spacecraft crashed, even only in recent years!); you'll get the same characteristics by just going out to a desired orbit. Also note that the amount of delay between Earth and <your orbit, such as Neptune's> will vary wildly |
The problem that arise is (and which is solved by the spacecraft to Neptune) is that with any earth based system, someone could secretly move copies of both ends closer together, secretly, and decrypt the lock faster than expected. Putting a spacecraft on a trajectory with no realistic chance of ever coming back makes this possibility impossible (as long as the layers of keys are encrypted only when the spacecraft arrived at its destination. Even if the delay between earth and neptune vary wildly, it is predictable, and any local system could piggyback a larger scale system like this for safety