4 ms·
I do know the basics of GPS but not much further than this. Wouldn't it be possible to embed a clock in a GPS receiver that gets used when decrypting the packe
by chockchocschoir 5y ago
I do know the basics of GPS but not much further than this.
Wouldn't it be possible to embed a clock in a GPS receiver that gets used when decrypting the packets it receives? So instead of just receiving a encrypted packet and trusting it, it'll decrypt it and check when the message was from and if the slew is more than ~1 minute or whatever, then it is probably forged.
That would at least prevent the scenario that you're describing, but since I don't know enough about GPS, it probably introduces other problems.
- kevincox 5y agoSure it's possible but GPS is all about time. Faking the time by a fraction of a second will break the whole protocol. 1min is enough to transport the signed packets across the world. Sky basically if your only authentication scheme is time, and the protocol is all about getting the time, it is very hard to detect proxing from other locations because the bound of accepted times basically needs to be big enough that you can be spoofed a meaningful amount.
- moltke 5y agoThe clock slew is how GPS works in the first place. You'd have nothing to compare it to.
- sobriquet9 5y agoGPS receiver does not know exact time. It has a built-in clock, but that clock is not very precise and is only used to speed up signal acquisition. The exact time is determined from the received signals. GPS receiver can determine its own position (and get exact time in the process) even after internal clock battery dies, or when internal clock drifts too much. Such cold start takes longer, but is possible.