At 8:53 AM 4/10/96, Hal is rumored to have typed:
Peter - didn't they say that the checking station is also listening to the satellites? That way they can tell that you are playing back signals that you taped earlier because they won't match what the satellites are broadcasting right now.
There is going to be processing and network delay involved here (unless Denning et al have figured out some way to communicate faster than the speed of light), so drift between the what you report and what the checking station and repeaters are hearing _at that time_ is inevitable. This is the loophole which allows Peter's attack, a loophole which cannot be closed (because the spoofer can always claim to be on a slower link than she really is and there is nothing the verifiyer can do to prove otherwise.) If I want to pretend to be closer to the receiver than my true location I simulate a slow link which gives me enough time to record what the signals would be at the near location and then quickly resend them to give the appearance of the spoofed location. In fact, I think that this really all boils down to trying to use GPS as a non-interactive proof of location, and the information posted about the system does not address the obvious attacks on such systems which are known from research into ZNPs.
If their authenticated repeaters are used then you have to assume the checking station has all the satellite signals and again the best you can do is pretend to be a Mole Man.
The authenticated repeaters may collect all signals, _but the receiving station does not get them all at once_ because it will take time for the signals to propogate from the repeater back to the station attempting to determine location. Having all of the signals does not help the checking station other than allowing it to share a set of sats with the person attempting to authenticate. It still does not And perhaps more importantly, do you really want anyone you connect to on the net to know your location to the nearest 10 meters? What is Dennings fascination with building Big Brother? jim