From: IN%"hfinney@shell.portal.com" "Hal" 11-APR-1996 18:06:18.51
The method of using authenticated devices which provide timestamped data from satellites not visible to the authenticating site does not need to provide that data in real time. Even if it is delayed so it comes in later than the data from the remote site, the verifying site can still use it to calculate what the remote site should have been seeing, and so get the benefit of using timings from all the satellites visible to the remote site (again, assuming the remote site itself has a low latency connection to the authenticating site).
In regards to these timestamping devices... how do they know the correct time? It looks like that would be distortable, and with that, you could simply simulate the satellites to them via placing the device inside a metal box and piping in the appropriately modified signals. If it's getting its time information from the signals themselves, things get even easier. -Allen