On Thu, 22 Nov 2001, Roy M. Silvernail wrote:
Using a GPS coordinate set as keying material? Hope it's just
Given that a GPS receiver gets ephemeris data, almanach data and pseudorandom code from each currently visible sat it has probably to do with the latter. Consider S/A (which may or may not be switched off now, I haven't checked): if you've got a secret part of the key you can refine your position despite deliberate degradation (selective availability) than the party without the key.
additional keying material. Knowing the intended destination of something like a movie in transit to a theater seems pretty easy, and the set of GPS coordinates encompassing your average multiplex would seem to be pretty small compared to the usual keyspaces discussed here.