Denning's Geo-crypto

[Eugene Leitl]

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.