On Sun, 21 Dec 2003 12:42:11 GMT, Fred J. McCall
wrote:

pervect wrote:



Well, if you assume the enemy has magical powers (which is essentially
what you're doing above), then I suppose anything is possible. Just
by the way, even your "black box" replacement above isn't simple.
Examine the replacement of PPS-SM by SAASM, for example.

You know, if you want to keep speculating, you might want to learn a
bit of something about the GPS system before you continue. See
http://gps.losangeles.af.mil/user/pr...curity/hae.htm for a
very brief synopsis on GPS security.

Another poster already pointed me at

http://www.globalsecurity.org/milita...nd-gps_faq.pdf

which was much better, IMO.

From my POV, the key point that I missed in my earlier post (the one
you just replied to, there have been a bunch since then) is that GPS
is spread spectrum.

Of course this has spawned yet another argument, where I point out
that if you know what the satellites are supposed to be sending, use
of encryption (rather than spread spectrum) would be unlikely to
provide much security. Other people have suggested that "good codes"
are harder to break than this. I haven't gotten around yet to
pointing out that all you'd have to do given that you would already
have the plaintext because you know what the satellites have to be
sending is to broadcast a signal that would provide a "lookup table".
Then someone else could point out that this would slow the response
time of the GPS system down. Then I could say, yes, but is that
really significant. And the argument could go on for quite some
time....