CBS's "60 Minutes" had a "Oooh Scarey" segment about the Global Positioning System last Sunday. The scarey part is, according to 60 Minutes, that any old terrorist government can now put together accurate guided missles and wreak death and destruction upon our homeland. The crux of the problem is that the system broadcasts out positioning information to one and all indiscriminately, and according to the show there's no way we can stop it. Because my mind is regularly exposed to wild conspiracy theories and all sorts of crazed paranoiac ravings (i.e., I read Usenet), I started thinking that this is rather unlikely. I speculated that the government may in fact have designed the satellite systems so that they could be told to do several things in case of national emergency: * Shut down (probably possible; they may have actually mentioned this on the show). Problem is that lots of friendlies may grow to rely on the data for life-critical things, like guiding commercial airliners. * Shut down normal transmission and begin strongly encrypted transmission. No mention of this; apparently, the satellites were originally designed with some sort of weak system that made the data difficult to use for high-accuracy purposes, but that's been defeated (by the FAA or someone contracted thereto). * Enter into a bogus-cleartext with encrypted subchannel mode, where the plaintext is slyly made to be wrong, but using some subchannel encrypted "good stuff" is still available. I don't know much about how this system works, so I don't know whether any of my thoughts are relevant. It's probably most likely that the government indeed blasted these things up into space without considering using encryption technology to enhance security. -- Mike McNally : m5@tivoli.com : Day Laborer : Tivoli Systems : Austin, TX ------------------------------------------------------------------------ Remember that all experimentation does not produce extrapolated results. - k. pisichko