There was an article in _Scientific American_ February 1996 about GPS. I couldn't find the magazine, but they had this squib on the www.sciam.com website: ‘The Global Positioning System’ Thomas A. Herring Two dozen satellites hovering thousands of miles up can locate your position on the earth's surface to within a few centimeters. Originally constructed for military applications, this network of space beacons today finds civilian applications--such as landing airplanes in fog--that demand accuracy beyond what its designers had thought would be technically possible. According to the website, there was also a letter in the June 1996 issue responding to Herring’s article. Here it is: MILITARY ADVANTAGE I was pleased when I first saw your February article "The Global Positioning System," by Thomas A. Herring. As developers and operators of GPS, we in the Department of Defense and our partners in industry are justifiably proud of the technology. GPS represents the best of American scientific and technical ingenuity as well as being an excellent example of cooperation between the military and civilian sectors. But after reading the entire article, I was disappointed by its unbalanced discussion of the national security aspects of GPS. Yes, the Defense Department does operate GPS with unpopular security features. But these features were not designed to inconvenience the peaceful users of the system, as Herring implies. Rather they were designed to provide U.S. and allied forces with a crucial military edge. Furthermore, the Defense Department is well aware that the security aspects of GPS are an additional burden for many users. And while we believe such measures are still needed at this time to help preserve our military advantage, we have set a goal of discontinuing regular use of the feature known as Selective Availability, the component that degrades GPS accuracy, within a decade. Both time and resources are needed to replace the advantages Selective Availability provides. In light of the revolutionary contributions of GPS to both military and commercial enterprise, Herring could have portrayed the technology in a more evenhanded manner. PAUL G. KAMINSKI Under Secretary Department of Defense -- end of quoted material -- The article, as I recall, was about ways in which civilian users have found, or are finding, ways around the built-in inaccuarcy of the GPS. I don't recall whether crypto was mentioned in the article. My recollection of it was that they had been diddling with the timers or the clock signal or something, as opposed to encrypting anything. But then again it has been a while, and my memory of it isn't too clear. I seem to remember another crypto scheme discussed here at length about GPS, based on a paper by Dr. Dorothy [?] Denning, which involved having the intended recipient's coordinates - which were somehow involved in the encryption. The coordinates are in 3-D. Spheres centered on three of the GPS satellites intersect within a very small space. -- public service announcement: ------------------------------------------------------------- To remove yourself from the cypherpunks mailing list send to: majordomo@toad.com a message that contains the text: unsubscribe cypherpunks in the body of the message, not the subject line. --------------------------------------------------------------