Location-based System Delivers User Authentication Breakthrough

By Dorothy E. Denning and Peter F. MacDoran

Nice april fools article... After all, position information is nothing more than a particular phase shift (time delay) between GPS data streams received from the set of satellites overhead. If I report the datastreams received -- or information about them -- then someone can calculate where I am. (Indeed, there are GPS applications where the device whose position is of interest doesn't actually decode the GPS data, it merely reports what it receives to some central data collection site, where the arithmetic is done.) If I want to pretend to be somewhere else, all I have to do is some simple geometry to calculate the time delays I want to report, and then phase-shift the GPS streams from their received position to where they would be at the other place. Note that relying on the PP code (military code) in the GPS stream is no help, since I don't need to be able to interpret the PP stream in order to pretend to be elsewhere, I merely need to know where I am and where I want to be, to insert the right phase shift. paul !----------------------------------------------------------------------- ! Paul Koning, NI1D, C-24183 ! 3Com Corporation, 1-3A, 118 Turnpike Road, Southborough MA 01772 USA ! phone: +1 508 229 1695, fax: +1 508 490 5873 ! email: paul_koning@isd.3com.com or paul_koning@3mail.3com.com ! Pgp: 27 81 A9 73 A6 0B B3 BE 18 A3 BF DD 1A 59 51 75 !----------------------------------------------------------------------- ! "Be wary of strong drink. It can make you shoot at tax collectors ! -- and miss!" ! -- Robert A. Heinlein, "The Notebooks of Lazarus Long" ! in "Time Enough for Love"