FasTrak is a passive system relative to the transponder -- it uses the transponder ID, a vehicle sensor, and an axle counter to generate toll records. The associated license plate capture-and-decode feature is only invoked if a non-transponder-equipped or invalidated-transponder-equipped vehicle attempts to use a transponder-controlled lane or toll booth. Its primary purpose is to provide sufficient information for a CHP officer to stop the offending vehicle. The original FasTrak design couldn't handle an invalidated transponder: it assumed that all correctly-formatted responses were from valid devices.
Most of the automated toll systems were designed in an era of expensive processing and centralized databases: if the toll collection point can generate a formatted record that can be subsequently processed for billing purposes, that was sufficient functionality. Social engineering of automated toll systems may have already arrived: as long as the dollar amounts of the abuse lie within the noise factor of the victim's bill (e.g., a limousine service or a trucking company) the issue of retrofitting encryption to provide 'sufficient protection' will not be raised. Elliott --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
