METHOD TO PROVIDE WARNING TO RELAY ATTACKS ON KEYLESS ENTRY AND START SYSTEMS

A method and apparatus are presented for authenticating a vehicle equipped with a passive keyless entry and start system. The method includes sending a request for unlock or ignition start from the key fob to a vehicle's network access device (NAD), sending a first challenge signal from the NAD to the key fob, determining if the key fob is within range of the NAD, sending a second challenge signal from the NAD to the mobile device, determining if the mobile device is within range of the NAD, and sending a warning to the mobile device when the key fob or mobile device is not within range of the NAD.