Patent ID: 6847286

Claim:
A method for authenticating a spare vehicle key to be used with a vehicle in the absence of a regular key, the method comprising the acts of: providing the spare vehicle key with an identification number prior to requesting authentication of the spare key; transmitting a random number generated by the key and the key identification number to the vehicle; transmitting the random number generated by the key to a central station with an identification number of the vehicle from a source other than the vehicle; transmitting the random number generated by the key from the central station to the vehicle using an encoding associated with the vehicle identification number; comparing the random number generated by the key received from the central station with the random number generated by the key received from the key by the vehicle; transmitting the key identification number to the central station from the vehicle if the key random numbers match; checking the transmitted key identification number by the central station; and authenticating the spare vehicle key and sending an authorization signal from the central station to the vehicle.