Patent ID: 6658328
Filing Date: 2003-12-02
Classification: G07C

Abstract:
A passive function control system for a vehicle comprising:a vehicle based transceiver for transmitting a challenge signal, the vehicle based transceiver including a first controller, a random number generator, a first encryption key, and a first memory for storing an identification code, the first controller providing the challenge signal having a random number from the random number generator and the identification code from the memory, the first controller encrypting at least a portion of the random number and at least a portion of the identification code of the challenge signal using the first encryption key; and a portable transceiver for receiving the challenge signal and for transmitting a challenge response signal, the portable transceiver comprising a second controller, a second memory for storing a reference identification code, and a decryption key corresponding to the first encryption key of the vehicle based transceiver, the second controller decrypting the encrypted portions of the challenge signal using the decryption key, comparing the identification code to the reference identification code, and outputting the challenge response signal, having the random number, only in response to identification code comparison indicating a match, the first controller responding to the challenge response signal when the random number of the challenge response signal is related to the random number from the random number generator.