Integrated remote keyless entry and ignition disabling system for vehicles, using updated and interdependent cryptographic codes for security

摘要

A remote-control unit for vehicles in which an immobilizer facility and keyless entry facility are united to enable bidirectional transmission. Further, a cost reduction is achieved by decreasing the number of parts, and labor required for maintenance is diminished. A remote-control unit for vehicles includes a circuit 16 for receiving a cryptographic code CR from a vehicle when a key 10 is fitted into a key cylinder 21, a circuit 17 for storing a cryptographic code, a control circuit for producing a first cipher system code CS1 in response to a cryptographic code, and producing a second cipher system code CS2 in response to actuation of a manual switch 12, and a transmission circuit 15 for transmitting the cipher system codes in the form of radio waves to the vehicle. The first cipher system code contains a command for permitting engine start for the vehicle, and the second cipher system code is produced on the basis of a cryptographic code in the memory circuit and contains a command for closing or opening the door lock of the vehicle.