Patent ID: 7423353

Claim:
A vehicle anti-theft system comprising: an engine and a vehicle side device installed on a vehicle; an engine control device and a manually operable switch connected to said vehicle side device; a plurality of units including a steering locking section connected to said vehicle side device; and a portable device that is possessed by a driver of said vehicle; said vehicle side device comprising: a vehicle side transmitter receiver for performing two-way communications between said vehicle side device and said portable device; a vehicle side storage circuit that stores a verification code for said portable device; and a vehicle side control circuit that is connected to said vehicle side transmitter receiver, said vehicle side storage circuit and said switch; said portable device comprising: a portable device side transmitter receiver for performing two-way communications between said portable device and said vehicle side device; a portable device side storage circuit that stores an inherent encrypted code corresponding to said vehicle; and a portable device side control circuit that is connected to said portable device side transmitter receiver and said portable device side storage circuit; wherein said vehicle side control circuit and said vehicle side transmitter receiver send a query signal containing said verification code to said portable device side transmitter receiver in response to an operation signal of said switch; said portable device side control circuit and said portable device side transmitter receiver receive said signal sent from said vehicle side device thereby to read said encrypted code from said portable device side storage circuit, and at the same time to send an answer signal containing said encrypted code corresponding to said query signal to said vehicle side transmitter receiver; when said answer signal corresponds to said query signal, said vehicle side control circuit unlocks said steering locking section and at the same time permits starting of said engine; said engine control device and said plurality of units are provided with microprocessor units installed thereon, respectively; said respective microprocessor units of said engine control device and said plurality of units have common data between themselves and said vehicle side device; and said vehicle side control circuit compares the common data that is possessed by itself and the common data that is stored in said respective microprocessor units with each other, and unlocks said steering locking section and at the same time outputs a signal to permit starting of said engine to said engine control device when both of said common data coincide with each other.