| 摘要 |
<p>PURPOSE: To prevent vehicle theft by varying ID code signals for each transmission, and transmitting ID code signals such that the ID code signals to be transmitted the next time cannot be easily anticipated from the ID code signals transmitted. CONSTITUTION: In order for a transmitting part 1 to transmit code signals obtained by encryption of ID codes, the ID codes and rolling codes used in varying the code signals for each transmission are classified into several blocks, the number of times that encryption operations are repeated is determined through an arithmetic process, and bit operations such as substitution exclusive OR and computation of pseudo-random numbers are repeatedly performed. In order for a receiving part 2 to receive and decode the code signals, operations that are inverse with respect to those performed at the transmitting part 1 are performed. Thus encrypted signals are varied for each transmission, anticipating the encrypted signals to be transmitted the next time becomes difficult, and therefore vehicle theft can be prevented.</p> |
