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Abstract

An encryption process for a rolling code of a remote keyless entry system. The encryption process makes use of a command code shift register, a security code shift register, and a sequence code shift register in which the contents of these registers is transmitted from a portable transmitter to a receiver associated with the vehicle in order to perform a desirable function. The command code shift register provides the code of the function to be performed and the sequence code shift register provides a sequence code for updating the sequence of the receiver. The security code shift register includes a security code which is updated by a first and second pseudo random number generator after each transmission. Each of two pseudo random number generators include associated shift registers and exclusive NOR gates such that a first bit location and a tap bit location of each of the shift registers are exclusively NORed to provide a first bit location in the shift register. A series of the bit locations of the first and second shift registers are exclusively ORed together to set the bits of the security code register.

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First Claim