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Authentication method for keyless entry system

  • US 5,506,905 A
  • Filed: 06/10/1994
  • Issued: 04/09/1996
  • Est. Priority Date: 06/10/1994
  • Status: Expired due to Term
First Claim
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1. In a keyless entry system for performing any of a plurality of functions in a protected environment and having a receiver and at least one remote transmitter, the method of encoding a command for transmission to the receiver and for authenticating the command comprising the steps of:

  • installing into each transmitter and the receiver a cryptographic algorithm including a programmable cryptographic key for defining mathematical operations of the algorithm, a transmitter ID and an initial seed code peculiar to each transmitter, and a plurality of function codes;

    in the transmitter;

    selecting a function code for performing a predetermined function,calculating an authenticator code by the algorithm as a function of both the seed code and the function code, andtransmitting the transmitter ID, the function code and the authenticator code to the receiver; and

    in the receiver;

    verifying the transmitter ID by comparing with an ID installed in the receiver;

    then calculating an authenticator code by the algorithm as a function of both the transmitted function code and the seed code; and

    verifying the transmission by comparing the transmitted authenticator code with the receiver calculated authenticator code.

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