Authentication method for keyless entry system
First Claim
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.
3 Assignments
0 Petitions
Accused Products
Abstract
A system for remotely controlling a desired door locking or other function in a vehicle or other protected environment has a transmitter and receiver for communicating a message including a sequence number, the code of a selected function to be performed and an authenticator. An algorithm in the transmitter and in the receiver has a cryptographic key and a seed code. Each algorithm generates the authenticator as a function of both the seed code and the function code; if the authenticators are equal, the message is valid. Upon each transmission the seed code is updated and the sequence number is incremented. The receiver updates its seed code according to the transmitted sequence number to keep the algorithms in synchronism.
-
Citations
13 Claims
-
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, and transmitting 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11)
-
-
8. In a keyless entry system for performing a predetermined function in a protected environment 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 key for defining the algorithm operation, a transmitter ID, a sequence number and an initial seed code peculiar to each transmitter, and a plurality of function codes; in the transmitter; selecting a function code for performing the predetermined function; calculating an authenticator code by the algorithm as a function of both the seed code and the function code; updating the seed code and the sequence number; and transmitting the transmitter ID, the sequence number, 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; if the receiver sequence number corresponding to the verified ID is within a limited number of increments of the transmitted sequence number, updating the seed code corresponding to the transmitted ID and the receiver sequence number until the receiver sequence number matches the transmitted sequence number; then calculating an authenticator code by the algorithm as a function of both the transmitted function code and the updated seed code; and verifying the transmission by comparing the transmitted authenticator code with the receiver calculated authenticator code. - View Dependent Claims (9)
-
-
12. In a keyless entry system having a remote transmitter for commanding any of a plurality of functions in a protected environment and a receiver for responding to the commands and carrying out the commanded function, a secure communication method carried out by a cryptographic algorithm in both the transmitter and receiver for generating an authenticator code, wherein each algorithm includes a working register and means for incrementing the register with input data to produce an authenticator output and working register feedback;
- the communication method comprising the steps of;
incorporating into the transmitter and the receiver a cryptographic key for determining the mathematical operations of the algorithm, a transmitter ID, and an initial register state for the working register, a function code for each function, and integers y and z; in the transmitter; a) determining a function code for performing the commanded function; b) loading the working register with the register state; c) modulo-2 adding the function code to the working register feedback bit-by-bit and incrementing the working register for each function code bit; d) incrementing the working register y times; e) incrementing the working register z times and reading the authenticator output; f) transmitting a message including the transmitter ID, the function code and the authenticator code; and
in the receiver;g) verifying the ID by comparing with an ID stored in the receiver; h) executing steps a through e using the received function code, and the receiver register state to generate a receiver authenticator code; and verifying the transmission by comparing the transmitted authenticator code with the receiver authenticator code. - View Dependent Claims (13)
- the communication method comprising the steps of;
Specification