Keyless entry system using a rolling code

• US 5,600,324 A
• Filed: 02/29/1996
• Issued: 02/04/1997
• Est. Priority Date: 05/11/1992
• Status: Expired due to Fees

• Current Assignee: Meritor Light Vehicle Technology, LLC (Meritor, Inc. (Nevada))
• Original Assignee: Rockwell International Corporation
• Inventors: Chen, Xuemin, Yin, Xiaowei, Reed, Irving S.
• Primary Examiner(s): Swarthout, Brent A.
• Assistant Examiner(s): HILL, ANDREW M
• Application Number:
  US08/609,093
• Time in Patent Office: 341 Days
• Field of Search: 341/176, 340/825.2, 340/825.3, 340/825.31, 340/825.34, 340/825.69, 340/825.72, 340/825.56, 361/171, 361/172, 70/278, 380/43
• US Class Current: 341/176
• CPC Class Codes: G07C 2009/00253 dynamically, e.g. variable code - rolling code
• CPC Class Codes: G07C 2009/00769 with data transmission performed by wireless means
• CPC Class Codes: G07C 2209/06 Involving synchronization or resynchronization between transmitter and receiver; reordering of codes
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: G07C 9/00817 where the code of the lock can be programmed
• CPC Class Codes: H04L 2209/84 Vehicles
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/3228 One-time or temporary data, i.e. information which is sent for every authentication or authorization, e.g. one-time-password, one-time-token or one-time-key

Abstract

A keyless entry system which employs an identification code for each transmitter, a key sequence number, and a rolling code generated by a polynomial equation ensure unauthorized access. The system provides for resynchronization in the event of battery replacement or power failure. The system accommodates activation of a transmitter and incrementation of the rolling code when it is out of range of the receiver. This system further accommodates replacement of lost or stolen keys with a higher priority key, which then prevents access by the lost or stolen transmitter.

Claims

1. A method for programming transmitters for use in conjunction with a receiver for authenticating said transmitters, wherein each of said transmitters transmits a message signal to said receiver when activated, said message signal including a transmitter identification number field, a transmitter rolling code state number field, and a transmitter clock counter field, said method comprising the steps of:

assigning unique transmitter identification codes to each of at least one transmitters;

placing said receiver in learning mode;

sequentially activating each transmitter and thereby sending said message signal to said receiver;

receiving said message signal at said receiver;

storing, in corresponding registers within said receiver, said identification number, rolling code state and clock counter for each of said transmitters; and

removing said receiver from said learning mode and placing said receiver in normal operation mode.

2. A method for assigning unique identification codes to a family of transmitters used in conjunction with a receiver, and for registering each transmitter of said family of transmitters with said receiver, and for registering a replacement transmitter in place of one of said transmitters, said method comprising the steps of:

(a) assigning unique identification codes to each transmitter in said family of transmitters by;

(i) sequentially assigning an ordinal number to each said transmitter, and

(ii) assigning a key number to each said transmitter;

(b) registering each said transmitter of said family of transmitters with said receiver by;

(i) storing, in corresponding registers within said receiver in concatenated fashion within each said register, said ordinal number and said key number for each transmitter; and

(c) registering a replacement transmitter in place of one of said transmitters by;

(i) assigning an ordinal number to said replacement transmitter identical to said assigned ordinal number of said transmitter being replaced,

(ii) assigning a key number to said replacement transmitter which is greater in value than said key number of said transmitter being replaced, and

(iii) storing, in said corresponding register within said receiver, said replacement transmitter key number in concatenated fashion with said pre-existing stored ordinal number.

3. A method for providing secure remote actuation of a vehicle door locking and unlocking mechanism employing a remote transmitter and a receiver, wherein said receiver issues a lock/unlock command to said locking and unlocking mechanism only after having authenticated a lock/unlock request from said transmitter, said transmitter having a unique transmitter identification number, a first rolling code generator, a rolling code state counter, a clock counter, and signal producing means for producing a message signal having fields for said identification number, a rolling code generated by said first rolling code generator, and said rolling code state counter value, and said receiver having a second rolling code generator, said method comprising the steps of:

(a) storing in said receiver said identification number, said rolling code state counter value and said clock counter value for each authorized transmitter during a learning mode;

(b) generating said rolling code within said transmitter using said transmitter rolling code state counter value;

(c) transmitting said transmitter identification number, said generated rolling code, and said rolling code state counter value from said transmitter to said receiver as said message signal;

(d) incrementing said transmitter clock counter;

(e) incrementing said rolling code state counter;

(f) receiving said message signal at said receiver;

(g) comparing said transmitter identification number with said stored authorized identification number, and proceeding if said received transmitter identification number matches one of said stored authorized identification numbers;

(h) comparing said received transmitted rolling code state counter value to said stored rolling code state counter value and

(i) if said received value exceeds said stored value, increasing said stored value to match said received value,

(ii) if said received value matches said stored value, leaving said stored value unchanged;

(i) generating a rolling code within said receiver said stored rolling code state counter value;

(j) comparing said received transmitter rolling code to said generated receiver rolling code; and

(k) issuing said lock/unlock command only if said transmitter and receiver rolling codes match.

4. A method for providing unique transmitter identification numbers, for programming a receiver to recognize authorized transmitters, and for providing secure remote actuation of a vehicle door locking and unlocking mechanism employing a remote transmitter and a receiver, wherein said receiver issues a lock/unlock command to said locking and unlocking mechanism only after having authenticated a lock/unlock request from said transmitter, said transmitter having a unique transmitter identification number, a first rolling code generator, a rolling code state counter, a clock counter, and signal producing means for producing a message signal having fields for said identification number, a rolling code generated by said first rolling code generator, and said rolling code state counter value, and said receiver having a second rolling code generator, said method comprising the steps of:

(a) assigning unique transmitter identification numbers to each transmitter in a family of authorized transmitters by;

(1) sequentially assigning an ordinal number to each said transmitter, and

(2) assigning a key number to each transmitter;

(b) programming said receiver to recognize each said transmitter in said family of authorized transmitters by

(1) placing said receiver in a learning mode,

(2) sequentially activating each transmitter to transmit its identification number, its rolling code state counter value and its clock counter value to said receiver,

(3) storing, in corresponding registers, said identification number, said rolling code state counter value and said clock counter value for each said transmitter, and

(4) removing said receiver from said learning mode and placing said receiver in a normal mode of operation; and

(c) authenticating a lock/unlock request from a transmitter by;

(1) generating said rolling code within said transmitter using said transmitter rolling code state counter value;

(2) transmitting said transmitter identification number, said generated rolling code, and said rolling code state counter value from said transmitter to said receiver as said message signal;

(3) incrementing said transmitter clock counter;

(4) incrementing said rolling code state counter;

(5) receiving said message signal at said receiver;

(6) comparing said transmitter identification number with said stored authorized identification number, and proceeding if said received transmitter key number matches one of said stored authorized identification numbers;

(7) comparing said received transmitted rolling code state counter value to said stored rolling code state counter value and

(i) if said received value exceeds said stored value, increasing said stored value to match said received value,

(ii) if said received value matches said stored value, leaving said stored value unchanged;

(8) generating a rolling code within said receiver said stored rolling code state counter value;

(9) comparing said received transmitter rolling code to said generated receiver rolling code; and

(10) issuing said lock/unlock command only if said transmitter and receiver rolling codes match.