One-way key fob and vehicle pairing verification, retention, and revocation

• US 9,698,980 B2
• Filed: 04/04/2016
• Issued: 07/04/2017
• Est. Priority Date: 08/30/2012
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ho, Jin-Meng
• Primary Examiner(s): Armouche, Hadi
• Assistant Examiner(s): Khan, Sher A
• Application Number:
  US15/090,125
• Publication Number:
  US 20160218870A1
• Time in Patent Office: 456 Days
• CPC Class Codes: B60R 25/10 actuating a signalling device
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G07C 9/20 involving the use of a pass
• CPC Class Codes: H04L 2209/84 Vehicles
• CPC Class Codes: H04L 9/0827 involving distinctive intermediate devices or communication paths network architectures or network communication protocols using different networks H04L63/18
• CPC Class Codes: H04L 9/0861 Generation of secret information including derivation or calculation of cryptographic keys or passwords
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage
• CPC Class Codes: H04L 9/3226 using a predetermined code, e.g. password, passphrase or PIN network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083
• CPC Class Codes: H04L 9/3268 using certificate validation, registration, distribution or revocation, e.g. certificate revocation list [CRL]

Abstract

Embodiments of the invention provide methods for key fob to control unit verification, retention, and revocation. After an initial pairing between a key fob and a control unit, the devices share a secret operation key (OpKey). For verification, the key fob sends the 8 lowest-order bits of a 128-bit counter and some bits of an AES-128, OpKey encrypted value of the counter to the control unit. For key revocation and retention, the control unit is prompted to enter an OpKey retention and revocation mode. Subsequently, each of the remaining or new key fobs is prompted by the user to send a verification message to the control unit. When the control unit is prompted to exit the OpKey retention and revocation mode, it retains the OpKeys of only the key fobs that sent a valid verification message immediately before entering and exiting the OpKey retention and revocation mode.

Claims

1. A key fob device, comprising:

a transmitter configured to transmit signals to a control unit;

a memory configured to store a key fob counter and an operation key (OpKey); and

a processor coupled to the transmitter and memory, the processor configured to;

generate an AES-128 OpKey-encrypted value of the key fob counter;

transmit to the control unit a message including a predetermined number of lowest-order bits of the key fob counter and a predetermined number of bits of the AES-128 OpKey-encrypted value of the key fob counter;

transmit to the control unit a command to enter a revocation mode, wherein OpKeys associated with key fob devices that operate during a revocation mode period following entering the revocation mode are retained by the control unit and all other OpKeys associated with key fob devices that do not perform an operation during the revocation mode period are deleted from the control unit.

2. The key fob device of claim 1, wherein the predetermined number of lowest-order bits of the key fob counter is 8 bits.

3. The key fob device of claim 1, wherein the key fob counter is a 128-bit counter.

4. The key fob device of claim 1, wherein the processor is configured to:

increment the key fob counter by one after transmitting the message to the control unit.

5. The key fob device of claim 1, wherein the key fob device is configured not to receive transmissions from the control unit.

6. A control unit device, comprising:

a receiver configured to receive signals from a key fob device;

a memory configured to store a control unit counter and at least one operation key (OpKey); and

a processor coupled to the receiver and the memory, the processor configured to;

receive, from the key fob, a message including a predetermined number of bits of an AES-128 OpKey-encrypted value of a key fob counter of the key fob device, the AES-128 OpKey-encrypted value of the key fob counter being encrypted using an OpKey associated with the key fob device;

generate an AES-128 OpKey-encrypted value of the control unit counter using the OpKey associated with the key fob device;

verify whether or not the predetermined number of bits of the AES-128 OpKey-encrypted value of the key fob counter matches the predetermined number of corresponding bits from the AES-128 OpKey-encrypted value of the control unit counter; and

enter a revocation mode in response to receiving a revocation command, wherein, during a revocation mode period following entering the revocation mode, the control unit determines OpKeys that are associated with key fob devices that perform an operation with the control unit during the revocation mode period, determines OpKeys that are associated with key fob devices that do not perform an operation with the control unit during the revocation mode period, retains the OpKeys associated with the key fob devices that perform an operation with the control unit during the revocation mode period, and deletes the OpKeys associated with the key fob devices that do not perform an operation with the control unit during the revocation mode period.

7. The control unit device of claim 6, wherein the processor is configured to:

receive, from the key fob device, a chosen number of lowest-order bits of the key fob counter; and

update the control unit counter based on the received bits before generating the AES-128 OpKey-encrypted value of the control unit counter.

8. The control unit device of claim 7, wherein the chosen number of lowest-order bits of the control unit counter is 8 bits.

9. The control unit device of claim 6, wherein the processor is configured to:

initiate a control operation when the predetermined number of bits of the AES-128 OpKey-encrypted value of the key fob counter matches the predetermined number of corresponding bits from the AES-128 OpKey-encrypted value of the control unit counter.

10. The control unit device of claim 6, wherein the control unit counter is a 128-bit counter.

11. The control unit device of claim 7, wherein the processor is configured to:

restore the control unit counter to a value before the update after failing to verify that the predetermined number of bits of the AES-128 OpKey-encrypted value of the key fob counter matches the predetermined number of corresponding bits from the AES-128 OpKey-encrypted value of the control unit counter.

12. The control unit device of claim 6, wherein the message further includes a data field that identifies a command to be executed by the control unit.

13. The control unit device of claim 6, wherein the revocation mode period continues for a predetermined period of time after entering the revocation mode.

14. The control unit device of claim 6, wherein the revocation mode period ends upon receiving a command from the key fob device to exit the revocation mode.

15. The control unit device of claim 6, wherein the revocation command is received from the key fob device.