Secret key programming technique for transponders using encryption

• US 20060214766A1
• Filed: 03/28/2005
• Published: 09/28/2006
• Est. Priority Date: 03/28/2005
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Ghabra, Riad, Singh, Gurpreet
• Granted Patent: US 7,327,216 B2
• Time in Patent Office: Days
• US Class Current: 340/5.250
• CPC Class Codes: G07C 2009/00388 code verification carried out according to the challenge/response method
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2009/00865 remotely by wireless communication
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A secret key is programmed into a key transponder from a base station wherein the key transponder stores a fixed ID, a first default key segment stored in a first memory page, and a second default key segment stored in a second memory page. The secret key comprises a first new secret key segment to be stored in the first memory page of the key transponder and a second new secret key segment to be stored in the second memory page of the key transponder. A mutual authentication process is initially conducted using the default key. Write commands are sent to the key transponder in transferring each key segment. Write acknowledgement signals and confirmatory reading back of the data are employed for ensuring proper storage of the secret key. Recovery from the most probable types of errors enables successful programming of key transponders in an efficient manner with a low loss rate.

Claims

1. A method of programming a secret key into a key transponder from a base station, wherein said key transponder stores a fixed ID, a first default key segment stored in a first memory page, and a second default key segment stored in a second memory page, and wherein said secret key comprises a first new secret key segment to be stored in said first memory page of said key transponder and a second new secret key segment to be stored in said second memory page of said key transponder, said method comprising the steps of:

conducting a mutual authentication process using a first default key segment and a second default key segment;

sending a first write command identifying said first memory page;

checking for a first acknowledgement signal from said key transponder;

if said first acknowledgement signal is not detected, then returning to said step of conducting a mutual authentication process using said first default key segment and said second default key segment;

if said first acknowledgement signal is detected, then sending a first read command identifying said first memory page;

if no read data is detected in response to said first read command, then returning to said step of conducting a mutual authentication process using said first default key segment and said second default key segment;

if correct read data is detected in response to said first read command, then sending a second write command identifying said second memory page;

checking for a second acknowledgement signal from said key transponder;

if said second acknowledgement signal is not detected, then conducting a mutual authentication process using said first new secret key segment and said second default key segment and returning to said step of sending a second write command;

if said second acknowledgement signal is detected, then sending a second read command identifying said second memory page;

if no read data is detected in response to said second read command, then returning to said step of conducting a mutual authentication process using said first new secret key segment and said second default key segment;

if correct read data is detected in response to said second read command, then said base station associating said fixed ID of said key transponder with said first and second new secret key segments.

2. The method of claim 1 further comprising the steps of:

sending said first new key segment to said key transponder in response to said first acknowledgement signal and prior to said first read command; and

sending said second new key segment to said key transponder in response to said second acknowledgement signal and prior to said second read command.

3. The method of claim 1 further comprising the step of:

if incorrect data is detected in response to said first read command, then returning to said step of sending said first write command.

4. The method of claim 3 further comprising the step of:

if incorrect data is detected in response to said second read command, then returning to said step of sending said second write command.

5. The method of claim 4 wherein communication between said base station and said key transponder is encrypted using rolling encryption after said mutual authentication process, said method further comprising the steps of:

updating said rolling encryption prior to returning to said step of sending said first write command; and

updating said rolling encryption prior to returning to said step of sending said second write command.

6. The method of claim 1 further comprising the step of:

if incorrect data is detected in response to said first read command, then conducting a mutual authentication process using said first new secret key segment and said second default key segment before sending said second write command.

7. The method of claim 1 further comprising the step of:

if incorrect data is detected in response to said second read command, then conducting a mutual authentication process using said first new secret key segment and said second new secret key segment and then returning to said step of sending said second write command.

8. A base station for programming a secret key into a key transponder, wherein said key transponder stores a fixed ID, a first default key segment stored in a first memory page, and a second default key segment stored in a second memory page, and wherein said secret key comprises a first new secret key segment to be stored in said first memory page of said key transponder and a second new secret key segment to be stored in said second memory page of said key transponder, said base station comprising:

a transceiver for wirelessly communicating with said key transponder; and

a controller programmed to perform the steps of;

conducting a mutual authentication process using a first default key segment and a second default key segment;

sending a first write command identifying said first memory page;

checking for a first acknowledgement signal from said key transponder;

if said first acknowledgement signal is not detected, then returning to said step of conducting a mutual authentication process using said first default key segment and said second default key segment;

if said first acknowledgement signal is detected, then sending a first read command identifying said first memory page;

if no read data is detected in response to said first read command, then returning to said step of conducting a mutual authentication process using said first default key segment and said second default key segment;

if correct read data is detected in response to said first read command, then sending a second write command identifying said second memory page;

checking for a second acknowledgement signal from said key transponder;

if said second acknowledgement signal is not detected, then conducting a mutual authentication process using said first new secret key segment and said second default key segment and returning to said step of sending a second write command;

if said second acknowledgement signal is detected, then sending a second read command identifying said second memory page;

if no read data is detected in response to said second read command, then returning to said step of conducting a mutual authentication process using said first new secret key segment and said second default key segment;

if correct read data is detected in response to said second read command, then said base station associating said fixed ID of said key transponder with said first and second new secret key segments.

9. The base station of claim 8 wherein said controller is further programmed to perform the steps of:

sending said first new key segment to said key transponder in response to said first acknowledgement signal and prior to said first read command; and

sending said second new key segment to said key transponder in response to said second acknowledgement signal and prior to said second read command.

10. The base station of claim 8 wherein said controller is further programmed to perform the step of:

if incorrect data is detected in response to said first read command, then returning to said step of sending said first write command.

11. The base station of claim 10 wherein said controller is further programmed to perform the step of:

if incorrect data is detected in response to said second read command, then returning to said step of sending said second write command.

12. The base station of claim 11 wherein communication between said base station and said key transponder is encrypted using rolling encryption after said mutual authentication process, and wherein said controller is further programmed to perform the steps of:

updating said rolling encryption prior to returning to said step of sending said first write command; and

updating said rolling encryption prior to returning to said step of sending said second write command.

13. The base station of claim 8 wherein said controller is further programmed to perform the step of:

if incorrect data is detected in response to said first read command, then conducting a mutual authentication process using said first new secret key segment and said second default key segment before sending said second write command.

14. The base station of claim 8 wherein said controller is further programmed to perform the step of:

if incorrect data is detected in response to said second read command, then conducting a mutual authentication process using said first new secret key segment and said second new secret key segment and then returning to said step of sending said second write command.

15. A method of programming a secret key into a key transponder from a base station, wherein said key transponder stores a fixed ID, a first default key segment stored in a first memory page, and a second default key segment stored in a second memory page, and wherein said secret key comprises a first new secret key segment to be stored in said first memory page of said key transponder and a second new secret key segment to be stored in said second memory page of said key transponder, said method comprising the steps of:

conducting a mutual authentication process using a first default key segment and a second default key segment;

sending a first write command identifying said first memory page;

checking for a first acknowledgement signal from said key transponder;

if said first acknowledgement signal is not detected, then returning to said step of conducting a mutual authentication process using said first default key segment and said second default key segment;

if said first acknowledgement signal is detected, then sending a first read command identifying said first memory page;

if no read data is detected in response to said first read command, then returning to said step of conducting a mutual authentication process using said first default key segment and said second default key segment;

if any return data is detected in response to said first read command, then sending a second write command identifying said second memory page;

checking for a second acknowledgement signal from said key transponder;

if said second acknowledgement signal is not detected, then conducting a mutual authentication process using said first new secret key segment and said second default key segment and returning to said step of sending a second write command;

if said second acknowledgement signal is detected, then sending a second read command identifying said second memory page;

if no read data is detected in response to said second read command, then returning to said step of conducting a mutual authentication process using said first new secret key segment and said second default key segment;

if any return data is detected in response to said second read command, then conducting said mutual authentication process using said first and second new secret key segments and if successful then said base station associating said fixed ID of said key transponder with said first and second new secret key segments.