Method and apparatus for encoding security status information

• US 7,600,038 B2
• Filed: 12/04/2003
• Issued: 10/06/2009
• Est. Priority Date: 12/04/2002
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Certicom Corporation (Blackberry Limited)
• Inventors: Struik, Marinus
• Primary Examiner(s): Srivastava; Vivek
• Assistant Examiner(s): CHOUDHURY, AZIZUL Q
• Application Number:
  US10/726,493
• Publication Number:
  US 20040136527A1
• Time in Patent Office: 2,133 Days
• Field of Search: 713/190, 709/236, 710/30
• US Class Current: 709/236
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/0435 wherein the sending and receiving network entities apply symmetric encryption, i.e. same key used for encryption and decryption cryptographic mechanisms or cryptographic arrangements for symmetric key encryption H04L9/06
• CPC Class Codes: H04L 63/06 for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• CPC Class Codes: H04L 67/04 specially adapted for terminals or networks with limited capabilities; specially adapted for terminal portability
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04W 12/02 Protecting privacy or anonymity, e.g. protecting personally identifiable information [PII]
• CPC Class Codes: H04W 12/033 of the user plane, e.g. user's traffic
• CPC Class Codes: H04W 12/04 Key management, e.g. using generic bootstrapping architecture [GBA]
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 28/06 Optimizing the usage of the radio link, e.g. header compression, information sizing , discarding information system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others

Abstract

A method of transmitting messages from a sender to a recipient over a wireless channel, the messages including a sequence counter and a frame counter. The method comprises establishing initial values of the sequence counter and the frame counter at the sender. Initial values of the frame counter and the sequence counter are provided to the recipient. The sender sends compressed messages including the value of the sequence counter and not the frame counter and monitors for an acknowledgement of receipt by the recipient. When no acknowledgment is received, the sender sends uncompressed messages until an acknowledgement of receipt is received from the recipient. The sequence counter is incremented and the next value of the frame counter is established as the integer next larger than previous value of the frame counter which is congruent to the sequence counter modulo 256.

Claims

1. A method of transmitting a frame counter value from a first correspondent to a second correspondent in a data communication system, said first correspondent having a frame counter for generating said frame counter value, and said first correspondent further having a sequence counter for generating a sequence counter value, said frame counter value and said sequence counter value being stored in memory;

said method comprising steps being performed by said first correspondent and comprising;

transferring said frame counter value and said sequence counter value from said memory into a processing unit;

calculating in said processing unit a compressed representation of said frame counter value by removing from said frame counter value a component equal to said sequence counter value; and

generating and transmitting a message over a communication link to said second correspondent in said data communication system, said message comprising said sequence counter value and said compressed representation of said frame counter value;

whereby upon receipt of said message by said second correspondent, said second correspondent may uniquely recover said frame counter value from said sequence counter value and said compressed representation of said frame counter value in said message.

2. The method according to claim 1 wherein said sequence counter updates said sequence counter value subsequent to the transmission of a message.

3. The method according to claim 2 wherein said sequence counter updates said sequence counter value by:

(a) transferring said sequence counter value from said memory into a processing unit;

(b) incrementing said sequence counter value in said processing unit in a direction of counting; and

(c) replacing said sequence counter value stored in said memory with said incremented sequence counter value.

4. The method according to claim 2 wherein said frame counter updates said frame counter value by:

(a) transferring said frame counter value and said sequence counter value from said memory into a processing unit;

(b) calculating in said processing unit a next value in a direction of counting from said frame counter value that is congruent to the sequence counter value modulo the size of the sequence counter; and

(c) replacing said frame counter value stored in said memory with said calculated next value.

5. The method according to claim 4 wherein the size of the sequence counter is 256.

6. The method according to claim 1 wherein said frame counter value is used by at least one of said first and second correspondents in a cryptographic operation.

7. The method according to claim 6 wherein said sequence counter value is used by said first correspondent for matching said message with an acknowledgement of said message sent from said second correspondent.

8. The method according to claim 1 wherein said frame counter value is uniquely recoverable from said message by concatenating said compressed representation of said frame counter value and said sequence counter value.

9. The method according to claim 8 wherein said compressed representation of said frame counter value is three bytes in length.

10. A method of transmitting frame counter values from a first correspondent to a second correspondent in a data communication system, said first correspondent having a frame counter for generating said frame counter values, and said first correspondent further having a sequence counter for generating sequence counter values, said method comprising steps being performed by said first correspondent and comprising:

transmitting over a communication link to said second correspondent in said data system an initial frame counter value and an initial sequence counter value;

subsequently generating and transmitting messages to said second correspondent, each of said messages comprising a sequence counter value, but not a frame counter value;

whereby upon receipt of each of said messages by said second correspondent, said second correspondent may recover said frame counter value from said sequence counter value in said message and from a previously stored frame counter value;

periodically generating and transmitting to said second correspondent a message comprising both a frame counter value and a sequence counter value, the periodicity being defined by a predefined criteria.

11. The method according to claim 10 wherein said sequence counter updates said sequence counter value subsequent to the transmission of a message.

12. The method according to claim 11 wherein said sequence counter updates said sequence counter value by:

(a) transferring said sequence counter value from memory into a processing unit;

(b) incrementing sad sequence counter value in said processing unit in a direction of counting; and

(c) replacing said sequence counter value in said memory with said incremented sequence counter value.

13. The method according to claim 11 wherein said frame counter updates said frame counter value by:

(a) transferring said frame counter value and said sequence counter value from memory into a processing unit;

(b) calculating in said processing unit a next value in a direction of counting from said frame counter value that is congruent to the sequence counter value modulo the size of the sequence counter; and

(c) replacing said frame counter value in said memory with said calculated next value.

14. The method according to claim 13 wherein the size of the sequence counter is 256.

15. The method according to claim 10 wherein at least one of said frame counter values is used by at least one of said first and second correspondents in a cryptographic operation.

16. The method according to claim 15 wherein said sequence counter values are used by said first correspondent for matching said message with an acknowledgement of said message sent from said second correspondent.

17. The method according to claim 10 wherein said predefined criteria are when a predetermined number of said messages comprising a sequence counter value, but not a frame counter value, are transmitted by said first correspondent.

18. The method according to claim 17 wherein said predetermined number is in the range 2 to 10.

19. The method according to claim 10 wherein said first correspondent monitors for an acknowledgement of receipt of said messages by said second correspondent, and said predefined criteria are when no acknowledgement is received.