SCALABLE REPLAY COUNTERS FOR NETWORK SECURITY

• US 20130283347A1
• Filed: 04/20/2012
• Published: 10/24/2013
• Est. Priority Date: 04/20/2012
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Hui, Jonathan W., Hong, Wei, Ahuja, Anjum, Kondaka, Krishna
• Granted Patent: US 9,077,772 B2
• Time in Patent Office: Days
• US Class Current: 726/3
• CPC Class Codes: H04L 63/0846 using time-dependent-passwords, e.g. periodically changing passwords
• 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 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

In one embodiment, an authenticator in a communication network maintains a persistent authenticator epoch value that increments each time the authenticator restarts. The authenticator also maintains a persistent per-supplicant value for each supplicant of the authenticator, each per-supplicant value set to a current value of the authenticator epoch value each time the corresponding supplicant establishes a new security association with the authenticator. To communicate messages from the authenticator to a particular supplicant, each message uses a per-supplicant replay counter having a security association epoch counter and a message counter specific to the particular supplicant. In particular, the security association epoch counter for each message is set as a difference between the authenticator epoch value and the per-supplicant value for the particular supplicant when the message is communicated, while the message counter is incremented for each message communicated.

Claims

1. A method, comprising:

maintaining, at an authenticator in a communication network, a persistent authenticator epoch value that the authenticator increments each time the authenticator restarts;

maintaining, at the authenticator, a persistent per-supplicant value for each supplicant of the authenticator, each per-supplicant value set to a current value of the authenticator epoch value each time the corresponding supplicant establishes a new security association with the authenticator; and

communicating at least one message from the authenticator to a particular supplicant, each message comprising a per-supplicant replay counter having a security association epoch counter and a message counter specific to the particular supplicant, wherein the security association epoch counter for each message is set as a difference between the authenticator epoch value and the per-supplicant value for the particular supplicant when the message is communicated, and wherein the message counter is is incremented for each message communicated.

2. The method as in claim 1, wherein maintaining the authenticator epoch value comprises, in response to starting the authenticator:

reading the persistent authenticator epoch value from a non-volatile memory;

incrementing the authenticator epoch value; and

storing the incremented authenticator epoch value in the non-volatile memory.

3. The method as in claim 1, further comprising, in response to the authenticator being restarted:

incrementing the authenticator epoch value; and

communicating, by the authenticator, a next message to the particular supplicant with the security association epoch counter set to the difference between the incremented authenticator epoch value and the per-supplicant value for the particular supplicant, and the message counter reset to zero.

4. The method as in claim 1, wherein maintaining the persistent per-supplicant value for each supplicant comprises:

storing each persistent per-supplicant value with a corresponding pairwise temporal key (PTK) stored during each new security association.

5. The method as in claim 1, further comprising:

incrementing the security association epoch counter for the particular supplicant in response to the message counter rolling over.

6. The method as in claim 1, further comprising:

establishing a new security association with the particular supplicant in response to the security association epoch counter rolling over.

7. The method as in claim 1, wherein the replay counter is eight bytes, and wherein the security association epoch counter is four bytes, and wherein the message counter is four bytes.

8. The method as in claim 1, wherein the authenticator is a field area router (FAR).

9. The method as in claim 1, further comprising:

establishing the new security association with each supplicant using a 4-way handshake.

10. The method as in claim 1, wherein there is no difference between the authenticator epoch value and the per-supplicant value for the particular supplicant in response to establishing a new security association with the particular supplicant, and wherein the security association epoch counter is set to zero when there is no difference between the authenticator epoch value and the per-supplicant value.

11. An apparatus, comprising:

one or more network interfaces to communicate with a shared-media communication network;

a processor coupled to the network interfaces and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process, when executed by the apparatus as an authenticator, operable to;

maintain a persistent authenticator epoch value that increments each time the authenticator restarts;

maintain a persistent per-supplicant value for each supplicant of the authenticator, each per-supplicant value set to a current value of the authenticator epoch value each time the corresponding supplicant establishes a new security association with the authenticator; and

communicate at least one message to a particular supplicant, each message using a per-supplicant replay counter having a security association epoch counter and a message counter specific to the particular supplicant, wherein the security association epoch counter for each message is set as a difference between the authenticator epoch value and the per-supplicant value for the particular supplicant when the message is communicated, and wherein the message counter is incremented for each message communicated.

12. The apparatus as in claim 11, wherein the process when executed to maintain the authenticator epoch value is further operable to, in response to starting the authenticator:

read the persistent authenticator epoch value from a non-volatile memory;

increment the authenticator epoch value; and

store the incremented authenticator epoch value in the non-volatile memory.

13. The apparatus as in claim 11, wherein the process when executed is further operable to, in response to the authenticator being restarted:

increment the authenticator epoch value; and

communicate a next message to the particular supplicant with the security association epoch counter set to the difference between the incremented authenticator epoch value and the per-supplicant value for the particular supplicant and the message counter reset to zero.

14. The apparatus as in claim 11, wherein the process when executed to maintain the persistent per-supplicant value for each supplicant is further operable to:

store each persistent per-supplicant value with a corresponding pairwise temporal key (PTK) stored during each new security association.

15. The apparatus as in claim 11, wherein the process when executed is further operable to:

increment the security association epoch counter for the particular supplicant in response to the message counter rolling over.

16. The apparatus as in claim 11, wherein the process when executed is further operable to:

establish a new security association with the particular supplicant in response to the security association epoch counter rolling over.

17. The apparatus as in claim 11, wherein the replay counter is eight bytes, and wherein the security association epoch counter is four bytes, and wherein the message counter is four bytes.

18. The apparatus as in claim 11, wherein the apparatus is a field area router (FAR).

19. The apparatus as in claim 11, wherein the process when executed is further operable to:

establish the new security association with each supplicant using a 4-way handshake.

20. A tangible, non-transitory, computer-readable media having software encoded thereon, the software, when executed by a processor on an authenticator in a computer network, operable to:

maintain a persistent authenticator epoch value that increments each time the authenticator restarts;

maintain a persistent per-supplicant value for each supplicant of the authenticator, each per-supplicant value set to a current value of the authenticator epoch value each time the corresponding supplicant establishes a new security association with the authenticator; and

communicate at least one message to a particular supplicant, each message using a per-supplicant replay counter having a security association epoch counter and a message counter specific to the particular supplicant, wherein the security association epoch counter for each message is set as a difference between the authenticator epoch value and the per-supplicant value for the particular supplicant when the message is communicated, and wherein the message counter is incremented for each message communicated.