Wireless device and method for rekeying with reduced packet loss for high-throughput wireless communications

• US 8,630,416 B2
• Filed: 12/21/2009
• Issued: 01/14/2014
• Est. Priority Date: 12/21/2009
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Qi, Emily H., Walker, Jesse R., Stacey, Robert J., Liondas, Herbert, Jalfon, Marc
• Primary Examiner(s): Rao, Andy
• Assistant Examiner(s): ELAHI, SHAN E
• Application Number:
  US12/643,009
• Publication Number:
  US 20110150223A1
• Time in Patent Office: 1,485 Days
• Field of Search: 380/273, 380277-286, 380 44- 47, 380247-250, 380/270
• US Class Current: 380/273
• CPC Class Codes: H04L 2463/061 applying further key derivation, e.g. deriving traffic keys from a pair-wise master key
• CPC Class Codes: H04L 63/068 using time-dependent keys, e.g. periodically changing keys cryptographic mechanisms or cryptographic arrangements for controlling usage of secret information H04L9/088
• CPC Class Codes: H04L 9/0816 Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04W 12/04 Key management, e.g. using generic bootstrapping architecture [GBA]
• CPC Class Codes: H04W 12/50 Secure pairing of devices
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Embodiments of a wireless device and methods for rekeying with reduced packet loss in a wireless network are generally described herein. In some embodiments, during rekeying operations a new key for reception may be installed early (i.e., prior to receipt of a rekeying confirmation message). The use of the new key for transmission may be delayed until after receipt of the rekeying confirmation message. The early installation of the new key for reception may allow both the new key and old key to be active at the same time for use decrypting received packets to reduce packet loss during rekeying operations. The rekeying confirmation message may be the fourth message of a four-way handshake for rekeying. In some embodiments, two key identifiers may be alternated between four-way handshakes to prevent deletion of the old key.

Claims

1. A method performed by an authenticator for toggling between keys during an established secure communication session with a supplicant, the established secure communication session using a current pair-wise key for unicast communications, the method comprising:

installing a new pair-wise key for reception prior to receipt of a rekeying confirmation message;

continuing to use the current pair-wise key for transmission and delaying use of the new pair-wise key for transmission until after receipt of the rekeying confirmation message,

wherein after installing the new pair-wise key for reception and prior to receipt of the rekeying confirmation message, the method further comprises;

receiving a unicast packet that includes a key ID field, the key ID field including a key ID portion and an Extended Key ID bit, the key ID portion identifying one of a plurality of keys, the Extended Key ID bit indicating whether to toggle between the current pair-wise key and the new pair-wise key;

reading the Extended Key ID bit in the key ID field of the received unicast packet to determine whether to decrypt the received unicast packet using the installed current pair-wise key or the installed new pair-wise key;

continuing to use the current pair-wise key for transmission;

the authenticator installing the new pair-wise key for use in decrypting received packets after receipt of a second message of the four-way handshake and prior to transmission of a third message of the four-way handshake; and

the authenticator delaying use of the new pair-wise key for use in encrypting packets for transmission until after receipt of the fourth message and

wherein the installing is performed by processing circuitry of the authenticator and the current and new pair-wise keys are stored in unicast key ID space of a memory; and

further wherein

the rekeying confirmation message is a fourth message of a four-way handshake for rekeying; and

further wherein

the supplicant is to install the new pair-wise key for reception prior to transmission of the rekeying confirmation message and is to delay using the new pair-wise key for transmission until after the transmission of the rekeying confirmation message; and

further wherein

the supplicant is to delay using the new pair-wise key for transmission until immediately after sending the rekeying confirmation message or a predetermined period of time after sending the rekeying confirmation message; and

further wherein

after installing the new pair-wise key for reception prior to receipt of the rekeying confirmation message, the method includes selecting either the new pair-wise key or the current pair-wise key for decrypting received unicast packets based on a key identifier carried in the received unicast packets; and

further wherein

the supplicant installs the new pair-wise key for use in decrypting received messages after receipt of the third message and prior to transmission of the fourth message, and

wherein the supplicant delays installing the new pair-wise key for use in encrypting packets for transmission until either immediately after transmission of the fourth message or a predetermined period of time after transmission of the fourth message.

2. The method of claim 1 further comprising uninstalling the new pair-wise key if the four-way handshake fails to complete.

3. The method of claim 1 wherein the four-way handshake comprises exchanging Extensible Authentication Protocol over Local area network (EAPOL) Key frames in accordance with an IEEE 802.11 communication standard.

4. The method of claim 1 wherein the rekeying confirmation message is a fourth message of a four-way handshake for rekeying, and

wherein the authenticator comprises memory having unicast key ID space provided therein for two unicast keys for use in communicating unicast traffic, the two unicast keys comprising at least the current pair-wise key and the new pair-wise key.

5. The method of claim 4 further comprising alternating the use of two key identifiers between sequential four-way handshakes to prevent deletion of the current pair-wise key.

6. The method of claim 4 further comprising:

reading the key ID field in a received unicast packet;

identifying either the current pair-wise key or the new pair-wise key from the key ID field; and

using the identified key to decrypt the received unicast packet.

7. The method of claim 6 wherein the memory further includes non-unicast key ID space for one or more non-unicast keys, and

wherein the method further comprises:

determining whether a received packet is either a unicast packet or a non-unicast packet based on a media-access control address of the received packet;

indexing the unicast key ID space based on the key ID field to identify one of the unicast keys when the received packet is determined to be a unicast packet; and

indexing the non-unicast key ID space based on the key ID field to identify one of the non-unicast keys when the received packet is determined to be a non-unicast packet.

8. The method of claim 4 further comprising reading a new-key bit of a received unicast packet to determine whether to switch between keys for decrypting the received unicast packet, wherein the new-key bit is the Extended Key ID bit.

9. The method of claim 4 further comprising performing a four-way handshake to negotiate the new pair-wise key as part of a rekeying operation,

wherein the new pair-wise key is an asymmetric key generated by both the supplicant and the authenticator from information exchanged during the four-way handshake.

10. The method of claim 9 wherein the authenticator is an access point and the supplicant is a mobile station, and

wherein the access point and the mobile station communicate in accordance with an IEEE 802.11 communication standard.

11. A method performed by a supplicant for toggling between keys during an established secure communication session with an authenticator, the established secure communication session using a current pair-wise key for unicast communications, the method comprising:

installing a new pair-wise key for reception prior to transmission of a rekeying confirmation message to the authenticator;

continuing to use the current pair-wise key for transmission and delaying using the new pair-wise key for transmission until after the transmission of the rekeying confirmation message; and

supporting use of both the current pair-wise key for reception and the new pair-wise key for reception after the rekeying confirmation message,

wherein after installing the new pair-wise key for reception and prior to receipt of the rekeying confirmation message, the method further comprises using the current pair-wise key or the new pair-wise key based on a key ID field in a received unicast packet for reception while continuing to use the current pair-wise for transmission, wherein the key ID field includes a key ID portion and an Extended Key ID bit, the key ID portion identifying one of a plurality of keys, the Extended Key ID bit indicating whether to toggle between presently installed keys,

wherein the installing is performed by processing circuitry of the supplicant and the current and new pair-wise keys are stored in unicast key ID space of a memory, and

wherein the method further includes reading the Extended Key ID bit in the key ID field of a received unicast packet to determine whether to toggle between the current pair-wise key and the new pair-wise key to decrypt the received unicast packet.

12. The method of claim 11 wherein the authenticator is to install the new pair-wise key for reception prior to receipt of the rekeying confirmation message, and is to delay use of the new pair-wise key for transmission until after receipt of the rekeying confirmation message, and

wherein both the supplicant and the authenticator continue to support use of the current pair-wise key for reception and the new pair-wise key for reception after the rekeying confirmation message.

13. The method of claim 12 wherein the supplicant continues to support the use of the current pair-wise key for reception and the new pair-wise key for reception until a predetermined period of time after transmission of the rekeying confirmation message, and

wherein the authenticator continues to support the use of the current pair-wise key for reception and the new pair-wise key for reception for a predetermined period of time after receipt of the rekeying confirmation message.

14. The method of claim 11 wherein the supplicant comprises memory having unicast key ID space provided therein for two unicast keys for use in communicating unicast traffic, the two unicast keys comprising at least the current pair-wise key and the new pair-wise key.

15. The method of claim 14 wherein the rekeying confirmation message is a fourth message of a four-way handshake for rekeying, and

wherein the method further comprises alternating use of two key identifiers between sequential four-way handshakes to prevent deletion of the current pair-wise key.

16. A wireless device comprising:

processing circuitry to perform rekeying operations during an established secure communication session which uses a current pair-wise key for unicast communications; and

memory having unicast key ID space to store at least two unicast keys for use in encrypting and decrypting packets comprising unicast traffic,

wherein when the wireless device operates as an authenticator, the processing circuitry is to install a new pair-wise key for reception prior to receipt of a rekeying confirmation message, continue to use the current pair-wise key for transmission, and delay use of the new pair-wise key for transmission until after receipt of the rekeying confirmation message,

wherein when the wireless device operates as an authenticator, the authenticator continues to support the use of the current pair-wise key for reception and the new pair-wise key for reception for a predetermined period of time after receipt of the rekeying confirmation message,

wherein after installing the new pair-wise key for reception and prior to receipt of the rekeying confirmation message, the processing circuitry is configured to use the current pair-wise key or the new pair-wise key based on a key ID field in a received unicast packet for reception while continuing to use the current pair-wise key for transmission,

wherein the key ID field includes a key ID portion and an Extended Key ID bit, the key ID portion identifying one of a plurality of keys, the Extended Key ID bit indicating whether to toggle between presently installed keys, and

wherein the processing circuitry is configured to read the Extended Key ID bit in the key ID field of the received unicast packet to determine whether to toggle between the current pair-wise key and the new pair-wise key to decrypt the received unicast packet.

17. The wireless device of claim 16 wherein when the wireless device operates as a supplicant, the processing circuitry is to install the new pair-wise key for reception prior to transmission of the rekeying confirmation message and is to delay use of the new pair-wise key for transmission until after the transmission of the rekeying confirmation message, and

wherein when the wireless device operates as a supplicant, the supplicant continues to support the use of the current pair-wise key for reception and the new pair-wise key for reception until a predetermined period of time after transmission of the rekeying confirmation message.

18. The wireless device of claim 17 wherein the rekeying confirmation message is a fourth message of a four-way handshake for rekeying, and

wherein the four-way handshake comprises exchanging Extensible Authentication Protocol over Local area network (EAPOL) Key frames in accordance with an IEEE 802.11 communication standard.

19. The wireless device of claim 17 wherein the rekeying confirmation message is a fourth message of a four-way handshake for rekeying, and

wherein the authenticator alternates use of two key identifiers between sequential four-way handshakes to prevent deletion of the current pair-wise key.

20. A method of rekeying performed by a supplicant during a secure video-streaming session that uses a first pair-wise key for unicast communications, the method comprising:

receiving unicast packets that comprise streamed video, the unicast packets being encrypted with the first pair-wise key;

receiving a rekeying initiation message to initiate rekeying operations;

installing a second pair-wise key for reception prior to transmission of a rekeying confirmation message to an authenticator;

continuing to use the first pair-wise key for transmission and delaying use of the second pair-wise key for transmission until after receipt of a rekeying confirmation message;

reading an Extended Key ID bit in a key ID field of received unicast packets to determine whether to toggle between the first and second pair-wise keys to decrypt each received unicast packet, the key ID field including a key ID portion and the Extended Key ID bit, the key ID portion identifying one of a plurality of keys, the Extended Key ID bit indicating whether to toggle between presently installed keys; and

supporting reception of the unicast packets with both the first key and the second key until a predetermined period of time after transmission of the rekeying confirmation message,

wherein the installing is performed by processing circuitry of the supplicant and the current and new pair-wise keys are stored in unicast key ID space of a memory.

21. The method of claim 20 further comprising delaying installation of the second key for transmission until immediately after transmission of the rekeying confirmation message.

22. The method of claim 20 further comprising uninstalling the first key for use in receiving after the predetermined period of time after transmission of the rekeying confirmation message.

23. The method of claim 22 wherein the rekeying confirmation message is a fourth message of a four-way handshake for rekeying.

24. The method of claim 22 wherein the method further comprises alternating use of two key identifiers between sequential handshakes to prevent deletion of the first key.