Method for refreshing a pairwise master key
The present invention provides a method for communication involving a supplicant, an authenticator, and an authentication server having an established security association based on a first key. The supplicant and the authenticator also have an established security association based on a second key. The method may include modifying the second key using the first key in response to determining that a challenge response from the supplicant is valid.
1. A method of communication involving a supplicant, an authenticator, and an authentication server having an established security association based on a first key, the supplicant and the authenticator having an established security association based on a second key, the method being implemented in the authenticator and comprising:
receiving a challenge response from the supplicant over an air interface in response to transmitting a first challenge to the supplicant over the air interface, wherein the challenge response includes a second challenge generated by the supplicant and a first message authentication code determined using the first key, the first challenge, and the second challenge;
if the challenge response from the supplicant is valid, modifying the second key using the first key, the first challenge, and the second challenge.
2. The method of claim 1 , comprising:
transmitting the first challenge to the supplicant; and
determining whether the challenge response is valid.
3. The method of claim 2 , wherein transmitting the first challenge comprises providing a random number generated by the authenticator, and wherein the second challenge comprises at least one of a random number, a counter, and a nonce generated by the supplicant, the nonce comprising at least one of a random number and a counter.
4. The method of claim 3 , wherein determining that the challenge response is valid comprises validating the first message authentication code.
5. The method of claim 4 , comprising generating a second message authentication code using the first key, the first challenge, and the second challenge.
6. The method of claim 5 , comprising transmitting the second message authentication code to the supplicant over the air interface.
7. The method of claim 6 , wherein modifying the second key comprises determining the second key using a hash function of the first key, the first challenge, and the second challenge.
8. The method of claim 7 , comprising:
receiving an indication that the second message authentication code was validated by the supplicant.
9. The method of claim 1 , comprising determining at least one third key based upon the modified second key.
10. A method of communication involving a supplicant, an authenticator, and an authentication server having an established security association based on a first key, the supplicant and the authenticator having an established security association based on a second key, the method being implemented in the supplicant and comprising:
transmitting a challenge response to the authenticator over an air interface in response to receiving a first challenge from the authenticator over the air interface, wherein the challenge response includes a second challenge generated by the supplicant and a first message authentication code determined using the first key, the first challenge, and the second challenge;
receiving a second message authentication code from the authenticator over the air interface;
if the second message authentication code is validated, modifying the second key using the first key, the first challenge, and the second challenge.
11. The method of claim 10 , comprising receiving the first challenge from the authenticator.
12. The method of claim 11 , wherein receiving the first challenge comprises receiving a random number generated by the authenticator, and wherein the second challenge comprises at least one of a random number, a counter, and a nonce generated by the supplicant, the nonce comprising at least one of a random number and a counter.
13. The method of claim 12 , comprising validating the second message authentication code.
14. The method of claim 13 , wherein receiving the second message authentication code comprises receiving a second message authentication code generated by the authenticator using the first key, the first challenge, and the second challenge.
15. The method of claim 14 , wherein modifying the second key comprises determining the second key using a hash function of the first key, the first challenge, and the second challenge.
16. The method of claim 10 , comprising determining at least one third key based upon the modified second key.