Extensible Authentication Protocol Authentication and Key Agreement (EAP-AKA) Optimization

• US 20100017603A1
• Filed: 07/18/2008
• Published: 01/21/2010
• Est. Priority Date: 07/18/2008
• Status: Active Grant

• Current Assignee: Amdocs Canadian Managed Services Inc. (Amdocs Ltd.), Amdocs Development Limited (Amdocs Ltd.)
• Original Assignee: Bridgewater Systems Corp. (Amdocs Ltd.)
• Inventors: Jones, Mark
• Granted Patent: US 8,245,039 B2
• Time in Patent Office: Days
• US Class Current: 713/168
• CPC Class Codes: H04L 2209/42 Anonymization, e.g. involving pseudonyms
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/0844 with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

Systems and methods are described for improved authentication of subscribers wishing to connect to a wireless network using the EAP-AKA protocol. Embodiments exploit the requirement that the client store and transmit the Pseudonym and Fast Re-authentication Identities upon request. By using the Fast Re-authentication Identity to store session state key information, the need for the AAA server to store and replicate the EAP-AKA key information for every session is eliminated.

Claims

1. A method for generating a temporary pseudonym identity associated with a subscriber, comprising:

receiving a master pseudonym identity associated with the subscriber;

generating a ps_mk by applying a pseudo-random number function to a server-key, wherein a timestamp is associated with the server key;

partitioning a ps_mk into at least a ps_ck and a ps_ik;

generating a ps_payload by applying a two-way encryption function to the master pseudonym identity and the ps_ck;

generating a ps_mac by applying a hashing function to a concatenation of the ps_payload and the ps_ik; and

generating a temporary pseudonym identity by concatenating the ps_mac, the timestamp, and the ps_payload.

2. The method of claim 1, wherein the ps_ck is the first 64 bits of the ps_mk, and the ps_ik is the next 64 bits of the ps_mk.

3. The method of claim 1, wherein the hashing function is the SHA-1 algorithm.

4. The method of claim 1, wherein the two-way encryption function is the exclusive or (XOR) salted MD5 encryption algorithm.

5. A method for generating a fast re-authentication identity for use in an EAP-AKA fast re-authentication, comprising:

generating a first digital value by applying a first hashing function to a concatenation of a server-key and a subscriber password, wherein a timestamp is associated with the server key;

generating an inner_mk by applying a first pseudo-random number function to the first digital value;

generating an inner_ck by extracting a first 128 bits of inner_mk;

generating an inner_payload by applying a first two-way encryption function to the inner_ck and a concatenation of a master key and a counter;

generating an outer_mk by applying a second pseudo-random number function to the server key;

partitioning the outer_mk into at least an outer_ck and an outer_ik;

generating an outer_payload by applying a second two-way encryption function to the outer_ck and a concatenation of the inner_payload and a Master Pseudo Id;

generating an outer_mac by applying a second hashing function to a concatenation of the outer_payload and the outer_ik; and

generating a fast re-authentication identity by concatenating the outer_mac, the timestamp, and the outer_payload.

6. The method of claim 5, wherein the outer_ck is the first 64 bits of the outer_mk, and the outer_ik is the next 64 bits of the outer_mk.

7. The method of claim 5, wherein the first and second hashing functions are the SHA-1 algorithm.

8. The method of claim 5, wherein the first and the second two-way encryption functions are the exclusive or (XOR) salted MD5 encryption algorithm.

9. A method for validating a pseudonym identity associated with a subscriber, comprising:

receiving a pseudonym identity associated with the subscriber;

extracting a timestamp, a ps_payload and a rcvd_mac from the received pseudonym identity;

determining a server key using a look-up table and the timestamp;

generating a ps_mk by applying a pseudo-random number function to the server-key;

partitioning the ps_mk into at least a ps_ck and a ps_ik;

generating a ps_mac by applying a hashing function to a concatenation of the ps_payload and the ps_ik;

comparing the ps_mac and the rcvd_mac; and

if comparing reveals a match, determining a Master-Pseudo-Id by applying a decryption function to the ps_payload and the ps_ck.

10. The method of claim 9, wherein the ps_ck is the first 64 bits of the ps_mk, and the ps_ik is the next 64 bits of the ps_mk.

11. The method of claim 9, wherein the hash function is the SHA-1 algorithm.

12. The method of claim 9, wherein the decryption function is associated with the exclusive or (XOR) salted MD5 encryption algorithm.

13. A method for validating a fast re-authentication identity for a subscriber for use in an EAP-AKA fast re-authentication, comprising:

receiving a fast re-authentication identity associated with the subscriber;

extracting a timestamp, an outer_payload and a rcvd_mac from the received fast re-authentication identity;

determining a server key using a look-up table and the timestamp;

generating an outer_mk by applying a first pseudo-random number function to the server-key;

partitioning the outer_mk into at least an outer_ck and an outer_ik;

generating a outer_mac by applying a first hashing function to a concatenation of the outer_payload and the outer_ik;

comparing the outer_mac and the rcvd_mac; and

if comparing does not reveal a match, rejecting the received fast re-authentication identity and stop;

if comparing does reveal a match, determining a Master-Pseudo-Id and an inner_payload by applying a first decryption function to the outer_payload using the outer_ck;

retrieving a subscriber password from a subscriber database using the Master-Pseudo-Id;

generating an inner_mk by applying a second pseudo-random number function to an output of applying a second hashing function to a concatenation of the server-key and the subscriber password;

extracting an inner_ck, wherein the inner_ck is a first 128 bits of the inner_mk;

determining a master-key (MK) and a counter by applying a second decryption function to the inner_payload using the inner_ck; and

regenerating master session key (MSK) and generating K_encr and K_aut using the master-key (MK) and the counter.

14. The method of claim 13, wherein the outer_ck is the first 64 bits of the outer_mk, and the outer_ik is the next 64 bits of the outer_mk.

15. The method of claim 13, wherein the first and second hashing functions are the SHA-1 algorithm.

16. The method of claim 13, wherein the first and second decryption algorithms are associated with the exclusive or (XOR) salted MD5 encryption algorithm.