IP Library Granted Patent US 12707263
Granted Patent B2
US 12707263 · App. 18/030,952 · Granted Aug 11, 2026

Method of user equipment related to authentication and key agreement procedure, and user equipment

Inventors: Kundan Tiwari (Tokyo, JP); Toshiyuki Tamura (Tokyo, JP)
Assignee: NEC CORPORATION
H04W12/062H04W8/02H04W12/0431
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Quick Facts
Patent No.
US 12707263
App. No.
18/030,952
Granted
Aug 11, 2026
Kind
B2
Abstract

A procedure to establish latest security key in a UE and a network is disclosed. More specifically, the procedure defines various method to establish latest Kausf in the UE and the network and make the UE and network uses the same Kausf in various security procedure.

Claims (38)

1 . A method of a User Equipment (UE) which stores a first K AUSF (Authentication Server Function) , the method comprising:

in a 5G Authentication and Key Agreement (AKA) based primary authentication and key agreement procedure, receiving, from an Access and Mobility Management Function (AMF), an authentication request message;

computing response information based on the authentication request message;

deriving second K AUSF based on the authentication request message; and

returning, to the AMF, an authentication response message including the response information;

receiving, from the AMF, a Non-Access-Stratum (NAS) message after the 5G AKA based primary authentication and key agreement procedure is successful; and

in a case where the UE receives the NAS message,

deleting the first K AUSF ,

considering the second K AUSF to be valid K AUSF ; and

resetting a counter to zero.

2 . The method according to claim 1 ,

wherein the counter is a Steering of Roaming (SoR) counter.

3 . The method according to claim 1 ,

wherein the counter is a UE Parameters Update (UPU) counter.

4 . The method according to claim 1 , further comprising:

using the second K AUSF in a steering of roaming security mechanism or a UE parameters update via Unified Data Management (UDM) control plane procedure security mechanism.

5 . The method according to claim 1 ,

wherein the first K AUSF is stored in the UE before the 5G AKA based primary authentication and key agreement procedure is initiated.

6 . A User Equipment (UE) which stores a first K AUSF (Authentication Server Function) , comprising:

at least one memory storing instructions; and

at least one processor configured to execute the instructions to:

receive, in a 5G Authentication and Key Agreement (AKA) based primary authentication and key agreement procedure, from an Access and Mobility Management Function (AMF), an authentication request message;

compute, in the 5G AKA based primary authentication and key agreement procedure, response information based on the authentication request message;

derive, in the 5G AKA based primary authentication and key agreement procedure, second K AUSF based on the authentication request message; and

return, in the 5G AKA based primary authentication and key agreement procedure, to the AMF, an authentication response message including the response information;

receive, from the AMF, a Non-Access-Stratum (NAS) message after the 5G AKA based primary authentication and key agreement procedure is successful; and

in a case where the UE receives the NAS message,

delete the first K AUSF ;

consider the second K AUSF to be valid K AUSF ; and

reset a counter to zero.

7 . The UE according to claim 6 ,

wherein the counter is a Steering of Roaming (SoR) counter.

8 . The UE according to claim 6 ,

wherein the counter is a UE Parameters Update (UPU) counter.

9 . The UE according to claim 6 ,

wherein the at least one processor is further configured to execute the instructions to use the second K AUSF in a steering of roaming security mechanism or a UE parameters update via Unified Data Management (UDM) control plane procedure security mechanism.

10 . The UE according to claim 6 ,

wherein the first K AUSF is stored in the UE before the 5G AKA based primary authentication and key agreement procedure is initiated.