NAF Key Establishment via BSF Inversion

The patent applies preliminary action by establishing the security association before the actual service data transmission. The NAF initiates the security association setup in advance, obtaining security context and keys before pushing service information to the UE. This pre-establishment of security credentials prevents manipulation and replay attacks on the service delivery channel, as the security framework is already in place before any service communication occurs.

The patent applies inversion by reversing the traditional initiation direction. Instead of the UE initiating the security association establishment by sending B-TID to the NAF, the NAF initiates the process by sending a request to the BSF to obtain security context. This role reversal allows the service node to proactively establish security associations, eliminating the need for continuous UE-initiated requests and significantly improving efficiency for push-type services.

The patent applies the intermediary principle by introducing the BSF as a mediator between the NAF and the security credential storage. The NAF sends a request to the BSF containing the UE identity, and the BSF retrieves the appropriate security context (including B-TID and authentication vectors) from the HSS or local storage. This intermediary approach streamlines the process by centralizing security credential management, reducing the complexity that would otherwise exist if the NAF directly managed security credentials for multiple UEs.