AUSF (Authentication Server Function)

The Authentication Server Function is the 5G core network function that performs subscriber authentication on behalf of the AMF, executing the 5G-AKA or EAP-AKA' procedure with credentials supplied by the UDM. It generates session keys that bind the subscriber to the serving network, helping defeat false base station and interconnect attacks. AUSF compromise would allow forged authentication, so it must be deployed in the operator's most trusted security zone with strong API controls.

Categories: Radio Access NetworkCore NetworkRoaming and Interconnect

AUSF in context

The radio access network is where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations and downgrade attacks; defenses rest on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

The mobile core carries subscriber sessions, mobility and policy. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF.

To place AUSF in the wider telecom-security picture, review Grey Routing, Red Team, SUCI, Threat Intelligence, 5G and 5G SA — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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