Inter-Network Function Authentication

In the 5G Service-Based Architecture, every Network Function authenticates to every other NF using mutual TLS at the transport layer plus OAuth2 access tokens at the application layer. The NRF acts as the authorisation server and issues short-lived JWT tokens scoped to the requested service, NF type, and PLMN. This combination prevents any compromised or rogue NF from invoking arbitrary services and replaces the implicit trust model that plagued earlier mobile generations.

Categories: Radio Access NetworkCore NetworkSecurity Controls

Inter-Network Function Authentication in context

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

The mobile core is where subscriber sessions, mobility and policy live. 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. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

To place Inter-Network Function Authentication in the wider telecom-security picture, review OAuth2 in 5G Core, HTTP, NRF Poisoning, 5G SBA, HTTP/2 Security in 5G and Mobile Network.

Related terms

Related topic hubs

  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.
  • SEPP Security N32-c/N32-f, PRINS, JWE and OAuth 2.0 at the 5G roaming edge.
  • Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.
  • 5G NEF Security Network Exposure Function security in the 5G core.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.