The Authentication Server Function (AUSF) provides subscriber authentication, normally based on SIM. AUSF Supports:

  * Authentication request from access network
  * Interaction from UDM for auth generate: 5G AKA only (see AKMA Procedure)
  * Storage of Kausf until removed by AMF or replaced

Handles routing based on SUCI and SUPI

Manages authentication confirmation timeout

Supports re-synchronization procedure

Maintains session states in an external centralized database for stateless operations

AKMA Procedures

Bibliography:

  * [[https://www.linkedin.com/pulse/ausf-authentication-server-function-5g-nr-techlte-world|https://www.linkedin.com/pulse/ausf-authentication-server-function-5g-nr-techlte-world]]
  * [[https://www.alepo.com/products-services/authentication-server-function-5g-ausf/|https://www.alepo.com/products-services/authentication-server-function-5g-ausf/]]
  * [[https://www.3gpp.org/technologies/akma|https://www.3gpp.org/technologies/akma]]
  * [[https://i0.wp.com/yatebts.com/wp-content/uploads/2021/07/5gsa-registration_ausf.png?ssl=1|https://i0.wp.com/yatebts.com/wp-content/uploads/2021/07/5gsa-registration_ausf.png?ssl=1]]
  * [[https://www.iplook.com/products/5gc-udm-ausf|https://www.iplook.com/products/5gc-udm-ausf]]