5G • Security
K_SEAF
Security Anchor Function Key
Master anchor security key derived by AUSF during primary authentication and securely stored in AMF.
Technical Explanation
K_SEAF is computed by the AUSF from K_AUSF and the serving network identity (PLMN ID): K_SEAF = KDF(K_AUSF, Serving Network Name). It acts as the cryptographic root of trust for all subsequent session keys in the visited serving network.
Key Functions
- Master security anchor key anchoring subscriber trust in the visited network
- Derived from K_AUSF bound to the specific Serving PLMN ID
- Stored securely within the AMF to derive downstream radio and NAS keys
Specifications
3GPP TS 33.501
Interfaces
N12
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