5G • Security
K_AMF
Access and Mobility Function Key
Core security key derived from K_SEAF by the AMF to generate NAS security and base station root keys.
Technical Explanation
The AMF derives K_AMF from K_SEAF using the UE's SUPI and an uplink NAS COUNT value. K_AMF is the parent key for: K_NASenc (NAS ciphering), K_NASint (NAS integrity), and K_gNB (the root key pushed to the gNodeB over N2).
Key Functions
- Derived directly from K_SEAF by the serving AMF
- Parent key generating all NAS protection keys and base station root keys
- Re-derived during mobility across AMFs to prevent key reuse
Specifications
3GPP TS 33.501
Interfaces
N1
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