A.13 KAMF to KAMF‘ derivation in mobility

A.13 K_AMF to K_AMF‘ derivation in mobility

33.5013GPPRelease 18Security architecture and procedures for 5G SystemTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

Derivation of K_AMF‘ from K_AMF during mobility shall use the following input parameters.

– FC = 0x72

– P0 = DIRECTION

– L0 = length of DIRECTION (i.e. 0x00 0x01)

– P1 = COUNT,

– L1 = length of COUNT (i.e. 0x00 0x04)

The input key KEY shall be K_AMF.

When K_AMF‘ is derived in handover, DIRECTION shall be 0x01 and COUNT shall be the downlink NAS COUNT of the 3GPP access.

When K_AMF‘ is derived in idle mode mobility (i.e., mobility registration update), DIRECTION shall be 0x00 and COUNT shall be the uplink NAS COUNT of the 3GPP access used in the Registration Request.