How LTE Stuff Works?: LTE NAS: Security Mode Complete

Ø If the SECURITY MODE COMMAND message can be acceptable to the UE, then the UE shall send a SECURITY MODE COMPLETE message to the network

Ø If the MME requests IMEISV in the SECURITY MODE COMMAND message then the UE shall include its IMEISV in the SECURITY MODE COMPLETE message

Ø The SECURITY MODE COMPLETE message shall be integrity protected with the selected NAS integrity algorithm and the EPS NAS integrity key based on the K_ASME/K'_ASME

Ø Also, the UE shall cipher the SECURITY MODE COMPLETE message with the selected NAS ciphering algorithm and the EPS NAS ciphering key based on the K_ASME/K'_ASME

Ø After sending SECURITY MODE COMPLETE message, the UE shall cipher and integrity protect all the subsequent NAS messages with the selected NAS ciphering and integrity algorithms respectively

Ø After receiving SECURITY MODE COMPLETE message, the MME shall integrity protect and encipher all signalling messages with the selected NAS integrity and ciphering algorithms respectively

Reference: 3GPP TS 24.301

Example: SECURITY MODE COMPLETE

2 comments:

AnonymousOctober 20, 2017 at 8:04 AM
Can the eNB request IMEISV within an Identity Request message prior to the security mode?
KPJanuary 17, 2018 at 12:19 PM
The MME may include "IMEISV request" IE in the SECURITY MODE COMMAND message to request the UE to send its IMEISV with the corresponding SECURITY MODE COMPLETE message.

So I don't think that there is a need for this to be part of Identity procedure. Do you have any experience of this?