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5G NR Security: Key Derivation and Termination Points

5g security nr key derivation termination point

This page provides an overview of 5G NR security basics, covering key derivation algorithms and security termination points.

Introduction:

Wireless security is paramount due to the open nature of the air interface. Consequently, various wireless technologies, including GSM, 3G, LTE, and 5G, employ a range of security algorithms to establish robust and secure wireless connections for users.

The main goal is to ensure the confidentiality and integrity of both user data and signaling information across different points within the 5G network. 5G NR offers security for the following:

  • User data (DRBs)
  • RRC Signaling (SRBs)

5G NR Security Key Derivation

5G security key derivation

Figure 1: 5G security key derivation algorithm

Figure 1 illustrates the 5G security key derivation algorithm as defined by the 5G NR standard. The table below explains the symbols used within the algorithm.

KeysDescription
Keys for AMF
KAMFDerived by ME
SEAF from KSEAF
Keys for NAS signalling
KNAS(int)Derived by ME and AMF from KAMF
KNAS(enc)Derived by ME and AMF from KAMF
Keys for gNB
KgNBDerived by ME and AMF from KAMF
Keys for UP trafficKUP(enc) , KUP(int)
Keys for RRC SignallingKRRC(int) , KRRC(enc)
Other intermediate keys
NHDerived by ME and AMF to provide forward security
KgNB*Derived by ME and gNB when performing a horizontal or vertical key derivation.

5G NR Security Key Termination Points

The following table outlines the 5G NR security termination points as described in 3GPP TS 38.300 Release 15 document.

Security PointCipheringIntegrity Protection
NAS SignalingAMFAMF
RRC SignalinggNBgNB
User Plane DatagNBgNB

References:

  • 3GPP TS 38.300 V15.2.0 (June 2018), NR and NG-RAN Overall Description; Stage 2