Section: 5.2.3 User data and signalling data integrity
Content: The UE shall support integrity protection and replay protection of user data between the UE and the gNB. The UE shall support integrity protection of user data at any data rate, up to and including, the highest data rate supported by the UE. The UE shall activate integrity protection of user data based on the indication sent by the gNB. The UE shall support integrity protection and replay protection of RRC and NAS-signalling. The UE shall implement the following integrity protection algorithms: NIA0, 128-NIA1, 128-NIA2 as defined in Annex D of the present document. The UE may implement the following integrity protection algorithm: 128-NIA3 as defined in Annex D of the present document. The UE shall implement the integrity algorithms as specified in TS 33.401[ 3GPP System Architecture Evolution (SAE); Security architecture ]  [10] if it supports E-UTRA connected to 5GC. Integrity protection of the user data between the UE and the gNB is optional to use. NOTE: Integrity protection of user plane adds the overhead of the packet size and increases the processing load both in the UE and the gNB. Integrity protection of the RRC-signalling, and NAS-signalling is mandatory to use, except in the following cases: All NAS signalling messages except those explicitly listed in TS 24.501[ Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3 ]  [35] as exceptions shall be integrity-protected. All RRC signalling messages except those explicitly listed in TS 38.331[ NR; Radio Resource Control (RRC); Protocol specification ]  [22] as exceptions shall be integrity-protected with an integrity protection algorithm different from NIA0, except for unauthenticated emergency calls. The UE shall implement NIA0 for integrity protection of NAS and RRC signalling. NIA0 is only allowed for unauthenticated emergency session as specified in clause 10.2.2.