he NG-C interface. 5) Following the security of the NAS signaling, the 5G core network: - checks that the mobile is not banned (blacklisted); - transfers the UE context to the AMF function which registers the mobile; - updates policy rules at the UE context level; - establishes the UPF (User Plane Function) transport plan of the PDU sessions to be activated (if they exist). At the end of these operations, the AMF function transmits the UE context to the NG-RAN access, including: - the derivation key for securing the KgNB radio link; - the mobility restriction list; - the mobile radio capacities; - the security algorithms used by the mobile; - the authorized NSSAI indicator; - the RSFP index (RAT Frequency Selection Priority); - information concerning PDU sessions (identity of the session, S-NSSAI indicator). The establishment of the UE context to the radio node is initiated by the AMF function via the NGAP Initial Context Setup Request. 6) Using the KgNB security key, the base station secures the radio link via the RRC SecurityModeCommand request. On receiving this message, the mobile also derives the KgNB radio access security key and: - calculates the integrity key of RRC signaling; NG-RAN and 5G-NR - checks the integrity of the message received; - derives the encryption key from the radio link; - starts the procedure for securing the SRB signaling radio support. The mobile responds with the RRC SecurityModeComplete message if the integrity check is successful. At this step, the messages exchanged are protected in integrity but are still not ciphered. 7) The base station responds to the first message transmitted by the mobile (RRC SetupComplete REGISTRATION REQUEST) via the RRC Reconfiguration request, which carries the REGISTRATION ACCEPT message. The RRC Reconfiguration message also enables us to: - configure the measurement report at the mobile level; - add secondary cells in the case of carrier aggregation (SCells); - configure the DRB (Data Radio Bearer) radio support. The base station confirms the registr