 this procedure, the AMF function contacts UDM to obtain an authentication vector made up of a random number RAND, the authentication response expected from the mobile RES, the authentication token of the AUTN network, a 5G key (ngKSI) and the ABBA parameter deriving from the AMF (Anti-Bidding down Between Architectures) key. 3) The AMF function transmits the AUTHENTICATION REQUEST message containing the random number RAND, the seal of the AUTN network and the parameters ngKSI and ABBA to the mobile. The mobile locally calculates, from its private and secret key Ki (stored in the USIM module of its UICC card) and the random number RAND received, the seal of the AUTN network, which it compares with the value received. If the two values are identical, the 5G core network is authenticated and the mobile calculates, with the additional parameters ngKSI and ABBA, its RES authentication seal and the KASME key: - the AUTHENTICATION REQUEST message is carried by the RRC DLInformationTransfer message on the NR radio interface, and by the NGAP DOWNLINK NAS TRANSPORT message on the NG-C interface; - the AUTHENTICATION RESPONSE message is carried by the RRC ULInformationTransfer message on the NR radio interface, and by the NGAP UPLINK NAS TRANSPORT message on the NG-C interface. 4) The security of the NAS signaling is activated by the AMF function, which sends the NAS SECURITY MODE COMMAND message, checked for integrity with the KNASint key. This message contains the algorithms used to derive the KSEAF (SEcurity Anchor Function) key. NG-RAN Network - Procedures The KSEAF key is used to generate the encryption and integrity keys for NAS requests and generate the KgnB key: - the NAS SECURITY MODE COMMAND message is carried by the RRC DLInformation Transfer message on the NR radio interface, and by the NGAP DOWNLINK NAS TRANSPORT message on the NG-C interface; - the NAS SECURITY MODE COMPLETE message is carried by the RRC ULInformationTransfer message on the NR radio interface, and by the NGAP UPLINK NAS TRANSPORT message on t