 of the security of the access stratum. RLC mode Transport Logical channel channel Physical channel DL-SCH PDSCH SecurityModeCommand UL-SCH PUSCH SecurityModeComplete SecurityModeFailure Table 9.5. Support for messages relating to the activation of security The SecurityModeCommand message is transmitted by the gNB entity to define the algorithms used for the encryption of SRB and DRB media and for the integrity check of the SRB media. Upon receipt of the SecurityModeCommand message, the mobile performs the following actions: - derives the KgNB key from the KAMF key; - derives the KRRCint integrity key and the Kupint key associated with the integrity protection algorithm; - checks the integrity protection of the SecurityModeCommand message; - starts the integrity protection of the SRB media. The SecurityModeComplete message is transmitted by the mobile to confirm the activation of security. Encryption is operational after transmitting this message. The SecurityModeComplete message is not encrypted but integrity protected. The SecurityModeFailure message is transmitted by the mobile to indicate the failure to activate security. 9.2.4. Connection reconfiguration Connection reconfiguration messages are used to modify an existing RRC connection. The procedure concerns the following operations: - the establishment, modification and release of DRB media; - the establishment, modification and release of radioelectric measurements; NG-RAN and 5G-NR - the establishment, modification and release of SCell secondary cells; - triggering of the handover. Table 9.6 provides the characteristics of the message support relating to the reconfiguration of the connection. RLC mode Transport Physical Logical channel Channel Channel DL-SCH PDSCH Reconfiguration UL-SCH PUSCH ReconfigurationComplete Table 9.6. Support for messages relating to the reconfiguration of the connection The Reconfiguration message is transmitted by the gNB entity and allows us to configure the parameters of the PHY, MAC, RLC, PDCP and SDAP layers. The Reconfigur