The present document specifies the security architecture, procedures and information flows needed to protect the mission critical service (MCX). The architecture includes mechanisms to protect the Common Functional Architecture and security mechanisms for mission critical applications. This includes Push-To-Talk (MCPTT), Video (MCVideo) and Data (MCData). Additionally, security mechanisms relating to on-network use, off-network use, roaming, migration, interconnection, interworking and multiple security domains are described. This specification complements the Common Functional Architecture defined in TS 23.280, the functional architecture for MCPTT defined in TS 23.379, the functional architecture for MCVideo defined in TS 23.281, the functional architecture for MCData defined in TS 23.282 and mission critical services using 5GS in TS 23.289. The MC service can be used for public safety applications and also for general commercial applications e.g. utility companies and railways. As the security model is based on the public safety environment, some MC security features may not be applicable for commercial purposes.

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