Badge-earners have developed an in-depth understanding of 5G security. This includes the architecture, domain security, authentication, key agreement, ciphering, integrity protection, identity concealment, 5G/4G security interworking (incl. dual connectivity) and mapping, mobility (handovers), and security procedures. They understand both the mechanisms and rationale of the various 5G security features, and how they build on the existing 3GPP security architecture.