Apparatuses, methods, and systems are disclosed for supporting remote unit reauthentication. One apparatus apparatus includes a processor and a transceiver that sends a first authentication message to a network function in a mobile communication network and receives a second authentication message from the network function in response to the first authentication message. Here, the first authentication message contains an indicator that the apparatus supports EAP Reauthentication Protocol and the second authentication message contains a key management domain name indicating a group of network functions that can share reauthentication security context. The processor derives reauthentication security context in response to successful authentication with the mobile communication network and locally stores the received key management domain name and the derived reauthentication security context for subsequent reauthentication with the mobile communication network.