TAGKA: Threshold Authenticated Group Key Agreement Protocol Against Member Disconnect for UANET

The development of unmanned aerial vehicle (UAV) technology has been advancing rapidly and is widely applied in various domains. Compared to a single UAV, the multi-UAV system, known as the UAV Ad Hoc Network (UANET), can collaborate to accomplish complex tasks more efficiently. Due to the UAVs communicating through open wireless channels, they are vulnerable to various attacks. Group key agreement protocols are often used to guarantee the security of UANET communication. However, the high dynamics of UAVs and the instability of the wireless links often result in certain UAVs temporarily losing connection with the group, rendering them incapable of participating in the group key agreement process. Regrettably, existing literature on group key agreement does not consider this issue, which makes them not applicable to UANET. To address this issue, we propose a threshold authenticated group key agreement protocol (TAGKA) that can resist the disconnection of group members. Then, considering that the temporarily disconnected UAVs need to obtain the latest group key after the communication links are recovered, we design a group key recovery protocol. The security of the scheme is proved under the random oracle model. Moreover, formal security verification using the Tamarin and rigorous informal security analysis is also performed. Finally, we use NS-3 to simulate the protocol, and the experimental results show that our protocol can be effectively applied to UANET.