Group Secret Key Generation Using Physical Layer Security for UAV Swarm Communications

In unmanned aerial vehicle (UAV) swarm networks, a group secret key (GSK) is required to enable secured UAV–UAV communications, multicast, and broadcast transmission. Moreover, it can be used for device authentication. Therefore, this article proposes an efficient GSK protocol denoted as the sequential secret group key (SSGK) algorithm for distributed UAV swarm-secured communications. The proposed protocol utilizes network coding to generate cooperation information that is transmitted on the channel and is uncorrelated with the generated secret key. The proposed protocol depends on the pairwise key generation process between pairs of UAVs. However, not all possible pairwise agreements are performed to minimize the time and signaling overhead, i.e., the pairwise key agreement is performed only between selected UAVs as a compromise between the required overhead transmission resources and the achieved redundancy level. The obtained results show that a redundancy level of 4 is sufficient to provide a reliable GSK generation process. The results also show that the performance of the key generation process highly depends on the channel bit error rate (BER), the number of UAVs, and the key length.