An Asynchronous Group Key Exchange Protocol with Threshold Join Function for Internet of Vehicles

The Internet of Vehicles (IoV) makes vehicles smarter by connecting them with a variety of IoT devices, and thus group communication is one of the main communication ways. To ensure communication security, the group key exchange protocols are widely used in practice. Recently, Gordon et al. presented an asynchronous tree-based group key exchange protocol (GKE), and their protocol forms the basis of two draft RFCs. While their work discusses dynamic group settings, it does not provide a specific construction. To fill the gap, inspired by Gordon's work, we design a new flexible group key exchange protocol with threshold join function. The protocol not only inherits excellent traits of Gordon's work such as asynchronous setting and post-compromise security, but also achieves secure dynamic group member management by introducing the threshold cryptography techniques into the GKE. In addition, we implement a prototype of our protocol and evaluate its performance through extensive experiments. The experimental results demonstrate that the proposed protocol is practical and efficient for groups of a realistic size for IoV.