LEI Ao Chibueze Ogah Philip Asuquo Haitham Cruickshank SUN Zhili

Abstract Intelligent transportation system （ITS） is proposed as the most effective way to improve road safety and traffic efficiency. However， the future of ITS for large scale transportation infrastructures deployment highly depends on the security level of vehicular communication systems （VCS）. Security applications in VCS are fulfilled through secured group broadcast. Therefore， secure key management schemes are considered as a critical research topic for network security. In this paper， we propose a framework for providing secure key management within heterogeneous network. The security managers （SMs） play a key role in the framework by retrieving the vehicle departure information， encapsulating block to transport keys and then executing rekeying to vehicles within the same security domain. The first part of this framework is a novel Group Key Management （GKM） scheme basing on leaving probability （LP） of vehicles to depart current VCS region. Vehicle's LP factor is introduced into GKM scheme to achieve a more efficient rekeying scheme and less rekeying costs. The second component of the framework using the blockchain concept to simplify the distributed key management in heterogeneous VCS domains. Extensive simulations and analysis are provided to show the effectiveness and efficiency of the proposed framework： Our GKM results demonstrate that probability?based BR reduces rekeying cost compared to the benchmark scheme， while the blockchain decreases the time cost of key transmission over heterogeneous networks.

Keywords leaving probability； blockchain； group key management； heterogeneous； vehicular communication systems （VCS）

1 Introduction

Vehicular communication systems （VCS） supports not only message exchange among vehicles， but between cars and infrastructure facilities as well. Infrastructure access points in VCS are called Road Side Units （RSUs） [1]. RSU acts as a base station in VCS and covers a small section on the road. Traditional VCS is comprised of multiple RSU cells and offers a platform among intelligent transportation systems （ITS） for vehicles to exchange different kinds of messages such as safety notification messages. With the help of VCS， ITS can offer a more safe and efficient traffic management， which is the basic function of ITS. Moreover， commercial applications， such as electric vehicle charging [2]， can be implemented on a dedicated platform. A recent report from U.S Department of Transport （DoT） shows that 82% of the accidents can be prevented by using ITS systems [3]. Even though significant developments have taken place over the past few years in the area of VCS， security issues， especially key management schemes are still an important topic for research. High mobility， large volume， frequent handoff of vehicular nodes and heterogeneity networks pose different challenges compared to the traditional mobile networks.