A Group Key Management Scheme based on Elliptic Curve Cryptography for Virtual Coupling Train

Abstract

Virtual Coupling is a promising technique which can forming trains into a train group and also separating again while driving. Trains are electronically coupled via wireless communications, the position and speed information of each train must be shared in real time between the preceding and following trains. The main issue is that the trains are communicating via wireless channel, and there are many ways to attack the wireless channel. Therefore, we need an appropriate key distribution mechanism such as Public Key Infrastructure(PKI) in order to secure the wireless communication. Additionally, the communication between coupled train is time-critical, thus, the processing delay should be reduced as small as possible. In this paper, we propose a group key management scheme based on the Elliptic Curve Diffie-Hellman key distribution mechanism. The communication rounds and computational cost are the two most important factors when the number of group members is very large. In our proposed scheme, we used one and a half of communication round to improve the efficiency of group key management, thereby reduced the processing delay. Additionally, we used LTE-R communication protocol instead of the existing GSM-R protocol to improve the communication performance. We evaluated the performance from two different perspective, first is processing delay and the second is communication delay. In the processing delay, we compared the traditional public key cryptosystem with our proposed scheme. As the result, the performance of group key generation is similar when the number of group trains is small, but our proposed scheme showed better performance when the number of trains increased. The time used for encryption and decryption with our proposed scheme is always faster than RSA, thereby the proposed scheme can provide an efficient and reliable security to virtual coupling environment.