Research Of Data Compression And Network Security For In-Vehicle Flexray Communication Network

With the rapid development of internet of vehicle in recent year,the vehicle itself is no longer a travel tool but more like a modern computer running on road.But,this improvement also bring the security problem to in-vehicle bus system,paving the way of intrusion into vehicle for hackers.Once the data transmitted on bus is controlled or manipulated by hacker there will be a significant threat to the safety of passengers’ life and possession.Since there is no in-vehicle communication protocols take security into consideration,in this research,a secure communication protocol and data compression method is produced for FlexRay,the potential next generation in-vehicle communication protocol,to secure in-vehicle network and reduce the interference of real-time.First,to secure in-vehicle network,the security protocol composed of encryption,authentication and key distribution method was designed.The AES algorithm was used in CTR mode for encryption;integrity and freshness of data was achieved by the HMAC algorithm;by using on-way key chain with a feature of infeasible to invert,the session key was distributed to every receiver in plaintext in the nearest communication cycle immediately after the one expire.Then,with proper management,all procedures needed in security protocol were enabled to achieve secure communication between transmitter and receivers.Besides,for purpose of reducing interference of real-time for original task of embedded ECU,a data compression method was designed to minimize the amount of data need to be processed by security algorithm,which could release the CPU.The basic principal of data compression was transmitting the variation rather than complete of data in contiguous cycle.The compressed data,the variation,will be obtained by XOR operation between data in contiguous cycle and transmitted in original frame added with several indicator bits for convenience of decompress.Finally,to evaluate effectiveness of the design in this paper,a combined experiment was carry out with FlexRay evolution board,the embedded ECU,and simulated bus tool CANoe and the real traffic data of in-vehicle bus.The security protocol and data compression algorithm was wrote in C language under Codewarrior IDE,then download in ECU.Through CANoe,attack frame can be send to ECU,and traffic data can be observed,which could deduce that the security protocol running successfully on ECU and attack defensiveness was robust.Furthermore,after compression,the CPU load of overall security algorithms could be reduce by 7.54%and 6.23%in transmitter and receiver respectively.