Research And Implementation On Security Protocol Based On Vehicle FlexRay Bus Network

With the rapid development of Internet technology,sensor technology and assisted driving technology,and people’s increasing consumer demand,intelligent and connected cars will inevitably become the development trend of modern automobiles.Thanks to this development trend,intelligent connected cars provide users with richer in-vehicle functions and applications,improving the driving experience.These functions and applications make the car increase the access interface for interacting with external information,and these interfaces will also become access points for hackers to attack,making the car’s information security risk extremely high.In recent years,automotive information security incidents have occurred frequently,and the information security problem of intelligent connected cars is facing unprecedented challenges.The main reason is that the internal network of modern automotive control systems was not designed with information security issues in mind at the beginning.Once a node in the network is attacked by a hacker,the hacker can use the node to perform forgery and replay attacks to control the vehicle or destroy the vehicle’s operating status,which seriously threatens the life and property safety of the owner.Therefore,it is necessary to design an effective information security defense mechanism for the automotive bus network in response to the information security vulnerabilities of the intelligent connected car.The on-board FlexRay bus network is a new-generation automotive bus network.Compared with the traditional CAN bus,the FlexRay bus has significant advantages in terms of transmission rate,topology flexibility,and reliability.And the FlexRay bus uses a time trigger mechanism to minimize the information delay and jitter as much as possible,ensuring the synchronization and high real-time transmission,so it is very suitable for automotive wire control systems.However,although the advantages of the FlexRay bus are clear,like the CAN bus,it did not consider information security at the beginning of the design,making the FlexRay bus network extremely vulnerable to the intrusion of illegal nodes and a series of malicious attacks such as illegal eavesdropping,forgery,and replay.Therefore,it is necessary and meaningful to research and design the information security protocol of the vehicle FlexRay bus network.This paper first analyzes the characteristics of the FlexRay bus and the security threats and security requirements it faces,and on the basis of fully considering the shortcomings of the in-vehicle ECU node’s limited bandwidth,insufficient computing capacity and storage capacity,proposes an information security protocol that can meet the real-time communication requirements of the in-vehicle FlexRay bus.The main work of this paper is as follows:(1)Briefly describe the development process and current status of intelligent connected cars,analyze and summarize the information security threats faced by intelligent connected cars,and summarize the current research status of vehicle bus information security issues at home and abroad;(2)Analyze the advantages of the FlexRay bus compared to other automotive buses,and introduce the FlexRay bus protocol from three aspects: the physical layer,the data link layer,and the clock synchronization algorithm;(3)Analyze the characteristics and limitations of the network nodes in the vehicle FlexRay bus,and summarize the information security requirements of the vehicle FlexRay bus;put forward the hypothesis model of the protocol,and redesign the FlexRay message format;and divide the FlexRay vehicle information security protocol into two modules according to the different requirements of the real-time communication and security in the vehicle start-up stage and driving stage,They are node identity authentication module and network security encryption module,and introduce the information security design strategy of the corresponding module;finally,put forward the security performance index of the protocol;(4)Introduces the design of the information security protocol of the FlexRay bus network in detail.For the node identity authentication module,this paper deeply analyzes the DH key distribution protocol,the challenge response principle and the asymmetric encryption algorithm RSA,and expounds the identity authentication and key distribution process based on the challenge response mode,DH key exchange protocol and the asymmetric encryption algorithm RSA algorithm,which guarantees the authenticity of the node identity and the security of the key distribution process;and for the network security encryption module,deeply analyzes the algorithm principle of symmetric encryption algorithm RC5 and hash encryption algorithm bkdr-hash,and describes the network node security communication process based on symmetric encryption algorithm RC5 and bkdr-hash algorithm in detail,ensuring the confidentiality,authenticity and freshness of the data transmitted in the network;(5)Based on the 16 bits vehicle microcontroller MC9S12XF512 developed by Freescale company,this paper simulates the wire control subsystem in the automotive environment and analyzes and compares the experimental results from two aspects of effectiveness and real-time.Experiments show that,in terms of effectiveness,the security protocol proposed in this paper can guarantee the legitimacy of the identity of the nodes connected to the bus and protect the confidentiality,authenticity and freshness of the data transmitted in the bus;in terms of real-time,the communication delay caused by the protocol proposed in this paper is within the acceptable range no matter in the start-up stage or normal driving stage of the vehicle,and does not affect the real-time communication of the vehicle,therefore,it can effectively provide information security protection for vehicles.