# Efficient Secure Mechanisms for In-Vehicle Ethernet in Autonomous Vehicles
## 3 Automotive Ethernet Security Protocol
### The Overall Network Security Scheme for In-Vehicle Ethernet  
The transmission environments of in-vehicle Ethernet networks can be broadly categorized into two main groups:  
1. In-vehicle multimedia signals: * Functionality: In-vehicle infotainment signals, comprising audio, video, navigation, and diagnostics, are often perceived as non-safety-critical. However, their stable transmission is crucial for passenger comfort and indirectly reflects the reliability of the vehicle, thus influencing the passengers' safety perception. * Security Challenges: As evidenced by the 2015 Jeep hack, a breach in the multimedia system can serve as a gateway to manipulate critical vehicle controls. Therefore, safeguarding both multimedia and vehicle control networks is paramount. * Attack Types: These include data theft (e.g., hackers attempting to illegally copy entertainment system data or analyze user behavior) and denial-of-service attacks (blocking multimedia signal transmission through sending numerous invalid requests) [33]. * Security Measures: To address these threats, this paper employs a combination of an improved IAES-128 algorithm and an IMD5 algorithm for encryption and authentication of in-vehicle multimedia signals. IAES-128 optimizes encryption speed for multimedia data, while IMD5 improves data integrity verification efficiency.
2. In-vehicle control signals: * Functionality: Encompass steering, braking, power, and lighting signals, these control signals are pivotal in determining the fundamental functionality and safety of the vehicle. * Transmission Requirements: During vehicle operation, it is imperative for control signals to be transmitted swiftly and accurately to ensure the stability and safety of the vehicle. * Attack Types: Common attack types include replay attacks (hackers capturing and resending legitimate control signals to deceive the system) and tampering attacks (modifying the content of control signals, such as sending erroneous braking commands) [34; 35]. * Security Measures: To mitigate these threats, this paper adopts a hybrid AES-ECC encryption mechanism with a higher security level to encrypt the control signals. This hybrid algorithm combines the efficiency of AES with the security of ECC, providing a high level of protection for critical vehicle control signals.  
Given the distinct characteristics of in-vehicle control signals and multimedia signals, we have implemented different security schemes tailored to each. In this study, these network security schemes have been applied to the constructed network topology, and the flowchart of the network security scheme is depicted in Figure 3. By combining various encryption and authentication algorithms, we can effectively defend against various attacks targeting in-vehicle multimedia and control signals, thereby ensuring the security and reliability of the automotive system. Additionally, in-vehicle Ethernet networks must feature high bandwidth and low latency while considering the intricate vehicle environment, including temperature, humidity, vibration, and electromagnetic interference, to ensure stable and reliable transmission.