# Information Fusion in Autonomous Vehicle Using Artificial Neural Group Key Synchronization
## 2 Related Work  
The first degree of trust is used in some models [15], but it appears to be ineffective. PKI was used in certain models to share keys for identity verification, achieving the second degree of trust. The third degree of trust should be used for routine V2X data transfer, with fourth degree of trust accessible as a backup strategy for critical data transfer. The shared keys for vehicle transmissions in this network are temporary keys known as Activation Tokens (ATs). ATs are distributed once every small length of time (e.g., 10 min). As depicted in Figure 2, the procedure begins with a request from one vehicle to update ATs to RSUs, which is then forwarded to a distant key exchange platform, which validates the identification and replies. The vehicles and RSUs remain inactive throughout this period until the key sharing server responds. If the vehicle's request is genuine, RSUs will transfer fresh ATs to the vehicle for use in the following time frame. In a different application scenario described in [9], the RSU verifies the digital certificate of the updated AT queries before forwarding them if they are legitimate. On the RSU side, this will undoubtedly result in longer delays. Without taking into account the delay between RSUs and PKI servers, the overall delay for AT upgrading may be over 400 ms. Furthermore, this delay will occur every 10 min, potentially affecting V2X transmission, particularly security messages, which have a 50 ms time restriction. It is presumed that the V2X data transmission uses a public-key cryptosystem to validate V2X messages. The data of the V2X communication are not encoded in this case. Vehicle 1 would wish to send security information regarding an urgent situation, such as a vehicle breakdown, as depicted in Figure 3. This information will be created and structured in accordance with the V2X protocol, which includes both the payload and safety portions of the V2X information. A message-digest algorithm, such as the HASH, will also be used to create the specific pattern for consistency authentication in this V2X message. The given information will then be validated using a digital signature. When a neighboring RSU gets V2X information, it will first verify the information source's authenticity and information integrity before accessing the content of the information. After all safety-related parts have been validated, the information will be processed and warning information will be sent to all surrounding cars. The RSU would then have to execute the HASH and digital signature operations to transmit this warning information to adjacent vehicles. Before the information payload is processed, the given information and information integrity must be examined and validated by the cars in the vicinity. Four hash functions and two ECDSA signatures and authentication procedures run on vehicles and the RSU, respectively, will create the delay caused by safety actions in this scenario. In [16], the researchers compare their research on real-world V2X systems. According to the results of [16], the ECDSA technique takes between 5.5 ms and 7.2 ms  
Figure 3: Exchange of information in urgent situation. Figure 2: PKI-based key shairing procedure in [9]. every transaction using a 224 and 256-bit key. For authentications, the ECDSA technique with 224-bit key takes 7.2 ms and the 256-bit key takes 9.4 ms, respectively. The efficiency on ARM9 devices may be substantially slower, as the authors highlighted, with one authentication process taking 150 ms. Many prior studies [17] on both the hardware and software sides have developed and improved Hash algorithms, notably SHA-2 functions. Yet, the energy and computation capacity of integrated CPUs in cars have always been restricted. Measurement of SHA-2 efficiency on ARM series CPUs may be used to make an estimate, and a single SHA2 computation will take less than 1 ms. According to [18], depending on the physical device and length of the input information, SHA-3 might be 2 to 3 times worse. [PERSON] et al.