## 4 Implementation and Discussion
### Comparative Analysis  
The proposed system is also compared with some of the existing literature. Table 8 summarizes such comparison in terms of vehicle capacity, encryption techniques, Kerberos integration, gas, cost, delay parameters, and security attacks analysis.  
The variation of the number of vehicles indicates the scalability of the system, which can influence the network topology and the effects of network performances in denser topology. In the literature, refs. [12; 14; 15; 50; 51; 16] evaluated the parameters of the system considering the maximum number of vehicles to be 200 for the city area. Based on this, to evaluate the performance of our system we considered the number of vehicles from 1 to 200.  
The exact number of vehicles in the VANET system can vary based on factors such as the size of the area, specific use case (e.g., safety, traffic management), and the simulation's goals. Denser urban areas often have higher vehicle counts, while suburban or less populated areas use lower values. In practice, the number of vehicles is chosen based on a balance between real-world traffic patterns and computational resources for the simulation.  
By incorporating Kerberos, VANET systems benefit from improved security through efficient, scalable, and tamper-resistant authentication protocols. Kerberos is a secure protocol that enables mutual authentication between entities, reducing the risk of impersonation attacks. It uses a ticket-granting mechanism, requiring only one communication with the Key Distribution Center (KDC) for a ticket. Kerberos timestamps each ticket, preventing reuse by malicious actors. It supports large networks with multiple entities, making it ideal for VANET environments with numerous vehicles and infrastructure nodes.  
In our proposed system, we used the AES-128 encryption technique to encrypt the authentication message. This brings several distinct benefits instead of using ECC encryption, which is used by most of the literature [14; 15; 50; 51; 16], except for [13], which also considers AES encryption. AES is a faster, simpler, and resource-efficient symmetric encryption method compared to ECC. It uses the same key for both encryption and decryption, making it ideal for real-time applications in VANETs. Additionally, AES requires less computational power, making it suitable for low-power devices and real-time traffic updates.  
The integration of blockchain with VANET requires careful analysis of gas and cost implications. The gas values also indicate the real cost that will be spent to execute the system. Gas value analysis can be beneficial for companies considering using a blockchain-based system. Optimizing smart contract code is crucial for real-world applications. A lightweight design reduces computational burden, making it viable for real-time operations in VANETs. Unlike most of the literature [12; 14; 15; 50; 51], our system analysis of gas and cost implications demonstrates its practicality.  
Fast authentication is crucial in VANETs due to the high mobility of vehicles. Minimizing authentication delay ensures secure access and rapid information exchange. High handover delay can cause communication interruptions or network disconnections. Reducing end-to-end delay is essential for real-time communication. Our literature has analyzed all three possible delays (authentication delay, handover delay, and end-to-end delay) to ensure practicality, while some studies [12; 15; 50] focus only on end-to-end delay, and some others [13; 16] investigate only authentication delay.