## 1 Introduction
Moreover, the blockchain empowers all network participants to engage in the maintenance of the ledger, thereby promoting a transparent and tamper-proof ecosystem [19]. In essence, the blockchain stands as a vanguard technology that propels VANETs into a new era of security and reliability. It ensures that vehicular communications are not only secure, but that they also conducted within a framework that is inherently resistant to cyber attacks. By integrating blockchain solutions, VANETs evolve into more resilient, transparent, and decentralized networks that are capable of withstanding the escalating threats in today's cybersecurity landscape [20]. In this context, this paper proposes a security architecture for the VANET using blockchain technology. Traditional security solutions, such as public key infrastructure (PKI), have limitations when applied to the VANET, particularly due to the high mobility and short-term connectivity of the network. Previous reputation management models have attempted to address these challenges but have faced unresolved issues [21]. In addition, although VANETs can benefit from Internet of Things (IoTs) technologies to communicate connected remote devices [22], the diversity of formats, resolutions, information sources, and mediums in VANETs makes interactions in these networks a complex task [23]. The use of blockchain technology not only maintains the security and accountability of vehicle interactions, but also facilitates the tracking of vehicle position and movements. Our solution aims to improve the capacity for successfully detecting attacks against the VANET and attacks from malicious nodes, thereby ensuring both efficient and secure vehicular communications. Our solution aims to increase the success rate in detecting attacks against the VANET and attacks from malicious nodes. Specifically, this architecture generates secure hashes for each vehicular interaction and allows for the verification of these by each node in the network, thereby minimizing the possibility of illegal activities within the VANET system. Our paper presents several key contributions that collectively address the critical issues surrounding vehicular ad hoc networks (VANETs). These contributions introduce advancements in multiple domains within the VANET ecosystem. Specifically, they include the following:  
* Architecture of Security for VANET: Our proposed architecture leverages blockchain technology to significantly enhance the security of VANET systems. It provides a robust framework for secure and reliable communication among vehicles. * Generation of Secure Hashes for Vehicular Interactions: We introduce a novel method for generating secure hashes for each vehicular interaction. This method ensures the integrity and authenticity of the interactions, thereby contributing to a safer and more reliable network. * Network-Wide Verification and Mitigation of Illegal Activities: Our architecture enables each node in the VANET network to verify the interactions through the generated hashes. This decentralized verification process bolsters the overall security of the system, thereby effectively minimizing the potential for illegal activities. And these advances have different practical implications in real-life scenarios. For example, they include the following:  
* Enhanced Security: The architecture significantly elevates the security level in VANETs by leveraging a dual-layer blockchain approach, thereby ensuring the authenticity and integrity of vehicular communications, which is critical for applications like emergency response and traffic management. * Improved Efficiency: By reducing the observation errors in reputation assessment [24], the system enhances the overall network efficiency, which is crucial for real-time applications such as collision avoidance systems and dynamic traffic light control.