## 2 Related Work
### Blockchain Solutions for VANETs, Trust Models, Cyber Attacks, and Mitigation Strategies
Bayesian inference has shown to be particularly suitable for the quantitative judgement of interactive trust in the VANET context [49; 50; 51; 52]. Other authors have emphasized the pressing concern of cyber attacks on data stored in cloud servers [53]. Or, they have pointed out the vulnerability of VANETs to these attacks due to the critical and sensitive nature of the data they handle [54]. A decentralized approach using blockchain technology was proposed to safeguard this data [23]. By employing cryptographic techniques, the information was encrypted, thus bolstering its confidentiality and anonymity [55]. However, limitations were also observed, mainly regarding scalability and the high computational power required for these cryptographic processes [56]. The focus shifted towards the centralization of data management in VANETs, which traditionally relies on systems maintained by vehicle service providers [57; 58]. The risks associated with such a setup were recognized, including system failures and protection disagreements [59; 60]. To address these concerns, a blockchain-based architectural design was proposed that employs sovereign identity for enhancing the security of data and uses a multitier, capability-based authentication process [61; 62]. Although promising, the research also highlighted the need for robust standardization to ensure the seamless integration and interoperability of the proposed system [63]. In response to the exponential rise in wireless connected devices [64], the limitations of cloud computing in effectively addressing associated security concerns were pointed out [65]. A blockchain-based structure was proposed that was specifically designed for VANETs, thus focusing on resolving performance and scalability issues [23]. The results showed an improvement in data management and security. However, concerns about the implementation complexities of integrating blockchain technology into existing VANET systems were also raised [6]. The primary feature of the blockchain that benefits VANETs is its decentralized nature, which eliminates the need for a central authority, thereby reducing the risk of single-point failures and potential bottlenecks in data flow. Additionally, the transparency and immutability of blockchain technology ensure the integrity of the data, thereby making it resistant to tampering and forgery [28]. Figure 1: Blockchain-based architecture for VANETs. Various security issues like forgery, denial-of-service, and smart card theft threats that plague VANETs were tackled [44]. A blockchain-enabled authentication and authorization system for VANETs was presented, which efficiently managed privacy and information integrity [66]. Despite the contributions, the need for further optimization to improve the system's efficiency was acknowledged, especially under high network load conditions. Finally, it was explored how VANETs rely on a third-party financial intermediary to share information electronically [67]. A paradigm shift towards blockchain was argued for, thereby eliminating the need for a central authority and fostering a more transparent and trusting environment [34]. A blockchain-enabled platform was developed to facilitate information exchange between domains [66]. However, the necessity of efficient consensus algorithms to manage the increased network traffic effectively was also highlighted [68]. Nervetherless, the combination of VANETs and blockchain technology has great potential to address the various security challenges faced by VANETs [69].