## 9 Discussion  
### Challenges, Open Issues, and Future Research Directions for EIAVs  
The domain of autonomous vehicles (AVs) remains in its growth phase, laden with an abundance of sensitive information and fresh technical hurdles. The enormous breadth and complexity of the topic render it multifaceted terrain. This is further compounded by the current scarcity of comprehensive global standards that guide the development, safety, and security procedures for AVs. As a result, investigating and addressing issues regarding the security and safety of AVs is not only highly intricate but also of utmost importance. As AVs continue to evolve technologically, their ecosystem is expected to broaden to include a greater number of individual devices and supplementary infrastructure. This growth is likely to bolster connectivity; however, it could simultaneously render AVs more vulnerable to a plethora of security risks. This development gives rise to critical questions and challenges that demand immediate scholarly attention. * Protection of V2X communication: Ensuring the security of vehicle-to-everything (V2X) communication is critical, as a breach in AVs might have cascading effects on connected smart infrastructure and vice versa. For instance, an attack on an electric vehicle could ripple through to the electricity grid, charging stations, and utility systems. Consequently, future research should prioritize the formulation of strong protective measures and the establishment of secure communication channels. * Synchronization of safety and security protocols: Typically, assessments of vehicle safety and security are performed separately, which leads to the creation of disparate protective measures. However, fostering a seamless synergy between safety and \begin{table}
\begin{tabular}{c c c c} \hline Description & Blockchain Platform & Authors & Year \\ \hline Fragmented ledger for forensic analysis of traffic accidents & Lightweight BC & [PERSON] et al. [155] & 2018 \\ \hline Event recording system for vehicular digital forensics & Ethereum & [PERSON] et al. [160] & 2021 \\ \hline BC-based accident responsibility identification model & Lightweight BC & [PERSON] et al. [161] & 2022 \\ \hline BC-based reputation system for AV accident forensics & Permissioned BC & [PERSON] et al. [150] & 2022 \\ \hline \end{tabular}
\end{table} 
Table 6: Blockchain applications in autonomous vehicles (AVs)—forensics applications. \begin{table}
\begin{tabular}{c c c c} \hline Description & Blockchain Platform & Authors & Year \\ \hline Data sharing in V2V using reputation and contract theory & Public BC & [PERSON] et al. [162] & 2019 \\ \hline BC-based solution for reputation management in IoV & Ethereum & [PERSON] et al. [163] & 2021 \\ \hline Two-layered AV reputation BC system & Private/Public BCs & [PERSON] et al. [164] & 2021 \\ \hline BC-based trust scheme for cellular V2X ecosystems & Consortium BC & [PERSON] et al. [165] & 2022 \\ \hline BC-based reputation system for secure V2V communications & Public BC & [PERSON] et al. [115] & 2022 \\ \hline \end{tabular}
\end{table} 
Table 7: Blockchain applications in Autonomous vehicles (AVs)—reputation and trust management. \begin{table}
\begin{tabular}{c c c c} \hline Description & Blockchain Platform & Authors & Year \\ \hline Records all necessary data for an AV forensics solution & Permissioned BC & [PERSON] et al. [155] & 2018 \\ \hline Protecting the AV identity and location privacy & IoTChain [156] & [PERSON] et al. [157] & 2018 \\ \hline Ensure safety and information integrity inside the AV & Bitcoin & [PERSON] et al. [158] & 2019 \\ \hline Data integrity by tracking the actions of AVs & Exonum platform & [PERSON] et al. [127] & 2020 \\ \hline Protection against data-tampering attacks in AV network & IOTA Tangle DLT & [PERSON] et al. [159] & 2020 \\ \hline BC key management framework and hash graphs & Permissioned BC & [PERSON] et al. [133] & 2022 \\ \hline \end{tabular}
\end{table} 
Table 5: Blockchain applications in autonomous vehicles (AVs)—data integrity and privacy.