# Secure Trust-Based Blockchain Architecture to Prevent Attacks in VANET
## 4 Proposed Blockchain in VANET  
Many academicians and researchers are drawn to blockchain technology for its enormous benefits to be gained in vast fields, including academics, finance, medicine, and banking. To be precise, blockchain is a technology that is technically comprised of an unlimited number of blocks that are connected in a sequential order to form a blockchain. As this technology is potentially beneficial for expertise in vast fields, it has also gained the interest of many in resolving critical information dissemination issues in VANETs. Bitcoin cryptocurrency is the underlying support of blockchain technology that emerges from the decentralization and distribution of a computing paradigm that has the ability to provide privacy and security in peer-to-peer (P2P) networks [35]. In the VANET environment, this technology is a vital part that helps in managing the ground truth of information for automobiles due to the fact that any automobiles in the system can access the past event lists and its information if it is placed in the public blockchain. The proposal is to generate a scheme whereby the trustworthiness of node and message passing in VANET is guaranteed by placing them in a public blockchain to act as a ground truth for other automobiles. The application of an existing blockchain to the VANET system is not sufficient, as event messages as a transaction form are adopted instead of the bitcoin transaction for the cryptocurrency feature. The reason for the variation made to the transaction is to ensure the suitability of features for the VANET system as an assurance of providing security for critical information dissemination and resolving the VANET issues. The variation method adapted adds new blocks based on event messages, similar to transactions in bitcoin, apart from the hashing sequences of blocks to be connected in chronological order to the blockchain. The scalability and timeliness of message dissemination is ensured in this system by implementing a local blockchain with independent chains from different geographical regions. A public blockchain is considered to store and manage all the node and message trustworthiness information given in a geographical region. Based on the type of blockchain, which could be either public or private, a different set of blockchain consensus mechanisms are offered. Therefore, the security and scalability level of the blockchain also depends on the vital role played by the consensus mechanisms. For simplicity, Table 1 shows all the notations, with their descriptions, used throughout the paper. \begin{table}
\begin{tabular}{c c} \hline \hline
**Notation** & **Description** \\ \hline V\({}_{i}\) & Vehicle \(i\) \\ PU\({}_{i}\) & Public Key of V\({}_{i}\) \\ PR\({}_{i}\) & Private Key of V\({}_{i}\) \\ C\({}_{i}\) & Certificate of V\({}_{i}\) \\ CertBC & Certificate Blockchain \\ RevBC & Revocation Blockchain \\ ID\({}_{i}\) & Identity of V\({}_{i}\) \\ M\({}_{i}\) & Message \(i\) from Vehicle \(i\) \\ TrustBC & Trust Blockchain \\ P(\(e\)/c) & Probability of Event \(e\) \\ MeshBC & Message Blockchain \\ O\({}_{r}\) & Set of Offsets of Road Side Unit \(r\) \\ S\({}_{R}\) & Hash Threshold of RSU \(r\) \\ RSSI\({}_{i}\) & Relative Signal Strength Indicator Value of Vehicle \(i\) \\ t\({}_{i}\) & Timestamp of Vehicle \(i\) \\ h\({}_{n}\) & Hash Value of block \\ \hline \hline \end{tabular}
\end{table} 
Table 1: List of notations and description used. A simple blockchain would not be suitable for the VANET issue discussed in this study. Hence, an improvised type of blockchain mechanism with some feature adaptation is proposed as a solution. Figure 2 depicts the improvised packet structure with the integration of a blockchain that was used for a secure communication by VANET components.