## 3 Auto-Insurance Systems Based on Cloud or Blockchain
### Hybrid Auto-Insurance
The benefits and issues in the aforementioned hybrid (i.e., cloud- and blockchain-based) vehicle insurance options are listed in Table 3. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Ref** & **Advantages** & **Issues/Limitations** \\ \hline
[49] & A lightweight object application blockchain framework was proposed, which integrated DF processes and data privacy to provide efficient vehicle-related digital investigations. The stored data were only disclosed to an authorized party. & Block4 forensic (B4F) was proposed with 100\% support by a VANET blockchain; however, practically speaking, this is not realistic. Therefore, it is necessary to find out how much a blockchain system’s performance is affected by the nodes’ mobility in a VANET. & Block4 forensic (B4F) was proposed with 100\% support by a VANET blockchain; however, practically speaking, this is not realistic. Therefore, it is necessary to find out how much a blockchain system’s performance is affected by the nodes’ mobility in a VANET. & B4F employed blockchain to achieve data integrity; therefore, it was prone to selective data sharing and data alterations, because the vehicle was in charge of determining which data were used as evidence to determine liability, and the integrity of the sensors that contributed the data was not considered. \\ \hline
[50] & The suggested system used crypto IV-TP and was based on rewards that provided records in case of accidents. The data were validated and audited using a smart contract. Vehicles were linked to the blockchain and had a special crypto number. Consistency in BC was guaranteed through distributed consensus mechanisms. & The strategy was not ideal for large datasets, such as multimedia data, because it would raise the cost of the vehicle’s calculations and storage, which would eventually decrease system performance [53]. A malicious vehicle may purposefully transmit misleading information and confuse other vehicles to exploit the vulnerabilities of VANETs. \\ \hline
[51] & A permissioned BC-based reputation structure was introduced to prevent the spread of misleading information across the network. The records of automobiles were only handled by trusted parties. & The system was complicated as a result of the hybrid cloud environment, which consisted of both internal and external clouds. \\ \hline
[52] & Designing and implementing a blockchain-based solution to prevent the NHIS from going bankrupt was the goal of this effort. & The authors claimed that “the system achieves its objectives because all the write, delete, and modification operations were successfully executed in the worldstate and blockchain systems”, but this was unclear, because blockchain does not permit alterations or deletions. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Advantages and limitations of hybrid (cloud- and blockchain-based) auto-insurance solutions. Thus far, we have identified and mentioned the primary issues (and challenges) related to blockchain- and cloud-based auto-insurance. The relevant studies are compared in Table 4 on the basis of the aforementioned issues and challenges. Table 4 demonstrates that storage (rather than security) is the primary focus of most research on cloud-based auto-insurance. Many insurance organizations consider using the cloud for storage to be fairly easy, because they do not have to worry about managing and expanding their storage. Additionally, cloud platforms have eliminated the requirement for local devices and many other services. Many organizations entirely rely on cloud service providers to keep their data secure and accessible. However, cloud infrastructures still face several internal and external threats to data integrity, and even well-known cloud providers suffer from outages and data loss [54]. In order to maintain their clients' faith and confidence, cloud service providers generally hide the issues with their cloud storage servers. Integrity issues in cloud computing can occasionally be caused by architectural problems [55].