## 4 Findings
### Other Works
#### 4.7.5 Mobile IoT Applications
\begin{table}
\begin{tabular}{l c c} \hline \hline \multirow{2}{*}{**Ref \#**} &
\begin{tabular}{c} **Future Works** \\ **(Open Issues)** \\ \end{tabular} & **Notes** \\ \hline \multirow{3}{*}{[104]} & & \(\star\) Low latency \\  & & \(\star\) High feasibility \\  & & \(\star\) Enhanced image size \\  & & \(\diamond\) Privacy concerns are still an issue when implementing in real-time environment \\ \hline \multirow{3}{*}{[105]} & & \(\star\) The proposed architecture is not limited to healthcare domain only \\  & & \(\star\) Efficient and pairing-free authentication scheme \\  & & \(\star\) Guaranteed user anonymity with satisfied security requirements \\  & & \(\diamond\) Certain security properties and efficiency metrics can be improved \\ \hline \multirow{3}{*}{[106]} & & \(\star\) The proposed system offers confidentiality, integrity, privacy, and access control \\  & & \(\diamond\) The authors suggests adding a fog layer between different system entities in order to process and filter the data \\ \hline \multirow{3}{*}{[107]} & & \(\star\) New consensus protocol is introduced while maintaining the system’s robustness, efficiency, and adaptability \\  & & \(\star\) The proposed consensus protocol requires less computational cost than PoW and PoA \\  & & \(\diamond\) Overall computation cost is not considered when this approach is implemented \\ \hline \multirow{3}{*}{[108]} & & \(\star\) Reduces computational cost \\  & & \(\star\) Enhanced node transactions performance \\  & & \(\star\) This design offers provenance, transparency, security, and integrity \\ \hline \multirow{3}{*}{[109]} & & \(\star\) This work promises higher security levels and lower execution time \\  & & \(\star\) This approach achieves consistency, security, availability, integrity, and transparency \\  & & \(\diamond\) Tested for medical supply chain-based scenario only \\  & & \(\diamond\) No description of encryption and decryption of OTH \\ \hline \multirow{3}{*}{[110]} & & \(\star\) As compared to other models, DSMAC overcomes the others as it provides scalability, sustainability, data \\  & & \(\star\) privacy, and emergency case \\  & & \(\star\) DSMAC includes access control methods such as identification, authentication, and authorization \\ \hline \multirow{3}{*}{[111]} & & \(\star\) Using such an access control approach provides a non-repudiation feature and allows users’ preferences and device policies to be preserved without tampering. \\ \hline \multirow{3}{*}{[112]} & & \(\star\) The authors included the advantages and several important remarks that can be added to the proposed \\  & & \(\star\) approach to improve its performance \\  & & \(\star\) Flexibility to use all encryption algorithms \\  & & \(\star\) Intrusion prevention \\  & & \(\star\) Adding a new layer of security \\  & & \(\diamond\) This approach will be considered useless if the database is corrupted in any form \\  & & \(\diamond\) Scalability issue: the processing performance decreases as the number of smart devices increases \\ \hline \multirow{3}{*}{[113]} & & \(\star\) Supports dynamic auditing \\  & & \(\star\) satisfies the public verification and correctness \\  & & \(\star\) The used storage method offers many advantages such as reducing cost \\ \hline \multirow{3}{*}{[114]} & & \(\star\) Anti-attack capability (10 types of attacks) \\  & & \(\star\) When this system is implemented in certain industries, its performance must be improved, as well as the risk of \\  & & \(\ privacy\) leaks must be addressed. \\ \hline \multirow{3}{*}{[115]} & & \(\diamond\) Single points of failure (due to using smart contract proxy and MQTT) \\  & & \(\diamond\) Reduced throughput \\  & & \(\diamond\) Increased latency by the evaluation scenario \\ \hline \multirow{3}{*}{[116]} & & \(\star\) This approach is not implemented and evaluated yet \\ \hline \multirow{3}{*}{[117]} & & \(\star\) This approach is not implemented and evaluated yet \\ \cline{2-2}  & & \(\star\) This approach offers better scaling than a single Ch blockchain system \\ \cline{2-2}  & & \(\star\) Massive resource requirement \\  & & \(\diamond\) IoT device integrity mechanism is required \\ \hline \multirow{3}{*}{[119]} & & \(\star\) Enhanced scalability and flexibility \\  & & \(\diamond\) It might introduce large communication overhead \\ \hline \multirow{3}{*}{[120]} & \(\star\) & \(\star\) High extension ability \\  & & \(\star\) Ability to handle misbehavior \\ \hline \multirow{3}{*}{[121]} & & \(\star\) Reduced processing time \\  & & \(\star\) Low energy consumption \\  & & \(\diamond\) Requires extra cost due to cloud usage \\  & & \(\diamond\) Low scalability \\ \hline \multirow{3}{*}{[122]} & & \(\star\) Decreases processing time and bandwidth compared to traditional blockchains \\  & & \(\diamond\) Using DTC in small networks can make the network vulnerable to Sybil attack \\ \hline \hline \end{tabular}
\end{table}