# Blockchain-Based Secured Access Control in an IoT System
## 4 Related Work
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Reference** & **Advantages** & **Limitations** \\ \hline FairAccess [10] & The Pseudonymous technique is used to ensure the privacy of the users. & \begin{tabular}{c} Produces possible delays due to owner communication as authorization occurs through tokenization. \\ \end{tabular} \\ \hline Novo [8] & It utilizes managers, who are responsible for registering IoT devices and verifying them. & \begin{tabular}{c} Even though this solution gains scalability as a result of distributing query permissions via management hubs, it could encounter security threats if the manager is malicious. \\ \end{tabular} \\ \hline [PERSON] [12] & It does not use Proof of Work (PoW) consensus validation blocks as all IoT devices in the smart home tier are controlled via the miner. & \begin{tabular}{c} The proposed architecture is smart home application based, not a generic solution and may not be well suited to other IoT use cases. Moreover, this mechanism does not support self-enforced access control policies. \\ \end{tabular} \\ \hline [PERSON] [27] & The architecture addresses security and privacy issues by incorporating Mandatory Access Control policies in the cloud and BYOD environments delicately and securely with an independent platform. & It does not protect the integrity of the transmitted messages. \\ \hline [PERSON] [13] & The infrastructure established an ECC-based security key and uses the RBAC authorization method based on the user’s role. & The solution is highly centralized and therefore is not well suited to the IoT environment due to the distributed nature of IoT networks. \\ \hline [PERSON] [14] & It improved efficiency at a minimal communication cost by incorporating secure session key establishment, maintaining user anonymity and mutual authentication. & \begin{tabular}{c} Role-Based Access Control and credential-based access control models cannot be directly applied to IoT due to their inherited disadvantages. \\ \end{tabular} \\ \hline [PERSON] [15] & It uses hybrid Role-Based Access Control and Attribute-Based Access Control models to target large-scale dynamic users. It resolves policy conflicts and redundancy. & \begin{tabular}{c} Granting permissions and role management is still the responsibility of the administrator in the proposed model. \\ \end{tabular} \\ \hline [PERSON] [18] & It is based on a UML conceptual model to define privacy policy definitions and data quality assessment in order to lay the foundation for the development of a secure and private IoT-based environment. & The data integrity and security of the transmitted messages must be ensured. \\ \hline NTT Innovation Institute [23] & It used a Mandatory Access Control mechanism for securing an IoT framework and hosting policy administration points by forcing unauthorized communications to be shut down. & \begin{tabular}{c} The integrity of transmitted messages is not fully protected. \\ \end{tabular} \\ \hline [PERSON] [18] & It eases the administration of policies by incorporating attribute-based control policies. & \
\begin{tabular}{c} Transmitted messages are not fully protected (in terms of their integrity) against illegal modifications. \\ \end{tabular} \\ \hline [PERSON] [24] & It eases users to purchase a token from the network owner in order request the sensor data, which are delivered after the verification of the token. It uses a distribution token reuse detection mechanism to avoid the reuse of tokens, which would enable unauthorized access. &
\begin{tabular}{c} The main work focused on privacy preservation and did not consider fine-grained access control policies for end devices. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summary of the advantages and drawbacks of the related works. overheads. Furthermore, public blockchains are not suitable for resource-constrained IoT devices, as they demand high computational power for mining processes.