## 4 Comparison of Our Design Approach with the Existing Literature: Potential Benefits  
In this section, a comparison study is performed among the architectures based on BCT and ML in the literature and the one proposed in this paper from a design perspective. Table 2 summarizes this comparison. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Architecture** & **Description** & **Smart Contract Data Structure** & **Design Approach: Discussion** \\ \hline \multirow{6}{*}{[PERSON] et al. [8]} & The authors propose an IIoT & & Authors suggest a solution based on ML to detect DDoS, malware, and advanced persistent threats in the edge and fog computing. The architecture can be enforced with BC to provide traceability and integrity. \\  & system architecture based on & & ML to detect DDoS, malware, and advanced persistent threats in the edge and fog computing. The architecture can be enforced with BC to provide traceability and integrity. \\  & & & ML to detect DDoS, malware, and advanced persistent threats in the edge and fog computing. The architecture can be enforced with BC to provide traceability and integrity. \\ \hline \multirow{6}{*}{[PERSON] et al. [12]} & The GridMonitoring system is based on four layers for smart grid network applications. & Smart contract is employed for the recording of the violations on the smart meter, data on the smart grid network and the state of the smart meter. & The benefit of the proposed solution beside the BCT is the usage of an authentication mechanism and data center to save all information to report any violations. The solution employed a classical smart contract database to report any violations that can be the object of an injection attack. The solution can be enhanced with an ML-based solution to prevent injection and XSS attacks. \\ \hline \multirow{6}{*}{[PERSON] et al. [13]} & The architecture is composed of perception, communication, Blockchain-composite and industrial applications layers. & The survey paper exhibits the life cycle of smart contracts including creation, deployment, execution and completion. & The architecture is highly structured. BC-composite layer includes data, consensus and network sub-layers. Merging data and network in one layer can lead to serious privacy violations in case of MitM attacks. \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Proposed architecture based on BCT/ML vs. literature: a comparison of design approaches. The conclusion of this comparison is that our design approach outperforms other architectures in terms of decentralized architecture and the capability to detect the most dangerous attacks in IIoT networks such as DDoS, injection, brute force and XSS attacks by proposing a smart contract data structure and algorithm for sensor access control system. In addition, in our architecture, the BC tools and transport layer provides data integrity by offering a digital signature. Furthermore, the advanced service layer provides traceability by adding pertinent authentication data inside the BC. Table 3 presents the comparison between our system and similar ones in the literature in terms of security metrics such as integrity, availability, immutability, confidentiality and privacy. In our model, integrity is considered in the BC tools and transport layer through a digital signature generated by the sender private key and added to the sender authentication request to the desired sensor. Availability and immutability are granted thanks to the inherent features of BCT. Confidentiality and privacy is preserved by using a symmetric key encryption for all messages transferred across the IIoT network. The next section describes a two-step experimental study that is aimed to illustrate these potential benefits.