# Cybersecurity for Blockchain-Based IoT Systems: A Review
## 6 Open Issues and Future Directions  
Blockchain technology holds great promise for securing IoT networks. However, there are several research limitations that need to be addressed to fully realize this potential. In this section, we discuss some of the most significant challenges and propose future research directions to enhance the cybersecurity of blockchain-based IoT systems. Table 3 provides a summary of these limitations and potential solutions based on the challenges outlined in Section 4 and our observations and discussions in Section 5. Table 4 highlights the benefits of combining blockchain and XAI, such as enhanced transparency, trust, accountability, compliance, and regulation in IoT systems. Each benefit is associated with specific challenges that need to be addressed, including computational and storage requirements, complexity and interpretability, privacy and data protection, and scalability and performance. The table also suggests future research directions to overcome these challenges and improve the cybersecurity of blockchain-based IoT systems. In addition to the limitations and challenges discussed above, there are several future research directions that can further improve the cybersecurity of blockchain-based IoT systems:  
(A) Scalability: One of the main challenges of using blockchain for IoT security is scalability. Current blockchain systems have limited processing capabilities, which may not be sufficient to handle the vast amount of data generated by IoT devices. Therefore, there \begin{table}
\begin{tabular}{c c c} \hline \hline
**Benefits of Integrating** & & \\
**Blockchain and XAI in IoT** & **Challenges** & **Future Research Directions** \\
**Systems** & & \\ \hline Enhanced transparency & Computational and storage requirements & Explore XAI techniques specifically tailored for blockchain-based IoT systems \\ \hline Trust and accountability & Complexity and interpretability & Develop mechanisms for interpretability and explainability in decentralized settings \\ \hline Compliance and regulation & Privacy and data protection & Investigate privacy-preserving techniques for blockchain and XAI integration \\ \hline - & Scalability and performance & Address scalability challenges in consensus mechanisms and AI algorithm performance \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Challenges and future research directions for integrating blockchain and XAI in IoT systems. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Technique** & **Limitations** & **Possible Solution** \\ \hline Public key identification & Could potentially compromise the privacy of the data being stored on the blockchain. & Use pseudonymous or anonymous identities on the blockchain. \\ \hline Single consensus algorithm & Could make the blockchain more vulnerable to attack. & Use multiple consensus algorithms. \\ \hline A single blockchain for all IoT devices & Could make it difficult to scale the blockchain to a large number of users. & Use multiple blockchains for different types of IoT devices. \\ \hline Proof-of-work consensus algorithm & Could make it difficult to process transactions quickly. & Use a more efficient consensus algorithm. \\ \hline Blockchain standards & Blockchains are still in their early stages of development, so there is a risk of security vulnerabilities. & Work to develop standards for blockchain interoperability. \\ \hline Blockchain complexity & Blockchains are a complex technology, so there is a risk that they will be difficult to use for some applications. & Develop user-friendly interfaces for blockchains. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Blockchain limitations and possible solutions. is a need for research to develop scalable blockchain systems that can handle the increasing number of IoT devices and the vast amount of data they generate. (B) Interoperability: Another challenge of using blockchain for IoT security is interoperability. IoT devices use various protocols and standards, which may not be compatible with blockchain systems.