# Cross-Domain Access Control Model in Industrial IoT Environment
###### Abstract  
The Industrial Internet of Things (IIoT) accelerates smart manufacturing and boosts production efficiency through heterogeneous industrial equipment, intelligent sensors, and actuators. The Industrial Internet of Things is transforming from a traditional factory model to a new manufacturing mode, which allows cross-domain data-sharing among multiple system departments to enable smart manufacturing. A complete industrial product comes from the combined efforts of many different departments. Therefore, secure and reliable cross-domain access control has become the key to ensuring the security of cross-domain communication and resource-sharing. Traditional centralized access control schemes are prone to single-point failure problems. Recently, many researchers have integrated blockchain technology into access control models. However, most blockchain-based approaches use a single-chain structure, which has weak data management capability and scalability, while ensuring system security, and low access control efficiency, making it difficult to meet the needs of multi-domain cooperation in IIoT scenarios. Therefore, this paper proposes a decentralized cross-domain access model based on a master-slave chain with high scalability. Moreover, the model ensures the security and reliability of the master chain through a reputation-based node selection mechanism. Access control efficiency is improved by a grouping strategy retrieval method in the access control process. The experimental benchmarks of the proposed scheme use various performance metrics to highlight its applicability in the IIoT environment. The results show an 82% improvement in the throughput for the master-slave chain structure over the single-chain structure. There is also an improvement in the throughput and latency compared to the results of other studies. Industrial Internet of Things; blockchain; reputation; attributes; access control +
Footnote †: journal: Medical Access Control  
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Footnote 1: [[https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci)]([https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci))  
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devices in different domains not being able to access each other conveniently and share resources securely [6; 7]. The secure and reliable cross-domain access control for IIoT devices has become a hot research topic nowadays. A range of access control techniques has emerged [8] that allows for legitimate access control among different IIoT devices to prevent unauthorized and illegal access. In a traditional access control system, all access control needs to rely on a third-party server. When the third-party server is attacked or goes down, the entire access control system goes down. Since blockchain has some listed advantages, such as decentralization, security, and reliability, many scholars have incorporated blockchain technology into access control systems. Role-based access control techniques were used in [9], in which the system set different roles and assigned appropriate permissions to the roles. However, role-based access control is difficult to achieve fine-grained access control. The attribute-based access control [10] approach provides a good solution for fine-grained access by binding control policies and node attributes together. Only devices whose attribute sets satisfy the policy can access resources. However, as the complexity of industrial manufacturing grows, the policies for accessing resources have become more complex. The time required to match device attributes to resource policies is taking longer and longer. This eventually leads to higher system latency. In the process of cross-domain access control, cross-domain access is not possible due to the lack of trust among different domains. Therefore, a reliable cross-domain access platform has become especially important.