## 2 Related Work
### Access Control  
On the basis of the current research, the access control model in industrial internet of things can be divided into the following categories: Attribute-based access control (ABAC), role-based access control (RBAC), and access control technology based on usage control (UCON), based on capabilities and fuzzy logic [33].  
Based on the RBAC and ABAC models, integrating context-related information and entity attributes, a variety of access control models based on RBAC or ABAC have emerged in IoT. The access control models combined some new features under IoT environment and improved the traditional access control models [34].  
Based on UCON, many scholars have studied the access control model in the Internet of Things. UCON adopts a series of restrictions to ensure the security of access control. The access control architecture is based on a service-oriented architecture and includes the following components: Devices, services, trust management centers, and usage control access control models. The usage decision of the usage control model is determined by the attribute values of several factors such as device, service, condition, responsibility, and authorization. To ensure the security of the use control, the usage control model introduces seven sub-models related to authorization, seven responsibility-related models, and two condition-related models. However, these are still insecure in the IoT environment [35]. And they lack accurate representation of authorization process and precise definition under IoT environment.  
There is also the problem that the current authorization framework such as RBAC and ABAC cannot effectively provide an easily scalable and manageable access control mechanism to provide dynamic scalability with many intelligent terminals and interactive services, which also cannot support access control requirements of distributed IoT environments. Based on the principle of layering, the resources and sensing layer can be hierarchically divided. Then, the corresponding access control scheme is designed according to the layering. Because traditional access control schemes cannot meet the security, privacy, or customized consumption and data diversity requirements of the perception layer in IoT, authors in the literature [27] propose hierarchical access control schemes. In the schemes, the user only needs to simply calculate a part of the user's single key to access the corresponding level.  
Recently, [PERSON] et al. proposed an authentication and access control scheme for industrial 4.0 based on blockchain [36; 37]. The schemes utilize attribute-based digital signature and a certificateless multi-receivers encryption mechanism. However, the two cryptographic mechanisms require high computational power. [PERSON] et al. achieved the anonymity and security of IoT data by deploying Fairaccess in UTXO to implement blockchain-based access control [38]. [PERSON] et al. released the transfer of rights in the blockchain, the access control rights are passed through the blockchain transaction, and the access resources can be easily passed [39]. However, their study only focuses on  
Figure 2: Architecture of edge computing.  
the security of the framework and does not study the sensor capacity. So, the proposed schemes cannot be used on resource-constrained terminals.