Abstract: While Internet of things (IoT) technology has been widely recognized as an essential part in our daily life, it also brings new challenges in terms of privacy and security. In view of the limited resources, large number of connections and strong dynamics of the devices in the Internet of things, the traditional centralized access control technology is not fully applicable, and how to achieve secure and efficient access control authorization in the IoT environment has become an urgent problem to be solved. In this regard, a distributed architecture based on hierarchical blockchain for Internet of Things (DAHB) is proposed, which includes device layer, edge layer and the cloud layer. In this architecture, we combine the advantages of blockchain technology to realize flexible, dynamic and automatic access control for IoT devices based on ABAC model in the domain and across the domain by means of smart contract. At the same time, the credit value and honesty are added to the attribute metric to dynamically evaluate the trust relationship between different domains and devices. The theoretical analysis and experimental results show that this scheme is more effective than the existing schemes in solving the requirements of lightweight, flexibility, fine-grained and security in Internet of things (IoT)access control.

Key words: Internet of things (IoT), blockchain, access control, trust, smart contract