A Blockchain-Based Trustable Framework for IoT Data Storage and Access

As the use of Internet of Things (IoT) devices is increasing dramatically, it is necessary to provide a trustable framework when IoT data are stored and used inside or outside IoT devices. Blockchains and smart contracts provide solutions to construct trustable environments in data storage and access. Unfortunately, current blockchain technology only suits for situations that a small or medium amount of data is stored and used, but it has a very low performance when a large amount of data gathered by IoT devices needs to be stored and accessed. This paper proposes a three-layer blockchain-based trustable framework for IoT data storage and access. In the framework, users, roles, permissions, data objects, and their relationships are formally defined. Based on these definitions, smart contracts with role-based access control (RBAC) model are developed. Additionally, a snapshot mechanism is designed to collect IoT data in order of time stamps and put it into files stored in the inter-planetary file system (IPFS). We developed a prototype of supply chain tracing system on Ethereum and IPFS for feasibility verification and performance evaluation of the proposed framework. The framework not only guarantees data integrity in storing IoT data, but also ensures data confidentiality when the IoT data is used. Moreover, simulation results illustrate that the prototype system has high performances in time, space, and gas consumption.