Achieving Fine-Grained and Flexible Access Control on Blockchain-Based Data Sharing for the Internet of Things

The traditional centralized data sharing systems have potential risks such as single point of failures and excessive working load on the central node. As a distributed and collaborative alternative,approaches based upon blockchain have been explored recently for Internet of Things(IoTs). However, the access from a legitimate user may be denied without the pre-defined policy and data update on the blockchain could be costly to the owners. In this paper, we first address these issues by incorporating the Accountable Subgroup Multi-Signature(ASM) algorithm into the Attribute-based Access Control(ABAC)method with Policy Smart Contract, to provide a finegrained and flexible solution. Next, we propose a policy-based Chameleon Hash algorithm that allows the data to be updated in a reliable and convenient way by the authorized users. Finally, we evaluate our work by comparing its performance with the benchmarks.The results demonstrate significant improvement on the effectiveness and efficiency.