SynergyChain: A Multichain-Based Data-Sharing Framework with Hierarchical Access Control

With customization of demands and functionalities, diverse blockchain systems are integrated with IoT in different application scenarios, forming a multichain environment. Multichain interoperability has become a crucial emerging issue, i.e., different blockchain systems are difficult to interact with each other credibly and efficiently. It further leads to isolated data islands across multichain. Therefore, it is of significant importance to facilitate data sharing among multichain systems. Toward achieving this, there are two main challenges. First, data across multiple blockchains must be shared reliably to meet the tamper-proof merits of blockchain technology. Second, we must control the data access process in a fine-grained way to protect sensitive data and user privacy. This article proposes SynergyChain, a multichain framework to enable reliable data sharing with controllable data access. By aggregating the data from multiple blockchains and reorganizing it in SynergyChain, we can achieve data reliability with the verification. Meanwhile, SynergyChain provides hierarchical access control based on smart contracts, making access control automated and credible. Experiments show that SynergyChain can support data sharing reliably and efficiently and reduce data query latency compared with multichain data requesting sequentially.