RPChain: Regulatable Privacy-Preserving Group Data Sharing Based on Consortium Blockchain

Due to the transparency and immutability of consortium blockchain systems, researchers proposed network analysis and clustering algorithms to achieve deanonymization of user identity and reveal transaction patterns. The exposure of user privacy has motivated further research on privacy-enhancing data sharing schemes, which poses additional difflculties for regulation. In this paper, we propose RPChain, a framework that allows users to share data anonymously and cuts the link between data sender and data receiver via ring signature and broadcast. Combining secret sharing and proxy re-encryption, RPChain allows identity privacy and transaction privacy to be revealed only if a data transfer is determined to be illegal by a vote. We utilize a thresholding mechanism to spread the computational overhead across different authorities and adopt data indexing for efficiency. Experiments show that RPChain can handle large throughput and data size. Security analysis shows the promise of RPChain in ensuring identity and transaction privacy.