PRBCP: Publicly Redactable Blockchain With Off-Chain Reputation-Based Consensus Protocol

Blockchain is renowned for its immutability, a feature that ensures recorded data cannot be modified or deleted. However, malicious entities can exploit this immutability to permanently embed objectionable data. Moreover, the immutability of blockchain can conflict with the “right to be forgotten” provision in the privacy protection laws of the GDPR. Therefore, a seminal redactable blockchain solution is proposed to address the above problem. Recently, one of the primary focuses in redactable blockchain solutions is the design of global editing permission control. The design leverages the consensus voting mechanism, with its core objective being to prevent excessive centralization of editing power, thereby preserving the decentralized nature of blockchain technology. Meanwhile, such schemes exhibit the following phenomena: (i) the members of the editorial decision-making group are fixed and unchanging, and (ii) blockchain nodes display lazy voting behaviors during the editorial voting process. Considering these factors, we introduce a Publicly Redactable Blockchain scheme with an off-chain reputation-based Consensus Protocol $(\mathcal {PRBCP})$ . In this scheme, any node in the blockchain network has the opportunity to become an editorial node and perform editing operations. We design a reputation-based off-chain editorial voting consensus protocol leveraging the threshold signature scheme, which enables dynamic updates to the editorial decision-making group membership and enhances nodes’ participation in editorial voting. In addition, we conduct rigorous security proofs and experimental efficiency analyses for our scheme. The results demonstrate that the $\mathcal {PRBCP}$ is both secure and efficient. Finally, we instantiate our scheme as a redactable medical blockchain (RMB) system for storing electronic medical records (EMRs).