A Conflict-Free Redactable Blockchain

To cope with the challenges that posed by illegal data on the immutable blockchain, and to meet the requirements of privacy regulations, the redactable blockchains are proposed. The biggest shortcoming of the state-of-the-art redactable blockchain protocols is that they fail to consider the appearance of multiple conflicting redactions at the same time. When the protocol faces multiple conflicting requests for a specific block submitted almost simultaneously, their method will lead to conflicts. We put forward a redactable blockchain protocol that packages requests into a conflict-free set for vote-based consensus to eliminate the possibility of two different edited versions of the chain and ensure the consistency of the system. Moreover, our protocol, unbinding the redaction processing from the extension of the blockchain, can be easily integrable in blockchain systems based on proof of work and proof of stake. Furthermore, our protocol, resisting against a fully adaptive adversary, confirms the edited blocks at a constant rate.