Redactable Blockchain Based on Decentralized Trapdoor Verifiable Delay Functions

Abstract

Blockchain technology was originally designed to ensure data security and trustworthiness through decentralization and immutability. However, in recent years, the misuse of immutability limits the development of blockchain. To address this challenge, several redactable blockchain solutions have been proposed. However, existing solutions either struggle to maintain block consistency or compromise the decentralization principles of blockchain. In this paper, we present a novel redactable blockchain to address these issues. Firstly, we propose a decentralized trapdoor verifiable delay function (DTVDF) based on Wesolowski’s verifiable delay function (VDF) scheme (EUROCRYPT’2019), which distributes trapdoor shares among a group of participants. Then, we leverage the proposed DTVDF to construct our redactable blockchain solution (DTRB), where redacting blocks requires consensus from threshold nodes. Moreover, DTRB provides accountability for malicious modifications and supports aggregate verification of redacted blocks, significantly improving the efficiency of our scheme. Through experimental analysis and comparison with existing solutions, our approach demonstrates superior performance.