IvyRedaction: Enabling Atomic, Consistent and Accountable Cross-Chain Rewriting

Blockchain rewriting has become widely explored for addressing data deletion requirements, such as error data deletion, space-saving, and compliance with the “right-to-be-forgotten” rule. However, existing approaches are inadequate for handling cross-chain redaction issues, in facing with the increasing need for inter-chain communication. In particular, transaction rewriting on a blockchain might have relevant effects on the states of other blockchains. The cross-chain interoperability results in inter-chain transactions with more complex dependency relations. The issues pose new challenges to achieve rewriting consistency, for example, ensuring the rewriting of related transactions when a transaction is being modified, and achieve atomic rewriting, whereby two cross-chain transactions must either all, or neither, be processed. This article introduces a cross-chain solution IvyRedaction, with an emphasis on customizing a decentralized intermediary for generating and maintaining global cross-chain redaction states and transaction dependencies. The article proposes a novel cross-chain state mapping method with rollback rules, as well as customized block structures and verification algorithms, to address the aforementioned issues. Proof-of-concept experiments are conducted to demonstrate the feasibility of the proposed framework.

I. Introduction

Blockchain technology has been envisioned as a promising paradigm that will give rise to the reconstruction of the underlying Internet. It is regarded as a flagship technology to realize trustful public bulletin boards, bringing immutability and transparency into practical scenarios, without relying on any trusted party. Over the last decade, we have witnessed several interesting new systems that are constructed based on the blockchain and smart contracts, e.g., cryptocurrencies [1], [2], supply chain [3], data storage [4], [5], [6], distributed learning [7], digital right management [8], [9] and network slicing service [10].