A Correctable Public Blockchain

Abstract

A key property of current blockchain solutions is the immutability of data stored in the blockchain. While this is a desired feature e.g. for crypto currencies, it can be a show stopper for other use cases that still require ex-post correction or removal of stored data. Existing proposals for redactable blockchains address this issue, but support the correction of specific types of stored data only. To overcome these limitations, we propose and introduce a correctable blockchain architecture that supports correction of arbitrary data. The proposed solution uses a consensus-enforced voting mechanism for decentralized decision making on requested data corrections. Information on applied corrections is stored in a second chain, which ensures that the corrected chain can still be validated successfully. We have verified the security of the proposed correctable blockchain architecture by means of a detailed security analysis. Furthermore, we have evaluated the proposed solution by means of a first reference implementation, which demonstrates the solution's feasibility. First experiments conducted with this reference implementation indicate that the added data-correction functionality has only negligible impacts on the overall performance.