Towards Verifiable Mutability for Blockchains

TL;DR

This paper proposes a novel blockchain structure that allows for controlled mutability, enabling block removal while preserving verifiability, thus addressing privacy and legal challenges without depending on specific consensus algorithms.

Contribution

It introduces a blockchain design that supports verifiable mutability, applicable to both permissioned and permissionless systems, enhancing privacy and legal compliance.

Findings

Supports removal of specific blocks without losing verifiability

Compatible with various consensus algorithms

Addresses privacy and illegal content challenges

Abstract

Due to their immutable log of information, blockchains can be considered as a transparency-enhancing technology. The immutability, however, also introduces threats and challenges with respect to privacy laws and illegal content. Introducing a certain degree of mutability, which enables the possibility to store and remove information, can therefore increase the opportunities for blockchains. In this paper, we present a concept for a mutable blockchain structure. Our approach enables the removal of certain blocks, while maintaining the blockchain's verifiability property. Since our concept is agnostic to any consensus algorithms, it can be implemented with permissioned and permissionless blockchains.