Redacting Transactions from Execute-Order-Validate Blockchains

TL;DR

This paper introduces a novel redactable execute-order-validate blockchain design that enhances user privacy by allowing data removal without compromising system correctness, demonstrated through implementation on Hyperledger Fabric with minimal performance impact.

Contribution

It presents the first practical design for a redactable execute-order-validate blockchain enabling user data removal while maintaining system integrity.

Findings

Supports user data removal with minimal performance overhead

Successfully implemented on Hyperledger Fabric

Maintains correctness and liveness criteria

Abstract

As user privacy gains popularity and attention, and starts to shape relations between users and service providers, blockchain based solutions thrive for ways to relax immutability without sacrificing consistency. This work answers that need and presents the first design for a redactable execute-order-validate blockchain, that grants users with the \emph{right to be forgotten}. The design is easy to adopt, as we exemplify by implementing it on top of Hyperledger Fabric. It modifies the block structure and extracts user data from the hash-chain without loosening any correctness or liveness criteria. We evaluate our design and show that it provides compliance with only a minimal performance overhead, making it a feasible add-on to any execute-order-validate blockchain system.