Secure replication for client-centric data stores

Abstract

Decentralized, peer-to-peer systems using Conflict-free Replicated Data Types (CRDTs) can offer a more privacy-friendly alternative to centralized solutions that are often used by Big Tech. However, traditional CRDTs assume that all replicas are trusted, which is not necessarily the case in a peer-to-peer system. This paper presents a protocol for secure state-based CRDTs which provide fine-grained confidentiality and integrity by using encryption per field in every (sub)-document. Our protocol guarantees Strong Eventual Consistency despite any Byzantine replicas. It provides a fine-grained, dynamic membership and key management system, without violating Strong Eventual Consistency or losing concurrent updates. Our evaluation shows that the protocol is suitable for use in interactive, collaborative applications.