Krum Federated Chain (KFC): Using blockchain to defend against adversarial attacks in Federated Learning
Mario García-Márquez, Nuria Rodríguez-Barroso, M. Victoria Luzón, Francisco Herrera
TL;DR
The paper tackles the vulnerability of Federated Learning to adversarial attacks by integrating blockchain with FL. It first evaluates Proof of Federated Learning (PoFL) as a defense, finding it effective when at least one miner remains honest, but vulnerable if all miners are compromised. To strengthen security, it introduces Krum Federated Chain (KFC), which combines PoFL with the Krum aggregation to defend against arbitrary attack configurations, including all-miner attacks. Across EMNIST, Fashion-MNIST, and CIFAR-10, PoFL and KFC prove energy-efficient and scalable, with KFC delivering robust performance under both Byzantine and backdoor threats, outperforming several baselines. The work highlights the potential of blockchain-based defenses for resilient FL and outlines future work toward broader attack classes and privacy-aware designs.
Abstract
Federated Learning presents a nascent approach to machine learning, enabling collaborative model training across decentralized devices while safeguarding data privacy. However, its distributed nature renders it susceptible to adversarial attacks. Integrating blockchain technology with Federated Learning offers a promising avenue to enhance security and integrity. In this paper, we tackle the potential of blockchain in defending Federated Learning against adversarial attacks. First, we test Proof of Federated Learning, a well known consensus mechanism designed ad-hoc to federated contexts, as a defense mechanism demonstrating its efficacy against Byzantine and backdoor attacks when at least one miner remains uncompromised. Second, we propose Krum Federated Chain, a novel defense strategy combining Krum and Proof of Federated Learning, valid to defend against any configuration of Byzantine or backdoor attacks, even when all miners are compromised. Our experiments conducted on image classification datasets validate the effectiveness of our proposed approaches.
