Towards Trustworthy Federated Learning with Untrusted Participants

Fuente: arXiv
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Autori principali: Allouah, Youssef, Guerraoui, Rachid, Stephan, John
Natura: Preprint
Pubblicazione: 2025
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author Allouah, Youssef
Guerraoui, Rachid
Stephan, John
author_facet Allouah, Youssef
Guerraoui, Rachid
Stephan, John
contents Resilience against malicious participants and data privacy are essential for trustworthy federated learning, yet achieving both with good utility typically requires the strong assumption of a trusted central server. This paper shows that a significantly weaker assumption suffices: each pair of participants shares a randomness seed unknown to others. In a setting where malicious participants may collude with an untrusted server, we propose CafCor, an algorithm that integrates robust gradient aggregation with correlated noise injection, using shared randomness between participants. We prove that CafCor achieves strong privacy-utility trade-offs, significantly outperforming local differential privacy (DP) methods, which do not make any trust assumption, while approaching central DP utility, where the server is fully trusted. Empirical results on standard benchmarks validate CafCor's practicality, showing that privacy and robustness can coexist in distributed systems without sacrificing utility or trusting the server.
format Preprint
id arxiv_https___arxiv_org_abs_2505_01874
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Towards Trustworthy Federated Learning with Untrusted Participants
Allouah, Youssef
Guerraoui, Rachid
Stephan, John
Machine Learning
Cryptography and Security
Distributed, Parallel, and Cluster Computing
Resilience against malicious participants and data privacy are essential for trustworthy federated learning, yet achieving both with good utility typically requires the strong assumption of a trusted central server. This paper shows that a significantly weaker assumption suffices: each pair of participants shares a randomness seed unknown to others. In a setting where malicious participants may collude with an untrusted server, we propose CafCor, an algorithm that integrates robust gradient aggregation with correlated noise injection, using shared randomness between participants. We prove that CafCor achieves strong privacy-utility trade-offs, significantly outperforming local differential privacy (DP) methods, which do not make any trust assumption, while approaching central DP utility, where the server is fully trusted. Empirical results on standard benchmarks validate CafCor's practicality, showing that privacy and robustness can coexist in distributed systems without sacrificing utility or trusting the server.
title Towards Trustworthy Federated Learning with Untrusted Participants
topic Machine Learning
Cryptography and Security
Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2505.01874