Unified Privacy Guarantees for Decentralized Learning via Matrix Factorization

Fuente: arXiv
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Hauptverfasser: Bellet, Aurélien, Cyffers, Edwige, Frey, Davide, Gaudel, Romaric, Lerévérend, Dimitri, Taïani, François
Format: Preprint
Veröffentlicht: 2025
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author Bellet, Aurélien
Cyffers, Edwige
Frey, Davide
Gaudel, Romaric
Lerévérend, Dimitri
Taïani, François
author_facet Bellet, Aurélien
Cyffers, Edwige
Frey, Davide
Gaudel, Romaric
Lerévérend, Dimitri
Taïani, François
contents Decentralized Learning (DL) enables users to collaboratively train models without sharing raw data by iteratively averaging local updates with neighbors in a network graph. This setting is increasingly popular for its scalability and its ability to keep data local under user control. Strong privacy guarantees in DL are typically achieved through Differential Privacy (DP), with results showing that DL can even amplify privacy by disseminating noise across peer-to-peer communications. Yet in practice, the observed privacy-utility trade-off often appears worse than in centralized training, which may be due to limitations in current DP accounting methods for DL. In this paper, we show that recent advances in centralized DP accounting based on Matrix Factorization (MF) for analyzing temporal noise correlations can also be leveraged in DL. By generalizing existing MF results, we show how to cast both standard DL algorithms and common trust models into a unified formulation. This yields tighter privacy accounting for existing DP-DL algorithms and provides a principled way to develop new ones. To demonstrate the approach, we introduce MAFALDA-SGD, a gossip-based DL algorithm with user-level correlated noise that outperforms existing methods on synthetic and real-world graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2510_17480
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unified Privacy Guarantees for Decentralized Learning via Matrix Factorization
Bellet, Aurélien
Cyffers, Edwige
Frey, Davide
Gaudel, Romaric
Lerévérend, Dimitri
Taïani, François
Machine Learning
Decentralized Learning (DL) enables users to collaboratively train models without sharing raw data by iteratively averaging local updates with neighbors in a network graph. This setting is increasingly popular for its scalability and its ability to keep data local under user control. Strong privacy guarantees in DL are typically achieved through Differential Privacy (DP), with results showing that DL can even amplify privacy by disseminating noise across peer-to-peer communications. Yet in practice, the observed privacy-utility trade-off often appears worse than in centralized training, which may be due to limitations in current DP accounting methods for DL. In this paper, we show that recent advances in centralized DP accounting based on Matrix Factorization (MF) for analyzing temporal noise correlations can also be leveraged in DL. By generalizing existing MF results, we show how to cast both standard DL algorithms and common trust models into a unified formulation. This yields tighter privacy accounting for existing DP-DL algorithms and provides a principled way to develop new ones. To demonstrate the approach, we introduce MAFALDA-SGD, a gossip-based DL algorithm with user-level correlated noise that outperforms existing methods on synthetic and real-world graphs.
title Unified Privacy Guarantees for Decentralized Learning via Matrix Factorization
topic Machine Learning
url https://arxiv.org/abs/2510.17480