The Privacy Power of Correlated Noise in Decentralized Learning

Fuente: arXiv
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Main Authors: Allouah, Youssef, Koloskova, Anastasia, Firdoussi, Aymane El, Jaggi, Martin, Guerraoui, Rachid
Format: Preprint
Published: 2024
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author Allouah, Youssef
Koloskova, Anastasia
Firdoussi, Aymane El
Jaggi, Martin
Guerraoui, Rachid
author_facet Allouah, Youssef
Koloskova, Anastasia
Firdoussi, Aymane El
Jaggi, Martin
Guerraoui, Rachid
contents Decentralized learning is appealing as it enables the scalable usage of large amounts of distributed data and resources (without resorting to any central entity), while promoting privacy since every user minimizes the direct exposure of their data. Yet, without additional precautions, curious users can still leverage models obtained from their peers to violate privacy. In this paper, we propose Decor, a variant of decentralized SGD with differential privacy (DP) guarantees. Essentially, in Decor, users securely exchange randomness seeds in one communication round to generate pairwise-canceling correlated Gaussian noises, which are injected to protect local models at every communication round. We theoretically and empirically show that, for arbitrary connected graphs, Decor matches the central DP optimal privacy-utility trade-off. We do so under SecLDP, our new relaxation of local DP, which protects all user communications against an external eavesdropper and curious users, assuming that every pair of connected users shares a secret, i.e., an information hidden to all others. The main theoretical challenge is to control the accumulation of non-canceling correlated noise due to network sparsity. We also propose a companion SecLDP privacy accountant for public use.
format Preprint
id arxiv_https___arxiv_org_abs_2405_01031
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Privacy Power of Correlated Noise in Decentralized Learning
Allouah, Youssef
Koloskova, Anastasia
Firdoussi, Aymane El
Jaggi, Martin
Guerraoui, Rachid
Machine Learning
Cryptography and Security
Distributed, Parallel, and Cluster Computing
Optimization and Control
Decentralized learning is appealing as it enables the scalable usage of large amounts of distributed data and resources (without resorting to any central entity), while promoting privacy since every user minimizes the direct exposure of their data. Yet, without additional precautions, curious users can still leverage models obtained from their peers to violate privacy. In this paper, we propose Decor, a variant of decentralized SGD with differential privacy (DP) guarantees. Essentially, in Decor, users securely exchange randomness seeds in one communication round to generate pairwise-canceling correlated Gaussian noises, which are injected to protect local models at every communication round. We theoretically and empirically show that, for arbitrary connected graphs, Decor matches the central DP optimal privacy-utility trade-off. We do so under SecLDP, our new relaxation of local DP, which protects all user communications against an external eavesdropper and curious users, assuming that every pair of connected users shares a secret, i.e., an information hidden to all others. The main theoretical challenge is to control the accumulation of non-canceling correlated noise due to network sparsity. We also propose a companion SecLDP privacy accountant for public use.
title The Privacy Power of Correlated Noise in Decentralized Learning
topic Machine Learning
Cryptography and Security
Distributed, Parallel, and Cluster Computing
Optimization and Control
url https://arxiv.org/abs/2405.01031