Shifted Interpolation for Differential Privacy

Fuente: arXiv
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Autori principali: Bok, Jinho, Su, Weijie, Altschuler, Jason M.
Natura: Preprint
Pubblicazione: 2024
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author Bok, Jinho
Su, Weijie
Altschuler, Jason M.
author_facet Bok, Jinho
Su, Weijie
Altschuler, Jason M.
contents Noisy gradient descent and its variants are the predominant algorithms for differentially private machine learning. It is a fundamental question to quantify their privacy leakage, yet tight characterizations remain open even in the foundational setting of convex losses. This paper improves over previous analyses by establishing (and refining) the "privacy amplification by iteration" phenomenon in the unifying framework of $f$-differential privacy--which tightly captures all aspects of the privacy loss and immediately implies tighter privacy accounting in other notions of differential privacy, e.g., $(\varepsilon,δ)$-DP and Rényi DP. Our key technical insight is the construction of shifted interpolated processes that unravel the popular shifted-divergences argument, enabling generalizations beyond divergence-based relaxations of DP. Notably, this leads to the first exact privacy analysis in the foundational setting of strongly convex optimization. Our techniques extend to many settings: convex/strongly convex, constrained/unconstrained, full/cyclic/stochastic batches, and all combinations thereof. As an immediate corollary, we recover the $f$-DP characterization of the exponential mechanism for strongly convex optimization in Gopi et al. (2022), and moreover extend this result to more general settings.
format Preprint
id arxiv_https___arxiv_org_abs_2403_00278
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Shifted Interpolation for Differential Privacy
Bok, Jinho
Su, Weijie
Altschuler, Jason M.
Machine Learning
Cryptography and Security
Optimization and Control
Statistics Theory
Noisy gradient descent and its variants are the predominant algorithms for differentially private machine learning. It is a fundamental question to quantify their privacy leakage, yet tight characterizations remain open even in the foundational setting of convex losses. This paper improves over previous analyses by establishing (and refining) the "privacy amplification by iteration" phenomenon in the unifying framework of $f$-differential privacy--which tightly captures all aspects of the privacy loss and immediately implies tighter privacy accounting in other notions of differential privacy, e.g., $(\varepsilon,δ)$-DP and Rényi DP. Our key technical insight is the construction of shifted interpolated processes that unravel the popular shifted-divergences argument, enabling generalizations beyond divergence-based relaxations of DP. Notably, this leads to the first exact privacy analysis in the foundational setting of strongly convex optimization. Our techniques extend to many settings: convex/strongly convex, constrained/unconstrained, full/cyclic/stochastic batches, and all combinations thereof. As an immediate corollary, we recover the $f$-DP characterization of the exponential mechanism for strongly convex optimization in Gopi et al. (2022), and moreover extend this result to more general settings.
title Shifted Interpolation for Differential Privacy
topic Machine Learning
Cryptography and Security
Optimization and Control
Statistics Theory
url https://arxiv.org/abs/2403.00278