Beyond the Calibration Point: Mechanism Comparison in Differential Privacy

Fuente: arXiv
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Autori principali: Kaissis, Georgios, Kolek, Stefan, Balle, Borja, Hayes, Jamie, Rueckert, Daniel
Natura: Preprint
Pubblicazione: 2024
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author Kaissis, Georgios
Kolek, Stefan
Balle, Borja
Hayes, Jamie
Rueckert, Daniel
author_facet Kaissis, Georgios
Kolek, Stefan
Balle, Borja
Hayes, Jamie
Rueckert, Daniel
contents In differentially private (DP) machine learning, the privacy guarantees of DP mechanisms are often reported and compared on the basis of a single $(\varepsilon, δ)$-pair. This practice overlooks that DP guarantees can vary substantially even between mechanisms sharing a given $(\varepsilon, δ)$, and potentially introduces privacy vulnerabilities which can remain undetected. This motivates the need for robust, rigorous methods for comparing DP guarantees in such cases. Here, we introduce the $Δ$-divergence between mechanisms which quantifies the worst-case excess privacy vulnerability of choosing one mechanism over another in terms of $(\varepsilon, δ)$, $f$-DP and in terms of a newly presented Bayesian interpretation. Moreover, as a generalisation of the Blackwell theorem, it is endowed with strong decision-theoretic foundations. Through application examples, we show that our techniques can facilitate informed decision-making and reveal gaps in the current understanding of privacy risks, as current practices in DP-SGD often result in choosing mechanisms with high excess privacy vulnerabilities.
format Preprint
id arxiv_https___arxiv_org_abs_2406_08918
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Beyond the Calibration Point: Mechanism Comparison in Differential Privacy
Kaissis, Georgios
Kolek, Stefan
Balle, Borja
Hayes, Jamie
Rueckert, Daniel
Cryptography and Security
Artificial Intelligence
Machine Learning
Statistics Theory
In differentially private (DP) machine learning, the privacy guarantees of DP mechanisms are often reported and compared on the basis of a single $(\varepsilon, δ)$-pair. This practice overlooks that DP guarantees can vary substantially even between mechanisms sharing a given $(\varepsilon, δ)$, and potentially introduces privacy vulnerabilities which can remain undetected. This motivates the need for robust, rigorous methods for comparing DP guarantees in such cases. Here, we introduce the $Δ$-divergence between mechanisms which quantifies the worst-case excess privacy vulnerability of choosing one mechanism over another in terms of $(\varepsilon, δ)$, $f$-DP and in terms of a newly presented Bayesian interpretation. Moreover, as a generalisation of the Blackwell theorem, it is endowed with strong decision-theoretic foundations. Through application examples, we show that our techniques can facilitate informed decision-making and reveal gaps in the current understanding of privacy risks, as current practices in DP-SGD often result in choosing mechanisms with high excess privacy vulnerabilities.
title Beyond the Calibration Point: Mechanism Comparison in Differential Privacy
topic Cryptography and Security
Artificial Intelligence
Machine Learning
Statistics Theory
url https://arxiv.org/abs/2406.08918