Making the Most of Parallel Composition in Differential Privacy

We show that the ‘optimal’ use of the parallel composition theorem corresponds to finding the size of the largest subset of queries that ‘overlap’ on the data domain, a quantity we call the maximum overlap of the queries. It has previously been shown that a certain instance of this problem, formulat...

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Autores principales: Smith Josh, Asghar Hassan Jameel, Gioiosa Gianpaolo, Mrabet Sirine, Gaspers Serge, Tyler Paul
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Lenguaje:EN
Publicado: Sciendo 2022
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spelling oai:doaj.org-article:2d316acc6e2445f09a898b07d3ad25d12021-12-05T14:11:10ZMaking the Most of Parallel Composition in Differential Privacy2299-098410.2478/popets-2022-0013https://doaj.org/article/2d316acc6e2445f09a898b07d3ad25d12022-01-01T00:00:00Zhttps://doi.org/10.2478/popets-2022-0013https://doaj.org/toc/2299-0984We show that the ‘optimal’ use of the parallel composition theorem corresponds to finding the size of the largest subset of queries that ‘overlap’ on the data domain, a quantity we call the maximum overlap of the queries. It has previously been shown that a certain instance of this problem, formulated in terms of determining the sensitivity of the queries, is NP-hard, but also that it is possible to use graph-theoretic algorithms, such as finding the maximum clique, to approximate query sensitivity. In this paper, we consider a significant generalization of the aforementioned instance which encompasses both a wider range of differentially private mechanisms and a broader class of queries. We show that for a particular class of predicate queries, determining if they are disjoint can be done in time polynomial in the number of attributes. For this class, we show that the maximum overlap problem remains NP-hard as a function of the number of queries. However, we show that efficient approximate solutions exist by relating maximum overlap to the clique and chromatic numbers of a certain graph determined by the queries. The link to chromatic number allows us to use more efficient approximate algorithms, which cannot be done for the clique number as it may underestimate the privacy budget. Our approach is defined in the general setting of f-differential privacy, which subsumes standard pure differential privacy and Gaussian differential privacy. We prove the parallel composition theorem for f-differential privacy. We evaluate our approach on synthetic and real-world data sets of queries. We show that the approach can scale to large domain sizes (up to 1020000), and that its application can reduce the noise added to query answers by up to 60%.Smith JoshAsghar Hassan JameelGioiosa GianpaoloMrabet SirineGaspers SergeTyler PaulSciendoarticledifferential privacyparallel compositiongraphsEthicsBJ1-1725Electronic computers. Computer scienceQA75.5-76.95ENProceedings on Privacy Enhancing Technologies, Vol 2022, Iss 1, Pp 253-273 (2022)
institution DOAJ
collection DOAJ
language EN
topic differential privacy
parallel composition
graphs
Ethics
BJ1-1725
Electronic computers. Computer science
QA75.5-76.95
spellingShingle differential privacy
parallel composition
graphs
Ethics
BJ1-1725
Electronic computers. Computer science
QA75.5-76.95
Smith Josh
Asghar Hassan Jameel
Gioiosa Gianpaolo
Mrabet Sirine
Gaspers Serge
Tyler Paul
Making the Most of Parallel Composition in Differential Privacy
description We show that the ‘optimal’ use of the parallel composition theorem corresponds to finding the size of the largest subset of queries that ‘overlap’ on the data domain, a quantity we call the maximum overlap of the queries. It has previously been shown that a certain instance of this problem, formulated in terms of determining the sensitivity of the queries, is NP-hard, but also that it is possible to use graph-theoretic algorithms, such as finding the maximum clique, to approximate query sensitivity. In this paper, we consider a significant generalization of the aforementioned instance which encompasses both a wider range of differentially private mechanisms and a broader class of queries. We show that for a particular class of predicate queries, determining if they are disjoint can be done in time polynomial in the number of attributes. For this class, we show that the maximum overlap problem remains NP-hard as a function of the number of queries. However, we show that efficient approximate solutions exist by relating maximum overlap to the clique and chromatic numbers of a certain graph determined by the queries. The link to chromatic number allows us to use more efficient approximate algorithms, which cannot be done for the clique number as it may underestimate the privacy budget. Our approach is defined in the general setting of f-differential privacy, which subsumes standard pure differential privacy and Gaussian differential privacy. We prove the parallel composition theorem for f-differential privacy. We evaluate our approach on synthetic and real-world data sets of queries. We show that the approach can scale to large domain sizes (up to 1020000), and that its application can reduce the noise added to query answers by up to 60%.
format article
author Smith Josh
Asghar Hassan Jameel
Gioiosa Gianpaolo
Mrabet Sirine
Gaspers Serge
Tyler Paul
author_facet Smith Josh
Asghar Hassan Jameel
Gioiosa Gianpaolo
Mrabet Sirine
Gaspers Serge
Tyler Paul
author_sort Smith Josh
title Making the Most of Parallel Composition in Differential Privacy
title_short Making the Most of Parallel Composition in Differential Privacy
title_full Making the Most of Parallel Composition in Differential Privacy
title_fullStr Making the Most of Parallel Composition in Differential Privacy
title_full_unstemmed Making the Most of Parallel Composition in Differential Privacy
title_sort making the most of parallel composition in differential privacy
publisher Sciendo
publishDate 2022
url https://doaj.org/article/2d316acc6e2445f09a898b07d3ad25d1
work_keys_str_mv AT smithjosh makingthemostofparallelcompositionindifferentialprivacy
AT asgharhassanjameel makingthemostofparallelcompositionindifferentialprivacy
AT gioiosagianpaolo makingthemostofparallelcompositionindifferentialprivacy
AT mrabetsirine makingthemostofparallelcompositionindifferentialprivacy
AT gaspersserge makingthemostofparallelcompositionindifferentialprivacy
AT tylerpaul makingthemostofparallelcompositionindifferentialprivacy
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