Local Differential Privacy with Correlated Noise Achieves Central-DP Optimal Cost

Fuente: arXiv
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Main Authors: Pathegama, Madhura, Avasarala, Srikanth, Cadambe, Viveck R., Ziani, Juba
Format: Preprint
Published: 2026
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author Pathegama, Madhura
Avasarala, Srikanth
Cadambe, Viveck R.
Ziani, Juba
author_facet Pathegama, Madhura
Avasarala, Srikanth
Cadambe, Viveck R.
Ziani, Juba
contents We study privately estimating the sum of $n$ user-held values in the presence of an honest-but-curious server. This motivates requiring privacy not only at data release but also throughout server-side computation. We therefore adopt the local (pure) differential privacy model, in which each user transmits a noise-perturbed value. It is well known that independent local noise typically incurs a substantial utility loss compared to the centralized model, where noise is added only after aggregation. We show that this gap is not fundamental. By carefully designing correlations among the locally added noise variables, we construct $\varepsilon$-DP mechanisms whose estimation cost matches the optimal cost achievable in the centralized setting, up to an arbitrarily small error.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30476
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Local Differential Privacy with Correlated Noise Achieves Central-DP Optimal Cost
Pathegama, Madhura
Avasarala, Srikanth
Cadambe, Viveck R.
Ziani, Juba
Information Theory
Cryptography and Security
Machine Learning
We study privately estimating the sum of $n$ user-held values in the presence of an honest-but-curious server. This motivates requiring privacy not only at data release but also throughout server-side computation. We therefore adopt the local (pure) differential privacy model, in which each user transmits a noise-perturbed value. It is well known that independent local noise typically incurs a substantial utility loss compared to the centralized model, where noise is added only after aggregation. We show that this gap is not fundamental. By carefully designing correlations among the locally added noise variables, we construct $\varepsilon$-DP mechanisms whose estimation cost matches the optimal cost achievable in the centralized setting, up to an arbitrarily small error.
title Local Differential Privacy with Correlated Noise Achieves Central-DP Optimal Cost
topic Information Theory
Cryptography and Security
Machine Learning
url https://arxiv.org/abs/2605.30476