The importance of feature preprocessing for differentially private linear optimization

Fuente: arXiv
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Autori principali: Sun, Ziteng, Suresh, Ananda Theertha, Menon, Aditya Krishna
Natura: Preprint
Pubblicazione: 2023
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author Sun, Ziteng
Suresh, Ananda Theertha
Menon, Aditya Krishna
author_facet Sun, Ziteng
Suresh, Ananda Theertha
Menon, Aditya Krishna
contents Training machine learning models with differential privacy (DP) has received increasing interest in recent years. One of the most popular algorithms for training differentially private models is differentially private stochastic gradient descent (DPSGD) and its variants, where at each step gradients are clipped and combined with some noise. Given the increasing usage of DPSGD, we ask the question: is DPSGD alone sufficient to find a good minimizer for every dataset under privacy constraints? Towards answering this question, we show that even for the simple case of linear classification, unlike non-private optimization, (private) feature preprocessing is vital for differentially private optimization. In detail, we first show theoretically that there exists an example where without feature preprocessing, DPSGD incurs an optimality gap proportional to the maximum Euclidean norm of features over all samples. We then propose an algorithm called DPSGD-F, which combines DPSGD with feature preprocessing and prove that for classification tasks, it incurs an optimality gap proportional to the diameter of the features $\max_{x, x' \in D} \|x - x'\|_2$. We finally demonstrate the practicality of our algorithm on image classification benchmarks.
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id arxiv_https___arxiv_org_abs_2307_11106
institution arXiv
publishDate 2023
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spellingShingle The importance of feature preprocessing for differentially private linear optimization
Sun, Ziteng
Suresh, Ananda Theertha
Menon, Aditya Krishna
Machine Learning
Cryptography and Security
Information Theory
Training machine learning models with differential privacy (DP) has received increasing interest in recent years. One of the most popular algorithms for training differentially private models is differentially private stochastic gradient descent (DPSGD) and its variants, where at each step gradients are clipped and combined with some noise. Given the increasing usage of DPSGD, we ask the question: is DPSGD alone sufficient to find a good minimizer for every dataset under privacy constraints? Towards answering this question, we show that even for the simple case of linear classification, unlike non-private optimization, (private) feature preprocessing is vital for differentially private optimization. In detail, we first show theoretically that there exists an example where without feature preprocessing, DPSGD incurs an optimality gap proportional to the maximum Euclidean norm of features over all samples. We then propose an algorithm called DPSGD-F, which combines DPSGD with feature preprocessing and prove that for classification tasks, it incurs an optimality gap proportional to the diameter of the features $\max_{x, x' \in D} \|x - x'\|_2$. We finally demonstrate the practicality of our algorithm on image classification benchmarks.
title The importance of feature preprocessing for differentially private linear optimization
topic Machine Learning
Cryptography and Security
Information Theory
url https://arxiv.org/abs/2307.11106