Proactive DP: A Multple Target Optimization Framework for DP-SGD

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Main Authors: van Dijk, Marten, Nguyen, Nhuong V., Nguyen, Toan N., Nguyen, Lam M., Nguyen, Phuong Ha
Format: Preprint
Published: 2021
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author van Dijk, Marten
Nguyen, Nhuong V.
Nguyen, Toan N.
Nguyen, Lam M.
Nguyen, Phuong Ha
author_facet van Dijk, Marten
Nguyen, Nhuong V.
Nguyen, Toan N.
Nguyen, Lam M.
Nguyen, Phuong Ha
contents We introduce a multiple target optimization framework for DP-SGD referred to as pro-active DP. In contrast to traditional DP accountants, which are used to track the expenditure of privacy budgets, the pro-active DP scheme allows one to a-priori select parameters of DP-SGD based on a fixed privacy budget (in terms of $ε$ and $δ$) in such a way to optimize the anticipated utility (test accuracy) the most. To achieve this objective, we first propose significant improvements to the moment account method, presenting a closed-form $(ε,δ)$-DP guarantee that connects all parameters in the DP-SGD setup. We show that DP-SGD is $(ε<0.5,δ=1/N)$-DP if $σ=\sqrt{2(ε+\ln(1/δ))/ε}$ with $T$ at least $\approx 2k^2/ε$ and $(2/e)^2k^2-1/2\geq \ln(N)$, where $T$ is the total number of rounds, and $K=kN$ is the total number of gradient computations where $k$ measures $K$ in number of epochs of size $N$ of the local data set. We prove that our expression is close to tight in that if $T$ is more than a constant factor $\approx 4$ smaller than the lower bound $\approx 2k^2/ε$, then the $(ε,δ)$-DP guarantee is violated. The above DP guarantee can be enhanced in thatDP-SGD is $(ε, δ)$-DP if $σ= \sqrt{2(ε+\ln(1/δ))/ε}$ with $T$ at least $\approx 2k^2/ε$ together with two additional, less intuitive, conditions that allow larger $ε\geq 0.5$. Our DP theory allows us to create a utility graph and DP calculator. These tools link privacy and utility objectives and search for optimal experiment setups, efficiently taking into account both accuracy and privacy objectives, as well as implementation goals. We furnish a comprehensive implementation flow of our proactive DP, with rigorous experiments to showcase the proof-of-concept.
format Preprint
id arxiv_https___arxiv_org_abs_2102_09030
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Proactive DP: A Multple Target Optimization Framework for DP-SGD
van Dijk, Marten
Nguyen, Nhuong V.
Nguyen, Toan N.
Nguyen, Lam M.
Nguyen, Phuong Ha
Machine Learning
Optimization and Control
We introduce a multiple target optimization framework for DP-SGD referred to as pro-active DP. In contrast to traditional DP accountants, which are used to track the expenditure of privacy budgets, the pro-active DP scheme allows one to a-priori select parameters of DP-SGD based on a fixed privacy budget (in terms of $ε$ and $δ$) in such a way to optimize the anticipated utility (test accuracy) the most. To achieve this objective, we first propose significant improvements to the moment account method, presenting a closed-form $(ε,δ)$-DP guarantee that connects all parameters in the DP-SGD setup. We show that DP-SGD is $(ε<0.5,δ=1/N)$-DP if $σ=\sqrt{2(ε+\ln(1/δ))/ε}$ with $T$ at least $\approx 2k^2/ε$ and $(2/e)^2k^2-1/2\geq \ln(N)$, where $T$ is the total number of rounds, and $K=kN$ is the total number of gradient computations where $k$ measures $K$ in number of epochs of size $N$ of the local data set. We prove that our expression is close to tight in that if $T$ is more than a constant factor $\approx 4$ smaller than the lower bound $\approx 2k^2/ε$, then the $(ε,δ)$-DP guarantee is violated. The above DP guarantee can be enhanced in thatDP-SGD is $(ε, δ)$-DP if $σ= \sqrt{2(ε+\ln(1/δ))/ε}$ with $T$ at least $\approx 2k^2/ε$ together with two additional, less intuitive, conditions that allow larger $ε\geq 0.5$. Our DP theory allows us to create a utility graph and DP calculator. These tools link privacy and utility objectives and search for optimal experiment setups, efficiently taking into account both accuracy and privacy objectives, as well as implementation goals. We furnish a comprehensive implementation flow of our proactive DP, with rigorous experiments to showcase the proof-of-concept.
title Proactive DP: A Multple Target Optimization Framework for DP-SGD
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2102.09030