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Main Authors: Tansley, Edward, Makhlouf, Roy, Massart, Estelle, Cartis, Coralia
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.06519
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author Tansley, Edward
Makhlouf, Roy
Massart, Estelle
Cartis, Coralia
author_facet Tansley, Edward
Makhlouf, Roy
Massart, Estelle
Cartis, Coralia
contents Data reconstruction attacks on trained neural networks aim to recover the data on which the network has been trained and pose a significant threat to privacy, especially if the training dataset contains sensitive information. Here, we propose a unified optimization formulation of the data reconstruction problem based on initial and trained parameter values, incorporating state-of-the-art proposals. We show that in the random feature model, this formulation provably leads to training data reconstruction with high probability, provided the network width is sufficiently large; this unprecedented finite-width result uses PAC-style bounds. Furthermore, when the data lies in a low-dimensional subspace, we show that the network width requirement for successful reconstruction can be relaxed, with bounds depending on the subspace dimension rather than the ambient dimension. For general neural network models and unknown data orientations, we propose an efficient reconstruction algorithm that approximates the low-dimensional data subspace through the change in the first-layer weights during training and uses only the last-layer weights for reconstruction, thus reducing the search space dimension and the required network width for high-quality reconstructions. Our numerical experiments on synthetic datasets and CIFAR-10 confirm that our subspace-aware reconstruction approach outperforms standard full-space techniques.
format Preprint
id arxiv_https___arxiv_org_abs_2605_06519
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publishDate 2026
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spellingShingle Efficient Techniques for Data Reconstruction, with Finite-Width Recovery Guarantees
Tansley, Edward
Makhlouf, Roy
Massart, Estelle
Cartis, Coralia
Machine Learning
Data reconstruction attacks on trained neural networks aim to recover the data on which the network has been trained and pose a significant threat to privacy, especially if the training dataset contains sensitive information. Here, we propose a unified optimization formulation of the data reconstruction problem based on initial and trained parameter values, incorporating state-of-the-art proposals. We show that in the random feature model, this formulation provably leads to training data reconstruction with high probability, provided the network width is sufficiently large; this unprecedented finite-width result uses PAC-style bounds. Furthermore, when the data lies in a low-dimensional subspace, we show that the network width requirement for successful reconstruction can be relaxed, with bounds depending on the subspace dimension rather than the ambient dimension. For general neural network models and unknown data orientations, we propose an efficient reconstruction algorithm that approximates the low-dimensional data subspace through the change in the first-layer weights during training and uses only the last-layer weights for reconstruction, thus reducing the search space dimension and the required network width for high-quality reconstructions. Our numerical experiments on synthetic datasets and CIFAR-10 confirm that our subspace-aware reconstruction approach outperforms standard full-space techniques.
title Efficient Techniques for Data Reconstruction, with Finite-Width Recovery Guarantees
topic Machine Learning
url https://arxiv.org/abs/2605.06519