Training Set Reconstruction from Differentially Private Forests: How Effective is DP?

Fuente: arXiv
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Autores principales: Gorgé, Alice, Ferry, Julien, Gambs, Sébastien, Vidal, Thibaut
Formato: Preprint
Publicado: 2025
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author Gorgé, Alice
Ferry, Julien
Gambs, Sébastien
Vidal, Thibaut
author_facet Gorgé, Alice
Ferry, Julien
Gambs, Sébastien
Vidal, Thibaut
contents Recent research has shown that structured machine learning models such as tree ensembles are vulnerable to privacy attacks targeting their training data. To mitigate these risks, differential privacy (DP) has become a widely adopted countermeasure, as it offers rigorous privacy protection. In this paper, we introduce a reconstruction attack targeting state-of-the-art $ε$-DP random forests. By leveraging a constraint programming model that incorporates knowledge of the forest's structure and DP mechanism characteristics, our approach formally reconstructs the most likely dataset that could have produced a given forest. Through extensive computational experiments, we examine the interplay between model utility, privacy guarantees and reconstruction accuracy across various configurations. Our results reveal that random forests trained with meaningful DP guarantees can still leak portions of their training data. Specifically, while DP reduces the success of reconstruction attacks, the only forests fully robust to our attack exhibit predictive performance no better than a constant classifier. Building on these insights, we also provide practical recommendations for the construction of DP random forests that are more resilient to reconstruction attacks while maintaining a non-trivial predictive performance.
format Preprint
id arxiv_https___arxiv_org_abs_2502_05307
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Training Set Reconstruction from Differentially Private Forests: How Effective is DP?
Gorgé, Alice
Ferry, Julien
Gambs, Sébastien
Vidal, Thibaut
Machine Learning
Cryptography and Security
Recent research has shown that structured machine learning models such as tree ensembles are vulnerable to privacy attacks targeting their training data. To mitigate these risks, differential privacy (DP) has become a widely adopted countermeasure, as it offers rigorous privacy protection. In this paper, we introduce a reconstruction attack targeting state-of-the-art $ε$-DP random forests. By leveraging a constraint programming model that incorporates knowledge of the forest's structure and DP mechanism characteristics, our approach formally reconstructs the most likely dataset that could have produced a given forest. Through extensive computational experiments, we examine the interplay between model utility, privacy guarantees and reconstruction accuracy across various configurations. Our results reveal that random forests trained with meaningful DP guarantees can still leak portions of their training data. Specifically, while DP reduces the success of reconstruction attacks, the only forests fully robust to our attack exhibit predictive performance no better than a constant classifier. Building on these insights, we also provide practical recommendations for the construction of DP random forests that are more resilient to reconstruction attacks while maintaining a non-trivial predictive performance.
title Training Set Reconstruction from Differentially Private Forests: How Effective is DP?
topic Machine Learning
Cryptography and Security
url https://arxiv.org/abs/2502.05307