Your Diffusion Model is Secretly a Certifiably Robust Classifier

Fuente: arXiv
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Main Authors: Chen, Huanran, Dong, Yinpeng, Shao, Shitong, Hao, Zhongkai, Yang, Xiao, Su, Hang, Zhu, Jun
Format: Preprint
Published: 2024
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author Chen, Huanran
Dong, Yinpeng
Shao, Shitong
Hao, Zhongkai
Yang, Xiao
Su, Hang
Zhu, Jun
author_facet Chen, Huanran
Dong, Yinpeng
Shao, Shitong
Hao, Zhongkai
Yang, Xiao
Su, Hang
Zhu, Jun
contents Generative learning, recognized for its effective modeling of data distributions, offers inherent advantages in handling out-of-distribution instances, especially for enhancing robustness to adversarial attacks. Among these, diffusion classifiers, utilizing powerful diffusion models, have demonstrated superior empirical robustness. However, a comprehensive theoretical understanding of their robustness is still lacking, raising concerns about their vulnerability to stronger future attacks. In this study, we prove that diffusion classifiers possess $O(1)$ Lipschitzness, and establish their certified robustness, demonstrating their inherent resilience. To achieve non-constant Lipschitzness, thereby obtaining much tighter certified robustness, we generalize diffusion classifiers to classify Gaussian-corrupted data. This involves deriving the evidence lower bounds (ELBOs) for these distributions, approximating the likelihood using the ELBO, and calculating classification probabilities via Bayes' theorem. Experimental results show the superior certified robustness of these Noised Diffusion Classifiers (NDCs). Notably, we achieve over 80% and 70% certified robustness on CIFAR-10 under adversarial perturbations with \(\ell_2\) norms less than 0.25 and 0.5, respectively, using a single off-the-shelf diffusion model without any additional data.
format Preprint
id arxiv_https___arxiv_org_abs_2402_02316
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Your Diffusion Model is Secretly a Certifiably Robust Classifier
Chen, Huanran
Dong, Yinpeng
Shao, Shitong
Hao, Zhongkai
Yang, Xiao
Su, Hang
Zhu, Jun
Machine Learning
Computer Vision and Pattern Recognition
Generative learning, recognized for its effective modeling of data distributions, offers inherent advantages in handling out-of-distribution instances, especially for enhancing robustness to adversarial attacks. Among these, diffusion classifiers, utilizing powerful diffusion models, have demonstrated superior empirical robustness. However, a comprehensive theoretical understanding of their robustness is still lacking, raising concerns about their vulnerability to stronger future attacks. In this study, we prove that diffusion classifiers possess $O(1)$ Lipschitzness, and establish their certified robustness, demonstrating their inherent resilience. To achieve non-constant Lipschitzness, thereby obtaining much tighter certified robustness, we generalize diffusion classifiers to classify Gaussian-corrupted data. This involves deriving the evidence lower bounds (ELBOs) for these distributions, approximating the likelihood using the ELBO, and calculating classification probabilities via Bayes' theorem. Experimental results show the superior certified robustness of these Noised Diffusion Classifiers (NDCs). Notably, we achieve over 80% and 70% certified robustness on CIFAR-10 under adversarial perturbations with \(\ell_2\) norms less than 0.25 and 0.5, respectively, using a single off-the-shelf diffusion model without any additional data.
title Your Diffusion Model is Secretly a Certifiably Robust Classifier
topic Machine Learning
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2402.02316