ZeroPur: Succinct Training-Free Adversarial Purification

Fuente: arXiv
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Auteurs principaux: Liu, Erhu, Yang, Zonglin, Liu, Bo, Xiao, Bin, Bi, Xiuli
Format: Preprint
Publié: 2024
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author Liu, Erhu
Yang, Zonglin
Liu, Bo
Xiao, Bin
Bi, Xiuli
author_facet Liu, Erhu
Yang, Zonglin
Liu, Bo
Xiao, Bin
Bi, Xiuli
contents Adversarial purification is a kind of defense technique that can defend against various unseen adversarial attacks without modifying the victim classifier. Existing methods often depend on external generative models or cooperation between auxiliary functions and victim classifiers. However, retraining generative models, auxiliary functions, or victim classifiers relies on the domain of the fine-tuned dataset and is computation-consuming. In this work, we suppose that adversarial images are outliers of the natural image manifold, and the purification process can be considered as returning them to this manifold. Following this assumption, we present a simple adversarial purification method without further training to purify adversarial images, called ZeroPur. ZeroPur contains two steps: given an adversarial example, Guided Shift obtains the shifted embedding of the adversarial example by the guidance of its blurred counterparts; after that, Adaptive Projection constructs a directional vector by this shifted embedding to provide momentum, projecting adversarial images onto the manifold adaptively. ZeroPur is independent of external models and requires no retraining of victim classifiers or auxiliary functions, relying solely on victim classifiers themselves to achieve purification. Extensive experiments on three datasets (CIFAR-10, CIFAR-100, and ImageNet-1K) using various classifier architectures (ResNet, WideResNet) demonstrate that our method achieves state-of-the-art robust performance. The code will be publicly available.
format Preprint
id arxiv_https___arxiv_org_abs_2406_03143
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle ZeroPur: Succinct Training-Free Adversarial Purification
Liu, Erhu
Yang, Zonglin
Liu, Bo
Xiao, Bin
Bi, Xiuli
Computer Vision and Pattern Recognition
Cryptography and Security
Adversarial purification is a kind of defense technique that can defend against various unseen adversarial attacks without modifying the victim classifier. Existing methods often depend on external generative models or cooperation between auxiliary functions and victim classifiers. However, retraining generative models, auxiliary functions, or victim classifiers relies on the domain of the fine-tuned dataset and is computation-consuming. In this work, we suppose that adversarial images are outliers of the natural image manifold, and the purification process can be considered as returning them to this manifold. Following this assumption, we present a simple adversarial purification method without further training to purify adversarial images, called ZeroPur. ZeroPur contains two steps: given an adversarial example, Guided Shift obtains the shifted embedding of the adversarial example by the guidance of its blurred counterparts; after that, Adaptive Projection constructs a directional vector by this shifted embedding to provide momentum, projecting adversarial images onto the manifold adaptively. ZeroPur is independent of external models and requires no retraining of victim classifiers or auxiliary functions, relying solely on victim classifiers themselves to achieve purification. Extensive experiments on three datasets (CIFAR-10, CIFAR-100, and ImageNet-1K) using various classifier architectures (ResNet, WideResNet) demonstrate that our method achieves state-of-the-art robust performance. The code will be publicly available.
title ZeroPur: Succinct Training-Free Adversarial Purification
topic Computer Vision and Pattern Recognition
Cryptography and Security
url https://arxiv.org/abs/2406.03143