Recent studies demonstrated that deep neural networks (DNNs) are vulnerable to adversarial examples, which would seriously threaten security-sensitive applications. Existing works synthesized the adversarial examples by perturbing the original/benign images by leveraging the$\mathcal {L}_p$-norm to penalize the perturbations, which restricts the pixel-wise distance between the adversarial images and correspondingly benign images. However, they added perturbations globally to the benign images without explicitly considering their content/spacial structure, resulting in noticeable artifacts especially in those originally clean regions, e.g., sky and smooth surface. In this paper, we propose an invisible adversarial attack, which synthesizes adversarial examples that are visually indistinguishable from benign ones. We adaptively distribute the perturbation according to human sensitivity to a local stimulus in the benign image, i.e., the higher insensitivity, the more perturbation. Two types of adaptive adversarial attacks are proposed: 1) coarse-grained and 2) fine-grained. The former conducts$\mathcal {L}_p$-norm regularized by the novel spatial constraints, which utilizes the rich information of the cluttered regions to mask perturbation. The latter, called Just Noticeable Distortion (JND)-based adversarial attack, utilizes the proposed JND$_p$metric for better measuring the perceptual similarity, and adaptively sets penalty by weighting the pixel-wise perceptual redundancy of an image. We conduct extensive experiments on the MNIST, CIFAR-10 and ImageNet datasets and a comprehensive user study with 50 participants. The experimental results demonstrate that JND$_p$is a better metric for measuring the perceptual similarity than$\mathcal {L}_p$-norm, and the proposed adaptive adversarial attacks can synthesize indistinguishable adversarial examples from benign ones and outperform the state-of-the-art methods.

The massive photos shared through the social networks nowadays, e.g., Facebook and Instagram, have aided malicious entities to snoop private information, especially by utilizing deep neural networks (DNNs) to learn from those personal photos. To protect photo privacy against DNNs, recent advances adopting adversarial examples could successfully fool DNNs. However, they are sensitive to those image compression methods that are commonly used on social networks to reduce transmission bandwidth or storage space. A recent work proposed to resist JPEG compression, while the compression methods adopted in social networks are black boxes, and variation of compression methods would significantly degrade the resistance.

Person re-identification (re-ID) is the task of matching person images across camera views, which plays an important role in surveillance and security applications. Inspired by great progress of deep learning, deep re-ID models began to be popular and gained state-of-the-art performance. However, recent works found that deep neural networks (DNNs) are vulnerable to adversarial examples, posing potential threats to DNNs based applications. This phenomenon throws a serious question about whether deep re-ID based systems are vulnerable to adversarial attacks. In this paper, we take the first attempt to implement robust physical-world attacks against deep re-ID. We propose a novel attack algorithm, called advPattern, for generating adversarial patterns on clothes, which learns the variations of image pairs across cameras to pull closer the image features from the same camera, while pushing features from different cameras farther. By wearing our crafted “invisible cloak”, an adversary can evade person search, or impersonate a target person to fool deep re-ID models in physical world. We evaluate the effectiveness of our transformable patterns on adversaries' clothes with Market1501 and our established PRCS dataset. The experimental results show that the rank-1 accuracy of re-ID models for matching the adversary decreases from 87.9% to 27.1% under Evading Attack. Furthermore, the adversary can impersonate a target person with 47.1% rank-1 accuracy and 67.9% mAP under Impersonation Attack. The results demonstrate that deep re-ID systems are vulnerable to our physical attacks.