PhyCamo: A Robust Physical Camouflage via Contrastive Learning for Multi-View Physical Adversarial Attack

Deep neural networks (DNNs) have achieved remarkable success in widespread applications. Meanwhile, its vulnerability towards carefully crafted adversarial attacks captures special attention. Not only adversarial perturbations in digital space will fool the target DNNs-based detectors making a wrong decision, but also actually printed patches can be camouflaged to defeat detectors in physical space. In particular, multi-view physical adversarial attacks pose a more serious threat to practical scenarios. The existing attacks are still challenged in three aspects, i.e., high-cost data augmentation, attack performance gap between digital and physical space, and low attack transferability across DNNs. To overcome the challenges, we introduce PhyCamo, a robust physical camouflage framework based on contrastive learning that distinguishes itself from prior research in various critical ways: (1) data augmentation - it utilizes the diffusion model for data augmentation to efficiently simulate sophisticated physical dynamics in real-world; (2) robustness - it leverages contrastive learning to optimize physical camouflage against encoders with the state-of-the-art (SOTA) attack performance; (3) transferability - it mitigates the model-specific noise in the optimization by adopting diverse input methods, thereby amplifying the transferability between models. Extensive experiments are carried out on a car dataset, a tank dataset, and a pedestrian dataset, comparing with 6 classic multi-view physical adversarial attacks in both digital and physical spaces. The results demonstrate PhyCamo’s superior performance. For instance, it generates more effective physical camouflage (with higher attack success rate ×1.26 and reduce the model's average precision by 55%). PhyCamo can also help to improve the robustness of detectors through adversarial training, which contributes to the application of deep neural networks in the field of security sensitivity.