Efficient Multi-branch Black-box Semantic-aware Targeted Attack Against Deep Hashing Retrieval

Deep hashing have achieved exceptional performance in retrieval tasks due to their robust representational capabilities. However, they inherit the vulnerability of deep neural networks to adversarial attacks. These models are susceptible to finely crafted adversarial perturbations that can lead them to return incorrect retrieval results. Although numerous adversarial attack methods have been proposed, there has been a scarcity of research focusing on targeted black-box attacks against deep hashing models. We introduce the Efficient Multi-branch Black-box Semantic-aware Targeted Attack against Deep Hashing Retrieval (EmbSTar), capable of executing targeted black-box attacks on hashing models. Initially, we distill the target model to create a knockoff model. Subsequently, we devised novel Target Fusion and Target Adaptation modules to integrate and enhance the semantic information of the target label and image. Knockoff model is then utilized to align the adversarial image more closely with the target image semantically. With the knockoff model, we can obtain powerful targeted attacks with few queries. Extensive experiments demonstrate that EmbSTar significantly surpasses previous models in its targeted attack capabilities, achieving SOTA performance for targeted black-box attacks.