FZFangzhen Zhao

Fangzhen Zhao

*This is an algorithmically generated author record based on publicly available information.

Current Organizations / Institutes

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Fangzhen Zhao has a total of 5 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Adversarial Detection from Derived Models

    by Fangzhen Zhao, Chenyi Zhang, Naipeng Dong, Ming Li

    Deep Neural Networks (DNNs) can be easily fooled by inputs that are crafted by adversaries. For example, an adversarial image can be forged by adding to an image a tiny perturbation which is often unnoticeable by human eyes, though the semantic interpretations of the original image and the adversarial image, which are represented as outputs of a DNN, may be drastically different. This weakness can potentially lead to serious consequences in security-critical applications such as medical diagnostic tests and self-driving vehicles. Most existing approaches for adversarial detection only have satisfactory performance for specific types of attacks. These methods do not generalize their performances when applied to a broad range of attacks, models or datasets. In this work, we propose a new adversarial detection method called Adversarial Detection from Derived Models (ADDM), which applies derived models to “simulate” the functionality of a DNN, and analyzes the distribution for the neuron activation values in the derived models as indicators for adversarial inputs. In order to further enhance performance, we propose a heuristic that selects neurons from the derived models that are sensitive to perturbations. We compare our approach with six existing adversarial detection approaches of different methodologies, and the experimental result confirms that the proposed approach has generally better performance regarding stability over different types of adversarial attacks on a variety of tested DNN models and datasets.

  • Open Access

    A Mask-Based Adversarial Defense Scheme

    by Weizhen Xu, Chenyi Zhang, Fangzhen Zhao, Liangda Fang

    Adversarial attacks hamper the functionality and accuracy of deep neural networks (DNNs) by meddling with subtle perturbations to their inputs. In this work, we propose a new mask-based adversarial defense scheme (MAD) for DNNs to mitigate the negative effect from adversarial attacks. Our method preprocesses multiple copies of a potential adversarial image by applying random masking, before the outputs of the DNN on all the randomly masked images are combined. As a result, the combined final output becomes more tolerant to minor perturbations on the original input. Compared with existing adversarial defense techniques, our method does not need any additional denoising structure or any change to a DNN’s architectural design. We have tested this approach on a collection of DNN models for a variety of datasets, and the experimental results confirm that the proposed method can effectively improve the defense abilities of the DNNs against all of the tested adversarial attack methods. In certain scenarios, the DNN models trained with MAD can improve classification accuracy by as much as 90% compared to the original models when given adversarial inputs.