  Adversarial examples are intentionally crafted data with the purpose of
deceiving neural networks into misclassification. When we talk about strategies
to create such examples, we usually refer to perturbation-based methods that
fabricate adversarial examples by applying invisible perturbations onto normal
data. The resulting data reserve their visual appearance to human observers,
yet can be totally unrecognizable to DNN models, which in turn leads to
completely misleading predictions. In this paper, however, we consider crafting
adversarial examples from existing data as a limitation to example diversity.
We propose a non-perturbation-based framework that generates native adversarial
examples from class-conditional generative adversarial networks.As such, the
generated data will not resemble any existing data and thus expand example
diversity, raising the difficulty in adversarial defense. We then extend this
framework to pre-trained conditional GANs, in which we turn an existing
generator into an "adversarial-example generator". We conduct experiments on
our approach for MNIST and CIFAR10 datasets and have satisfactory results,
showing that this approach can be a potential alternative to previous attack
strategies.
