Fake or tampered images pose a real problem in today’s life. It is easy to unknowingly be drawn to an interesting image that is false. Recently, with the emergence of generative adversarial networks (GANs), it becomes much more easy to generate high-quality fake images in a very realistic way. However, the current digital image forensics algorithms mainly focus on the detection of traditional tampered images or need prior knowledge of the network structure of GANs. Hence, verifying the authenticity of an image is very challenging. In this paper, we propose a general method for simultaneously detecting tampered images, and GANs generated images. First, we use the Scharr operator to extract the edge information of the image. Then, we converted the edge image information matrix into the gray level co-occurrence matrix (GLCM) to scale the image without loss of image information. Finally, GLCM was fed into the deep neural network designed based on depthwise separable convolution for training. Compared with other methods, our model achieves a higher macro average of F1 score of 0.9865. Meanwhile, our method has better performance in detecting tampered images and has strong generalization ability for many GANs models.

With the development of Internet technology, network security is under diverse threats. In particular, attackers can spread malicious uniform resource locators (URL) to carry out attacks such as phishing and spam. The research on malicious URL detection is significant for defending against these attacks. However, there are still some problems in the current research. For instance, malicious features cannot be extracted efficiently. Some existing detection methods are easy to evade by attackers. We design a malicious URL detection model based on a dynamic convolutional neural network (DCNN) to solve these problems. A new folding layer is added to the original multilayer convolution network. It replaces the pooling layer with the k-max-pooling layer. In the dynamic convolution algorithm, the width of feature mapping in the middle layer depends on the vector input dimension. Moreover, the pooling layer parameters are dynamically adjusted according to the length of the URL input and the depth of the current convolution layer, which is beneficial to extracting more in-depth features in a wider range. In this paper, we propose a new embedding method in which word embedding based on character embedding is leveraged to learn the vector representation of a URL. Meanwhile, we conduct two groups of comparative experiments. First, we conduct three contrast experiments, which adopt the same network structure and different embedding methods. The results prove that word embedding based on character embedding can achieve higher accuracy. We then conduct the other three experiences, which use the same embedding method proposed in this paper and use different network structures to determine which network is most suitable for our model. We verify that the model designed in this paper has the highest accuracy (98%) in detecting malicious URL through these experiences.

Using generative adversarial network (GAN) Goodfellow et al. (2014) for data enhancement of medical images is significantly helpful for many computer-aided diagnosis (CAD) tasks. A new GAN-based automated tampering attack, like CT-GAN Mirsky et al. (2019), has emerged. It can inject or remove lung cancer lesions to CT scans. Because the tampering region may even account for less than 1% of the original image, even state-of-the-art methods are challenging to detect the traces of such tampering. This paper proposes a two-stage cascade framework to detect GAN-based medical image small region forgery like CT-GAN. In the local detection stage, we train the detector network with small sub-images so that interference information in authentic regions will not affect the detector. We use depthwise separable convolution and residual networks to prevent the detector from over-fitting and enhance the ability to find forged regions through the attention mechanism. The detection results of all sub-images in the same image will be combined into a heatmap. In the global classification stage, using gray-level co-occurrence matrix (GLCM) can better extract features of the heatmap. Because the shape and size of the tampered region are uncertain, we use hyperplanes in an infinite-dimensional space for classification. Our method can classify whether a CT image has been tampered and locate the tampered position. Sufficient experiments show that our method can achieve excellent performance than the state-of-the-art detection methods.

Recent years have witnessed a boom of connected medical devices, which brings security issues in the meantime. Medical imaging devices, an essential part of medical cyber-physical systems, play a vital role in modern hospitals and are often life-critical. However, security and privacy issues in these medical cyber-physical systems are sometimes ignored. We perform an empirical study on imaging devices to analyse the security of medical cyber-physical systems. To be precise, we design a threat model and propose prospective attack techniques for medical imaging devices. To tackle potential cyber threats, we introduce protection mechanisms, evaluate the effectiveness and efficiency of protection mechanisms as well as its interplay with attack techniques. To scoring security, we design a hierarchical system that provides actionable suggestions for imaging devices in different scenarios. We investigate 15 devices from 9 manufacturers to demonstrate empirical comprehension and real-world security issues.

Deep learning, such as convolutional neural networks (CNNs), has been utilized in a number of cloud-based Internet of Things (IoT) applications. Security and privacy are two key considerations in any commercial deployment. Fully homomorphic encryption (FHE) is a popular privacy protection approach, and there have been attempts to integrate FHE with CNNs. However, a simple integration may lead to inefficiency in single-user services and fail to support many of the requirements in real-time applications. In this article, we propose a novel confused modulo projection-based FHE algorithm (CMP-FHE) that is designed to support floating-point operations. Then, we developed a parallelized runtime library based on CMP-FHE and compared it with the widely employed FHE library. Our results show that our library achieves faster speeds. Furthermore, we compared it with the state-of-the-art confused modulo projection-based library and the results demonstrated a speed improvement of 841.67 to 3056.25 times faster. Additionally, we construct a real-time homomorphic CNN (RT-HCNN) under the ciphertext-based framework using CMP-FHE, as well as using graphics processing units (GPUs) to facilitate acceleration. To demonstrate utility, we evaluate the proposed approach on the MNIST data set. Findings demonstrate that our proposed approach achieves a high accuracy rate of 99.13%. Using GPUs acceleration for ciphertext prediction results in us achieving a single prediction time of 79.5 ms. This represents the first homomorphic CNN capable of supporting real-time application and is approximately 58 times faster than Microsoft’s Lola scheme.