Over the recent years, multimodal named entity recognition has gained increasing attentions due to its wide applications in social media. The key factor of multimodal named entity recognition is to effectively fuse information of different modalities. Existing works mainly focus on reinforcing textual representations by fusing image features via the cross-modal attention mechanism. However, these works are limited in reinforcing the text modality at the token level. As a named entity usually contains several tokens, modeling token-level inter-modal interactions is suboptimal for the multimodal named entity recognition problem. In this work, we propose a multimodal named entity recognition approach dubbed Adaptive Multi-scale Language Reinforcement (AMLR) to implement entity-level language reinforcement. To this end, our model first expands token-level textual representations into multi-scale textual representations which are composed of language units of different lengths. After that, the visual information reinforces the language modality by modeling the cross-modal attention between images and expanded multi-scale textual representations. Unlike existing token-level language reinforcement methods, the word sequences of named entities can be directly interacted with the visual features as a whole, making the modeled cross-modal correlations more reasonable. Although the underlying entity is not given, the training procedure can encourage the relevant image contents to adaptively attend to the appropriate language units, making our approach not rely on the pipeline design. Comprehensive evaluation results on two public Twitter datasets clearly demonstrate the superiority of our proposed model.

Malware detection and classification are crucial for protecting digital devices and information systems. Accurate identification of malware enables researchers and incident responders to take prompt measures against malware and mitigate its damage. With the development of attention mechanisms in the field of computer vision, attention mechanism-based malware detection techniques are also rapidly evolving. The essence of the attention mechanism is to focus on the information of interest and suppress the useless information. In this paper, we develop different plug-and-play attention mechanisms based on the ResNeXt tagging model, where the designed model is trained to focus on the malware features by capturing the malware image channel perception field of view and is also able to provide more helpful and flexible information than other methods. We have named this designed neural network ResNeXt+, and its core modules are built with different plug-and-play attention mechanisms. Extensive experimental results show that ResNeXt+ is effective and efficient in malware detection and classification with high classification accuracy. The proposed methods outperform the state-of-the-art techniques with seven benchmark datasets. Cross-dataset experiments conducted on the Windows and Android datasets, with an accuracy of 90.64% on cross-dataset detection of the android. Ablation experiments are also conducted on seven datasets, which demonstrate that attention mechanisms can improve malware detection and classification accuracy.

Steganography is a technique that hides secret messages into a public multimedia object without raising suspicion from third parties. However, most existing works cannot provide good robustness against lossy JPEG compression while maintaining a relatively large embedding capacity. This paper presents an end-to-end robust steganography system based on the invertible neural network (INN). Instead of hiding in the spatial domain, our method directly hides secret messages into the discrete cosine transform (DCT) coefficients of the cover image, which significantly improves the robustness and anti-steganalysis security. A mutual information loss is first proposed to constrain the flow of information in INN. Besides, a two-way fusion module (TWFM) is implemented, utilizing spatial and DCT domain features as auxiliary information to facilitate message extraction. These two designs aid in recovering secret messages from the DCT coefficients losslessly. Experimental results demonstrate that our method yields significantly lower error rates than other existing hiding methods. For example, our method achieves reliable extraction with 0 error rate for 1 bit per pixel (bpp) embedding payload; and under the JPEG compression with quality factor QF=10, the error rate of our method is about 22% lower than the state-of-the-art robust image hiding methods, which demonstrates remarkable robustness against JPEG compression.

Speech anti-spoofing models protect media from malicious fake speech but are vulnerable to adversarial attacks. Studies of adversarial attacks are conducive to developing robust speech anti-spoofing systems. Existing transfer-based attack methods mainly craft adversarial speech examples at the handcrafted-feature level, which have limited attack ability against the real-world anti-spoofing systems, as these systems only have raw waveform input interfaces. In this work, we propose a waveform-level input data transformation, called the temporal smoothing method, to generate more transferable adversarial speech examples. In the optimization iterations of the adversarial perturbation, we randomly smooth input waveforms to prevent the adversarial examples from overfitting white-box surrogate models. The proposed transformation can be combined with any iterative gradient-based attack method. Extensive experiments demonstrate that our method significantly enhances the transferability of waveform-level adversarial speech examples.

Supraliminal channels were introduced in 1998 as a means to achieve public key exchange in the presence of an active warden. These channels have content visible to all principals-their content is not concealed or protected by a secret key-but are highly robust to an active warden. It is assumed that this high robustness allows the transmission of key exchange datagrams. In this paper, we provide a theoretical model for supraliminal channels as channels of random data with a constraint on their distribution. We present a surprising result that in such a model, vanishingly small tampering can indefinitely derail key exchange. Unlike traditional communication theory, the specific constraints of steganographic channels prevent the use of redundancy to achieve more reliable transmission, and can even make communication more fragile to an active adversary. This result requires a vigilant adversary, however, and we propose a protocol to increase the probability of successful key exchange in the event of a pause in the warden's tampering.