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Recent advancements in person recognition have raised concerns about identity privacy leaks. Gait recognition through millimeter-wave radar provides a privacy-centric method. However, it is challenged by lower accuracy due to the sparse data these sensors capture. We are the first to investigate a cross-modal method, IdentityKD, to enhance gait-based person recognition with the assistance of facial data. IdentityKD involves a training process using both gait and facial data, while the inference stage is conducted exclusively with gait data. To effectively transfer facial knowledge to the gait model, we create a composite feature representation using contrastive learning. This method integrates facial and gait features into a unified embedding that captures the unique identityspecific information from both modalities. We employ two distinct contrastive learning losses. One minimizes the distance between embeddings of data pairs from the same person, enhancing intraclass compactness, while the other maximizes the distance between embeddings of data pairs from different individuals, improving inter-class separability. Additionally, we use an identity-wise distillation strategy, which tailors the training process for each individual, ensuring that the model learns to distinguish between different identities more effectively. Our experiments on a dataset of 36 subjects, each providing over 5000 face-gait pairs, demonstrate that IdentityKD improves identity recognition accuracy by 6.5% compared to baseline methods. 

Voice-controlled interfaces are essential in modern smart devices, but they remain vulnerable to replay attacks that compromise voice authentication systems. Existing voice liveness detection methods often struggle to distinguish human speech from replayed audio. This paper introduces a novel approach, LiveGuard, utilizing wavelet scattering transform (WST) and Mel spectrogram scaling with a lightweight ResNet architecture to enhance voice liveness detection. WST captures robust hierarchical features, while Mel spectrogram scaling extracts fine-grained acoustic details, which the lightweight ResNet efficiently processes to identify live voice. Experimental results demonstrate accuracy improvements of 6% with WST and Mel spectrogram scaling, achieving a top accuracy of 97.17% on POCO dataset. Meanwhile, LiveGuard demonstrates superior performance on ASVspoof2019 and ASVspoof2021 benchmarks. It achieves the lowest equal error rate (EER) of 0.13%, and a min t-DCF of 0.00126 on ASVspoof2019, and an EER of 0.42% on ASVspoof2021, surpassing state-of-the-art methods.