GaitSpoofNet: advanced spatio-temporal architectures for vision-based presentation attack detection.

Introduction: Gait recognition offers a promising non-intrusive biometric modality, but its widespread adoption is critically hindered by its vulnerability to spoofing attacks, also known as Presentation Attacks (PAs). Developing effective gait anti-spoofing, or Presentation Attack Detection (PAD), mechanisms is therefore paramount for the security and reliability of gait-based authentication systems. While anti-spoofing research in gait has been addressed across both sensor-based (accelerometer/gyroscope) and vision-based (silhouette/image) modalities, this work specifically focuses on vision-based, image-level gait PAD, a domain that critically lacks dedicated deep temporal models and standardized benchmarks. Gait spoofing is defined as deliberate manipulation of a subject's external appearance to deceive the authentication system. Methods: Unlike prior work, we evaluate models under two practical scenarios: a public-access environment (random splitting) and a restricted-access scenario (LNSOCV). We present a comprehensive comparative study of advanced spatio-temporal architectures for gait anti-spoofing. By repurposing the CASIA-B dataset, we establish a standardized vision-based PAD baseline. We systematically evaluate models incorporating the official Mamba Selective State Space Model (mamba-ssm), a custom Inspired Mamba architecture, Gated Recurrent Units (GRU), and Long Short-Term Memory (LSTM) networks, all leveraging a robust CNN backbone. Results: Our extensive experiments demonstrate that all investigated advanced temporal models significantly improve gait spoofing detection over baseline methods. In open-access environments, the GRU-based model proved to be the most effective for anti-spoofing, reaching a state-of-the-art final validation accuracy of 0.9840 and an ROC-AUC of 0.9983. Discussion: Under restricted-access conditions, the LSTM-based model demonstrated the strongest overall performance.