Modern identity verification systems increasingly rely on facial images embedded in biometric documents such as electronic passports. To ensure global interoperability and security, these images must comply with strict standards defined by the International Civil Aviation Organization (ICAO), which specify acquisition, quality, and format requirements. However, once issued, these images may undergo unintentional degradations (e.g., compression, resizing) or malicious manipulations (e.g., morphing) and deceive facial recognition systems. In this study, we explore fragile watermarking, based on deep steganographic embedding as a proactive mechanism to certify the authenticity of ICAO-compliant facial images. By embedding a hidden image within the official photo at the time of issuance, we establish an integrity marker that becomes sensitive to any post-issuance modification. We assess how a range of image manipulations affects the recovered hidden image and show that degradation artifacts can serve as robust forensic cues. Furthermore, we propose a classification framework that analyzes the revealed content to detect and categorize the type of manipulation applied. Our experiments demonstrate high detection accuracy, including cross-method scenarios with multiple deep steganography-based models. These findings support the viability of fragile watermarking via steganographic embedding as a valuable tool for biometric document integrity verification.

翻译：现代身份验证系统日益依赖嵌入在电子护照等生物特征证件中的人脸图像。为确保全球互操作性与安全性，这些图像必须符合国际民用航空组织（ICAO）制定的严格标准，该标准明确了采集、质量与格式要求。然而，证件签发后，这些图像可能遭受无意劣化（如压缩、尺寸调整）或恶意篡改（如换脸攻击），从而欺骗人脸识别系统。本研究探索基于深度隐写嵌入的脆弱水印技术，将其作为主动机制用于认证符合ICAO标准的人脸图像的真实性。通过在签发时于官方照片内嵌入隐藏图像，我们建立了一种完整性标记，该标记对签发后的任何修改都具有敏感性。我们评估了各类图像操作对恢复隐藏图像的影响，并证明劣化伪影可作为鲁棒的取证线索。此外，我们提出一种分类框架，通过分析揭示的内容来检测并归类所施加的篡改类型。实验结果表明该方法具有高检测准确率，包括在采用多个基于深度隐写模型的跨方法场景中。这些发现证实了通过隐写嵌入实现脆弱水印作为生物特征证件完整性验证工具的有效性。