AI 中文总结
本研究证明使用系统特定密钥的PolyProtect可生成不可逆模板，实现身份去重，通过三种密钥选择方法验证安全性。
AI 中文摘要
本研究旨在回答一个问题：当PolyProtect生物特征模板保护方法应用于人脸嵌入时，使用系统特定密钥（即定义变换的相同C和E参数应用于所有对象的人脸嵌入），而非传统的对象特定密钥（即每个对象拥有自己的C和E参数），是否能够生成不可逆的保护模板。这对于确定我们是否可以在PolyProtected域中执行人脸身份去重至关重要，而在对象特定密钥场景中，由于与PolyProtect的不可关联性属性冲突（即，使用不同的C和E参数，可以为同一身份生成多个保护模板，而这些模板无法相互关联），这种去重是不可能的。我们通过实验（可使用我们的开源代码重现）证明，至少存在三种系统性地选择系统特定密钥的方法，能够产生不可逆的PolyProtected模板：（i）从预选的对象特定密钥中选取，（ii）将先前提出的密钥选择算法应用于随机向量，以及（iii）通过逼近一个“良好”的C/E对分布来构建系统特定密钥。我们的研究结果因此指向一个结论：确实可以在系统特定密钥场景中安全地操作PolyProtect，而不会降低模板保护潜力。这为在PolyProtected域中进行身份去重开辟了可能性。
英文摘要
This work aims to answer the question of whether it is possible to generate irreversible protected templates when the PolyProtect biometric template protection method is applied to face embeddings using system-specific keys (i.e., the same C and E parameters, which define the transform, are applied to all subjects' face embeddings), instead of the traditional subject-specific keys (i.e., each subject has their own C and E parameters). This is important for determining whether we can perform de-duplication of face identities in the PolyProtected domain, which is not possible in the subject-specific key scenario due to the clash with PolyProtect's unlinkability property (i.e., one could generate multiple protected templates belonging to the same identity, using different C and E parameters, such that those templates cannot be linked to each other). We present experiments (reproducible using our open-source code) to prove that there exist at least three ways of systematically selecting system-specific keys that produce irreversible PolyProtected templates: (i) from pre-selected subject-specific keys, (ii) by applying a previously proposed key selection algorithm to random vectors, and (iii) by approximating a "good" C/E pair distribution from which system-specific keys can be constructed. Our findings thus point to the conclusion that it is, indeed, possible to safely operate PolyProtect in the system-specific key scenario without degrading the template protection potential. This opens up the possibility for identity de-duplication in the PolyProtected domain.
CommentsSubmitted to TIFS journal on 12 May 2026 (under review). Consists of: 13 pages, 9 figures, 3 tables
