Face embedding protection can use shared keys without losing security
Is it Possible to Generate Irreversible PolyProtected Templates from Face Embeddings using System-Specific Keys?
Cryptography and SecurityComputer Vision and Pattern Recognition
Summary
Usually, face data is protected by changing it uniquely for each person, making it hard to find duplicates across databases. This paper studies whether using the same protection key for everyone can still keep face data secure and irreversible. The authors show three ways to pick such shared keys that protect the data well. This means you can protect face data and still find if someone appears multiple times in a system.
What this means in practice
- •For identity management teams: Enable detection of duplicate face identities while keeping biometric data protected using shared system keys.
- •For security software developers: Build biometric authentication systems that use common protection keys without risking template reversibility.
Authors
Vedrana Krivokuća Hahn, Jérémy Maceiras, Sébastien Marcel
Abstract
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.