Secure Multi-Party Homomorphic Encryption for Post-Quantum Biometric Recognition

This paper presents a post-quantum secure multi-party computation (MPC) scheme using homomorphic encryption (PQ-MHE) applied for fingerprint template protection. The proposed scheme leverages the CKKS cryptosystem for homomorphic operations and additive secret sharing (ASS) for splitting, storing, and comparing biometric templates across multiple servers. This architecture ensures that no single entity ever has access to the unencrypted templates. We benchmark the system using two-, three-, and four-server configurations. The scheme achieves a comparison time of 1.24 seconds and incurs 35 MB of communication, which can be reduced by approximately 98\% through caching and reusing the CKKS cryptographic context on the server side. The inherent approximate arithmetic of CKKS introduces a minor degradation, resulting in a 0.5 percentage point decrease in the true acceptance rate (TAR) compared to unencrypted fingerprint samples. The system is secure under a semi-honest adversary model with non-colluding servers and complies with the biometric information protection standards outlined in ISO/IEC 24745.