Authors & Institutions
Gabrielle De Micheli
Advanced Security Team, LG Electronics, USA
Syed Mahbub Hafiz
Advanced Security Team, LG Electronics, USA
Geovandro Pereira
Advanced Security Team, LG Electronics, USA
Eduardo L. Cominetti
Advanced Security Team, LG Electronics, USA
Thales B. Paiva
Advanced Security Team, LG Electronics, USA
Universidade de São Paulo, São Paulo, Brazil
Jina Choi
Next-Generation Computing Research Lab, CTO Division, LG Electronics, South Korea
Marcos A. Simplicio Jr
Universidade de São Paulo, São Paulo, Brazil
Bahattin Yildiz
Advanced Security Team, LG Electronics, USA
What Problem It Solves
The paper tackles how to perform end-to-end encrypted face matching and identification without the huge memory and latency penalties that usually come with homomorphic search.
Key Result
The method reduces required rotation keys by about 91%, cuts client memory by roughly 14 GB, keeps server RAM below 10 GB for galleries up to 2^20 entries, and delivers GPU speedups of up to 17x over the CPU baseline. The authors report sub-second encrypted face recognition for galleries up to 2^15 entries.
Abstract
This paper studies encrypted similarity search for face recognition in client-server settings where embeddings are sensitive biometric data. It proposes a Baby-Step/Giant-Step diagonal algorithm and GPU-optimized CKKS kernels that cut memory overhead and speed up homomorphic matching enough to make private identification workflows more practical.
Research Starting Point
Enterprise face recognition increasingly runs as a client-server workflow where the client sends an embedding and the server performs gallery search. That architecture is operationally convenient but creates a serious privacy problem because face embeddings are persistent biometric identifiers. Prior fully homomorphic approaches showed the idea was possible, yet memory pressure and runtime still kept the design out of reach for many real deployments.
Method
The authors improve the earlier HyDia design with BSGS-Diagonal, which reuses precomputed rotations to evaluate consecutive matrix-vector products more efficiently and sharply reduces the rotation-key footprint. They then add GPU-aware similarity kernels on top of FIDESlib so ciphertext operations stay fused and avoid repeated CPU-GPU transfer overhead. Together, the algorithmic and systems changes move encrypted similarity search closer to something an infrastructure team could actually benchmark for production.
Paper Summary
The business value is straightforward: privacy-preserving face search is no longer only a compliance thought experiment. This paper shows that the infrastructure layer around secure biometric matching is becoming practical enough to matter in product and procurement conversations.