Inference-Based Similarity Search in Randomized Montgomery Domains for Privacy-Preserving Biometric Identification
This addresses the vulnerability of biometric systems to adversarial attacks by improving search efficiency and scalability for privacy protection, though it is an incremental advancement over existing secure methods.
The paper tackles the problem of efficient and scalable privacy-preserving similarity search in biometric identification by proposing an inference-based framework that conceals Hamming distances in dynamic intervals, achieving search accuracy close to secure computation methods while reducing costs by orders of magnitude.
Similarity search is essential to many important applications and often involves searching at scale on high-dimensional data based on their similarity to a query. In biometric applications, recent vulnerability studies have shown that adversarial machine learning can compromise biometric recognition systems by exploiting the biometric similarity information. Existing methods for biometric privacy protection are in general based on pairwise matching of secured biometric templates and have inherent limitations in search efficiency and scalability. In this paper, we propose an inference-based framework for privacy-preserving similarity search in Hamming space. Our approach builds on an obfuscated distance measure that can conceal Hamming distance in a dynamic interval. Such a mechanism enables us to systematically design statistically reliable methods for retrieving most likely candidates without knowing the exact distance values. We further propose to apply Montgomery multiplication for generating search indexes that can withstand adversarial similarity analysis, and show that information leakage in randomized Montgomery domains can be made negligibly small. Our experiments on public biometric datasets demonstrate that the inference-based approach can achieve a search accuracy close to the best performance possible with secure computation methods, but the associated cost is reduced by orders of magnitude compared to cryptographic primitives.