A Comprehensive Analysis on the Leakage of Fuzzy Matchers

The present paper presents a comprehensive analysis of potential information leakage in distance evaluation, with a specific emphasis on threshold-based obfuscated distance (i.e. Fuzzy Matcher). It includes detailed descriptions of various situations related to potential information leakage and specific attention is given to their consequences on security. Generic attacks corresponding to each scenario are outlined, and their complexities are assessed. The main contribution of this work lies in providing an upper bound on the security of a fuzzy matcher in scenarios where there is additional information leakage from the matcher, providing a straightforward understanding of the maximum level of achievable security and its potential implications for data privacy and security.