General Framework to Evaluate Unlinkability in Biometric Template Protection Systems
This addresses privacy concerns in biometric recognition by providing a standardized evaluation method for unlinkability, which is incremental as it builds on existing ISO/IEC standards and techniques.
The paper tackles the lack of systematic quantitative analysis for unlinkability in biometric template protection systems by proposing a new general framework, which is applied to assess four state-of-the-art techniques and shows advantages over existing metrics for block re-mapping.
The wide deployment of biometric recognition systems in the last two decades has raised privacy concerns regarding the storage and use of biometric data. As a consequence, the ISO/IEC 24745 international standard on biometric information protection has established two main requirements for protecting biometric templates: irreversibility and unlinkability. Numerous efforts have been directed to the development and analysis of irreversible templates. However, there is still no systematic quantitative manner to analyse the unlinkability of such templates. In this paper we address this shortcoming by proposing a new general framework for the evaluation of biometric templates' unlinkability. To illustrate the potential of the approach, it is applied to assess the unlinkability of four state-of-the-art techniques for biometric template protection: biometric salting, Bloom filters, Homomorphic Encryption and block re-mapping. For the last technique, the proposed framework is compared with other existing metrics to show its advantages.