Unlinkable and irreversible biometric template protection based on bloom filters

Deployments of biometric technologies are already widely disseminated in numerous large-scale nation-wide projects. Since the protection of biometric reference data is of particular concern in order to safeguard individuals' privacy, biometric template protection schemes are designed to handle biometric reference data in an irreversible and unlinkable manner. In past years, schemes based on Bloom filters have been introduced and applied to various characteristics. However, thorough security analyses have exposed the original concept to be vulnerable to cross-matching attacks. In this article we present a general framework for the evaluation of unlinkability in biometric template protection schemes, as well as an improved, unlinkable and irreversible, system based on Bloom filters. In order to generate cross-matching resistant protected templates we re-design the original scheme and propose an additional, easily integrable, processing step, which is referred to as structure-preserving feature re-arrangement. The improved system is thoroughly evaluated on the publicly available face corpus of the BioSecure Multimodal Database. It is shown that the proposed scheme maintains the biometric performance of the unprotected system. Moreover, cross-matching resistance is achieved in the presence of existing attacks, considering adversary models where potential attackers are in possession of protected biometric templates as well as secret credentials. (C) 2016 Elsevier Inc. All rights reserved.