Security analysis and improvement of some biometric protected templates based on Bloom filters

In this work, we develop an unlinkability and irreversibility analysis of the so-called Bloom filter-based iris biometric template protection introduced at ICB 2013. We go further than the unlinkability analysis of Hermans et al. presented at BIOSIG 2014. Firstly we analyse unlinkability on protected templates built from two different iriscodes coming from the same iris whereas Hermans et al. analysed only protected templates from the same iriscode. Moreover we introduce an irreversibility analysis that exploits non-uniformity of the biometric data. Our experiments demonstrate new vulnerabilities of this scheme. Then we will discuss the security of other similar protected biometric templates based on Blooms filters that have been suggested in the literature since 2013. Finally we suggest a Secure Multiparty Computation (SMC) protocol, that benefits of the alignment-free feature of this Bloom filter construction, in order to compute efficiently and securely the matching scores.