Security analysis of Bloom filter-based iris biometric template protection

This paper analyses the unlinkability and the irreversibility of the iris biometric template protection system based on Bloom filters introduced at ICB 2013. Hermans et al. presented at BIOSIG 2014 an attack on the unlinkability of these templates. In the worst case, their attack succeeds with probability at least 96%. But in their attack, they assume protected templates generated from the same iriscode. In this paper, we analyze unlinkability on protected templates generated with two different iriscodes coming from the same iris, and we moreover introduce irreversibility analysis that exploits non-uniformity of the data. Our experiments thus practically demonstrate new vulnerabilities of the scheme.