A generalized approach for cancellable template and its realization for Minutia Cylinder-Code

Hashing technology has gained much attention in protecting the biometric template lately. For instance, Index-of-Max (IoM), a recently reported hashing technique, is a ranking-based locality sensitive hashing technique, which illustrates the feasibility to protect the ordered and fixed-length biometric template. However, biometric templates are not always in the form of ordered and fixed-length. Rather, it may be an unordered and variable size point set, e.g., fingerprint minutiae, which restricts the usage of the traditional hashing technology. In this paper, we propose a generalized version of IoM hashing, namely gIoM, to enable the utilization of unordered and variable size biometric template. We demonstrate a realization by using a well-known variable size feature vector - fingerprint Minutia Cylinder-Code (MCC). The gIoM transforms MCC into index domain to form indexing-based feature representation. Consequently, the inversion of MCC from the transformed representation is computational infeasible, thus achieving non-invertibility while the performance is preserved. Public fingerprint databases FVC2002 and FVC2004 are employed for experiments. Furthermore, the security and privacy analysis suggest that gIoM meets the criteria of template protection, namely, non-invertibility, revocability, and non-linkability.