An Analysis of Random Projections in Cancelable Biometrics
This work addresses the trade-off between security and performance in biometric authentication systems, providing a theoretical foundation for an incremental improvement in cancelable biometrics.
The paper analyzes why random projections are essential in cancelable biometrics by showing they preserve the subspace structure of data vectors, with theoretical bounds on the required number of vectors and empirical validation on face recognition datasets.
With increasing concerns about security, the need for highly secure physical biometrics-based authentication systems utilizing \emph{cancelable biometric} technologies is on the rise. Because the problem of cancelable template generation deals with the trade-off between template security and matching performance, many state-of-the-art algorithms successful in generating high quality cancelable biometrics all have random projection as one of their early processing steps. This paper therefore presents a formal analysis of why random projections is an essential step in cancelable biometrics. By formally defining the notion of an \textit{Independent Subspace Structure} for datasets, it can be shown that random projection preserves the subspace structure of data vectors generated from a union of independent linear subspaces. The bound on the minimum number of random vectors required for this to hold is also derived and is shown to depend logarithmically on the number of data samples, not only in independent subspaces but in disjoint subspace settings as well. The theoretical analysis presented is supported in detail with empirical results on real-world face recognition datasets.