Template security in biometric systems

In the last few years biometric technologies have been employed for automatic people authentication and identification at an increasing rate due to several inherent advantages they offer over conventional methods. However, increasing use of biometric technology raised many concerns and one of the biggest challenges to the wide applicability of biometric systems is the secure storage of biometric templates. More specifically, once some biometric data are compromised, they remain compromised forever and the privacy concerns arise from the fact that biometric data are tightly bound to a person's identity such that they can be used to violate their privacy.;In the first part of this defense, we will explain a recently proposed cryptographic primitive, called "secure sketch" in details and identify several practical issues that are not addressed in the existing theoretical framework. Later, we will introduce a general quantization-based secure sketch framework to design and analyze secure sketch for real world biometric templates. We further discuss randomized construction of secure sketches to provide cancelability and diversity and also discuss how to use secure sketch in the design of multi-factor authentication systems that allow easy revocation of user credentials. Experimental results that we obtained by testing our scheme using a face database will also be given.;In the second part, we will provide the details the "syndrome" approach which is basically an error correcting code (ECC)-based implementation of secure sketch framework. After discussing necessary requirements for having an efficient and secure implementation of syndrome approach for binary data, we will provide the details of a preprocessing approach that we proposed to transform the fingerprint data into binary strings having desirable properties for existing error-control codes. We also present experimental results that we obtained by testing our approach on a fingerprint database which prove the efficiency of our proposed transformation.