Biometric Cryptosystem :: Technology, Encryption

As stated in ISO/IEC JTC1 SC37 biometrics is defined as the automated recognition of individuals based on their behavioural and biological characteristics. As discussed in section-------(Intro to biometrics) the main help involved in biometric recognition are Enrollment and Verification or Identification in general called as recognition. During the Enrollment process features of the captured biometric entity are converted to pathfinder, to be stored in database for further matching. At the stage of recognition , template obtained from the features of the realtime biometric entity are compared against the stored template. The result of matching process involved in recognition is either accept or reject1. It has been a long time belief that the biometric signals or data cannot be reconstructed from the stored templates and Cappelli et.al and Ross et.al23 has proven that the belief of biometric data reconstruction from the templates is possible. In order to protect the biometric data , several standard encryption algorithms has been used. But, this attempt leaves the biometric templates exposed during every trademark attempt4. Even homomorphic and asymmetric encryption schmes 567 represent some exceptions. Conventional cryptosystems is based on the possession of secret keys and key management is performed using second point authentication entity like password8. Decryption keys in this scheme could be obtained by using the password. To overcome the drawbacks of the existing schemes, biometric template protection schemes which are commonly called as biometric cryptosystems also referred to as Helper data-based scheme are proposed. Two major requirements of biometric information protection as per ISO/IEC FCD 24745 standard are,IrreversibilityReconstruction of original biometric template from the stored template should be made problematical whereas construction of protected biometric template from the stored template should be made easy.UnlinkabilitySeveral dif ferent versions of protected biometric templates can be generated based on the same biometric data, which is referred to as renewability whereas the protected templates should not cross-match, which is referred to as diversity.Biometric cryptosystems herein after referred to as BCS are designed to securely bind a digital key to a biometric or generate a digital key 9. BCS paves way for the growth of biometric dependant key-release and biometric template protection 1011. BCS is more difficult to forge, copy, share and distribute biometric data when compared to that of passwords 1. Conventional biometric cryptosystems perform fuzzy comparisons by applying decision thresholds. Decision thresholds are obtained based on the score distributions between actual and imposter subjects, whereas BCS gives only stable keys as output , which are required for matching at the authentication stage.