Throughout the ages all those who have been highly successful in great ventures and in the pursuit of great learning must have successfully undergone three stages:"Last night the west wind shriveled the green-clad trees; alone I climb the high tower, to gaze at the road stretching to the horizon" represents the first stage."I have no regrets as my girdle grows looser on my waist; with everlasting love I pine for you" represents the second stage."I have sought her in the crowd a hundred, a thousand times; suddenly turning back my head, I see her under the dimming lanterns" represents the third stage.
Erklärung zur DissertationHiermit versichere ich die vorliegende Dissertation selbständig nur mit den angegebenen Quellen und Hilfsmitteln angefertigt zu haben. Alle Stellen, die aus Quellen entnommen wurden, sind als solche kenntlich gemacht. Diese Arbeit hat in gleicher oder ähnlicher Form noch keiner Prüfungsbehörde vorgelegen.Darmstadt, den 4. August 2011 Xuebing Zhou
AbstractBiometrics enables convenient authentication based on a person's physical or behavioral characteristics. In comparison with knowledge-or token-based methods, it links an identity directly to its owner. Furthermore, it can not be forgotten or handed over easily. As biometric techniques have become more and more efficient and accurate, they are widely used in numerous areas. Among the most common application areas are physical and logical access controls, border control, authentication in banking applications and biometric identification in forensics.In this growing field of biometric applications, concerns about privacy and security cannot be neglected. The advantages of biometrics can revert to the opposite easily. The potential misuse of biometric information is not limited to the endangerment of user privacy, since biometric data potentially contain sensitive information like gender, race, state of health, etc. Different applications can be linked through unique biometric data. Additionally, identity theft is a severe threat to identity management, if revocation and reissuing of biometric references are practically impossible. Therefore, template protection techniques are developed to overcome these drawbacks and limitations of biometrics. Their advantage is the creation of multiple secure references from biometric data. These secure references are supposed to be unlinkable and non-invertible in order to achieve the desired level of security and to fulfill privacy requirements.The existing algorithms can be categorized into transformation-based approaches and biometric cryptosystems. The transformation-based approaches deploy different transformation or randomization functions, while the biometric cryptosystems construct secrets from biometric data. The integration in biometric systems is commonly accepted in research and their feasibility according to the recognition performance is proved. Despite of the success of biometric template protection techniques, their security and privacy properties are investigated only limitedly.This predomin...