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Biometric Security. Pieter.Hartel@utwente.nl. Problem. People use weak passwords People write the pin code on their bank card Biometrics cannot be “forgotten” and you do not have to “think of it”. Personal Identification. Associating an individual with an identity: Something you have
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Biometric Security Pieter.Hartel@utwente.nl
Problem • People use weak passwords • People write the pin code on their bank card • Biometrics cannot be “forgotten” and you do not have to “think of it” IIS
Personal Identification Associating an individual with an identity: • Something you have • Token, smart card • Something you know • Password, pin • Something you are: • Physiological • Behavioural IIS
Forms of Identification • Authentication (aka Verification) • Am I who a claim to be? • Recognition (aka Identification) • Who am I? • Harder than Authentication (why?) IIS
Physiological or Behavioural? [Jai00] A. K. Jain, L. Hong, and S. Pankanti. Biometric identification. Commun. ACM, 43(2):90-98, Feb 2000. http://doi.acm.org/10.1145/328236.328110 IIS
Verification Verification is easier than identification… IIS
Two examples • Hand geometry • Fingerprint IIS
FBI classification • What is your right hand index finger? Arch Whorl Loop Accidental IIS
Fingerprint matching • Ridge thinning & extraction • Minutiae (bifurcation, end point) detection • Ridge based alignment & overlaying IIS
Desired Characteristics • Biometric • Universal • Unique • Permanent • Collectable • System • Performance • Acceptability • Circumvention Watch this video [Put00] T. van der Putte and J. Keuning. Biometrical fingerprint recognition: Don't get your fingers burned. In 4th Int. IFIP wg 8.8 Conf. Smart card research and advanced application (CARDIS), pages 289-303, Bristol, UK, Sep 2000. Kluwer Academic Publishers, Boston, Massachusetts. http://www.keuning.com/biometry/Biometrical_Fingerprint_Recognition.pdf IIS
Some Comparisons IIS
Biometrics is not perfect • High False Accept rate is bad for high security applications -- dangerous • High False Reject rate is bad for high usability applications -- annoying IIS
Receiver Operating Characteristics Low False Accept Rate High Low False Reject Rate High IIS
Attacks • How many templates do you have? IIS
Template protection • Requirements • Diversity (no cross matching of data bases for privacy) • Revocability (easy to replace template) • Security (hard to obtain the original) • Performance (matching must be robust) • Why does encryption not work? • Two examples • Non-invertible transforms • Fuzzy commitment [Jai08] A. K. Jain, K. Nandakumar, and A. Nagar. Biometric template security. EURASIP Journal on Advances in Signal Processing, 2008:579416, 2008. http://dx.doi.org/10.1155/2008/579416 IIS
Non invertible transform “crumple” • User specific transformation (revocability) • Locally smooth translation outside mather tolerance (performance) • Globally non smooth (security) [Rat06] N. Ratha, J. Connell, R. M. Bolle, and S. Chikkerur. Cancelable biometrics: A case study in fingerprints. In 18th Int. Conf. on Pattern Recognition (ICPR), volume 4, pages 370-373, Honkong, China, Aug 2006. IEEE Computer Society. http://dx.doi.org/10.1109/ICPR.2006.353 IIS
Fuzzy commitment Example • Idea • Use biometric template : x • As a corrupted code word : c = x-δ • The commitment is • Hash code word for security : h(c) • Leave distance in clear for fuzziness : δ • Verification • Measure : x’ • Compute: c’ = decode (x’- δ) • Match if h(c’) = h(c) x x’ δ δ 100 200 300 c c’? c’? 100 200 [Jue99a] A. Juels and M. Wattenberg. A fuzzy commitment scheme. In 6th ACM conf. on Computer and communications security (CCS), pages 28-36, Kent Ridge Digital Labs, Singapore, 1999. ACM. http://doi.acm.org/10.1145/319709.319714 IIS
Template protection application [Buh07] I. R. Buhan, J. M. Doumen, P. H. Hartel, and R. N. J. Veldhuis. Secure ad-hoc pairing with biometrics: SAfE. In 1st Int. Workshop on Security for Spontaneous Interaction (Ubicomp 2007 Workshop Proceedings), pages 450-456, Innsbruck, Austria, Sep 2007. http://www.comp.lancs.ac.uk/iwssi2007/papers/iwssi2007-02.pdf
Secure ad-hoc pairing • Suppose two people meet • Who have never met before • There is no TTP and/or they are not online • They are not technical • They would like to exchange data • Concerned about eavesdropper • How to do this? • Biometrics • Shielding function as fuzzy extractor • Protocol with novel “related key attack” IIS
wb wa Idea: Take each other’s photo Enroll- ment ma=0110... mb=1101... wa wb radio mb=decode( , ) Alice has ma,mb Verifi- cation ma=decode( , ) Bob has ma,mb IIS
Coping with noise • Problem: • Alice gets m’b close to mb but not the same • The same for Bob... • Solution: • During enrollment calculate error profiles • Cryptanalysis using those profiles to recover the correct key • More work for eavesdropper IIS
Usability • Compare Pin to SAFE • 30 subjects: questionnaire + interview • Mainly CS • Results IIS
Conclusions • Identification or verification • Complements password and token • Systems getting affordable • Biggest problems: • Performance • Public acceptance • Biometrics is fun IIS