1. A Risk Analysis Approach for Biometric Authentication Technology Author: Arslan Brömme Submission: International Journal of Network Security Speaker: Chun-Ta Li

2. 2 Outline  Introduction  Fundamentals  A High-Level Component & Process Model for Integrated Security Risk Analysis of Biometric Authentication Technology  A Holistic Security Risk Analysis Approach for Biometric Authentication Technology  Conclusions  Comments

3. 3 Introduction  Biometric technology Standardize data formats for biometric data interchange Standardize data formats for biometric data interchange Communication protocols Communication protocols Unified programming interface for enabling the interoperability of different biometric systems Unified programming interface for enabling the interoperability of different biometric systems Person authentication, identification and surveillance Person authentication, identification and surveillance  Risk analysis (core processes and components)

4. 4 Fundamentals  Risk analysis for biometric authentication technology IT security biometrics IT security biometrics Privacy Privacy Safety Safety Performance Performance Security risk analysis for biometric authentication technology Security risk analysis for biometric authentication technology  Biometric authentication systems

5. 5 Fundamentals (cont.)  IT security biometrics Studying on person recognition methods Studying on person recognition methods  Sensing of a person ’ s biological characteristics  Measuring of the captured or scanned biometrics  Computing of biometric signatures and biometric templates  Verifying and identifying against biometric templates  Privacy Privacy is everyone ’ s fundamental human right Privacy is everyone ’ s fundamental human right The principle of necessity of data collection means to avoid or at least to minimize personal data within an ICT system The principle of necessity of data collection means to avoid or at least to minimize personal data within an ICT system

6. 6 Fundamentals (cont.)  Safety/Performance risks Risk Risk  Failure and Fault Safety Safety  Risk degradation  Reliability and Availability ↑ Performance Performance  Throughput ↑  Latency ↓

7. 7 Fundamentals (cont.)  Security risk of biometric authentication technology The probability that a specific threat to biometric authentication technology The probability that a specific threat to biometric authentication technology  Security & Application Risk Traffic Light Model [Brunnstein 2003] Green: low probability Green: low probability Yellow : medium probability Yellow : medium probability Red : high probability Red : high probability A specific vulnerability of biometric authentication technology A specific vulnerability of biometric authentication technology

8. 8 Fundamentals (cont.)  Biometric Authentication Systems General authentication process [Brömme 2003] General authentication process [Brömme 2003]  Enrollment  Biometric authentication  Authroization  Access control  Derollment Basic elements Basic elements  Persons, hardware components, biometric communication channel, biometric process, biometric algorithms, biometric signature and biometric databases

9. 9 A High-Level Component & Process Model for Integrated Security Risk Analysis of Biometric Authentication Technology  High-level Component & Process Model for integrated Security Risk Analysis of Biometric Authentication Technology (ComProMiSe.Risk.of.BiT) sensing send receive (en|de)crypt query update write (en|de)rollment authentication capture transmission storage computation Biometric authentication technology High-level process components/function modules for high-level processes/function of high-level methods capture, transmission and storage (P) preprocessing (Q) quality check and enhancement (N) normalization (S) biometric signal processing (B) computation of Biometric signature (C) (cluster|classifi)cation (D) decision sub-level processes/functions sub-level processes components/functions modules lines of code scope of high-level component & process model high-level methods high-level processes/functions high-level process components/ Function modules

10. 10 A High-Level Component & Process Model for Integrated Security Risk Analysis of Biometric Authentication Technology (cont.)  Processes Enrollment, Authentication, Derollment Enrollment, Authentication, Derollment  Components P, Q, N, S, B, C, D P, Q, N, S, B, C, D  Risk aspect (1) security, privacy, safety, performance security, privacy, safety, performance  Risk aspect (2) attack, misuse, fault, failure attack, misuse, fault, failure

11. 11 A Holistic Security Risk Analysis Approach for Biometric Authentication Technology  Four potential risk interrelations : has potential risk effect : has potential risk effect : has risk effect : has risk effect : has no risk effect : has no risk effect : has no potential risk effect : has no potential risk effect  Two placeholders ★ : empty or Risk aspect (1) ★ : empty or Risk aspect (1) ◇ : empty or Risk aspect (2) ◇ : empty or Risk aspect (2)

12. 12 A Holistic Security Risk Analysis Approach for Biometric Authentication Technology (cont.)  Examples e ◇ ★ a (e faul safe a) e ◇ ★ a (e faul safe a) d ◇ ★ a (d attc secu a) d ◇ ★ a (d attc secu a) A less reliable enrollment process which has a potential safety risk effect on the authentication process resulting in the false recognition and/or acceptance of persons An attack for a derollment process which has a potential security risk effect on a subsequent authentication process can arise resulting for example in the non- derollment of the selected person or derollment of a third not selected person with the intention to later on false recognize and/or accept the person which should be derolled

13. 13 A Holistic Security Risk Analysis Approach for Biometric Authentication Technology (cont.)  Example eB attc secu aD eB attc secu aD  More than seven thousand 1 single possible risk effect classes given here  Flexibility of the ◇ ★ relation in combination with a risk matrix enables the systematic exploration and discussion of holistic security risks A possible risk attacks describes the manipulation of enrollment computations of biometric signatures for intended false acceptance of imposters and/or false rejection genuines in subsequent authentication attempts 1

14. 14 Conclusions  Author presents a systematic approach for a holistic security risk analysis of biometric authentication technology Processes & Components Processes & Components Four risk interrelations Four risk interrelations Biometric authentication risk matrices Biometric authentication risk matrices

15. 15 Comments  Evaluation of Paper Confirmatory Confirmatory  Recommendation Accept after minor revision Accept after minor revision  Details: In the proposed approach, there are eight risk aspects, three processes and eighteen components in the risk matrix, please briefly showed all of these process & components in the paper. In the proposed approach, there are eight risk aspects, three processes and eighteen components in the risk matrix, please briefly showed all of these process & components in the paper. In addition, there are four relations between elements. Are they enough to describe all of the risk effect for biometric authentication methods? Furthermore, how to define the condition of “ potential ” there should be described more clearly. In addition, there are four relations between elements. Are they enough to describe all of the risk effect for biometric authentication methods? Furthermore, how to define the condition of “ potential ” there should be described more clearly. In the risk matrix, how to define the interrelations between these elements. Are these relations are defined by users or the system? The author must briefly describe it. In the risk matrix, how to define the interrelations between these elements. Are these relations are defined by users or the system? The author must briefly describe it.

16. An Online Biometrics-based Secret Sharing Scheme for Multiparty Cryptosystem Using Smart Cards Advisor: Min-Shiang Hwang Speaker: Chun-Ta Li

17. 17 Notations UiUser SiSystem Ri A trusted registration center G A group of n users IDi Identity of user Bi Biometric template of user PWi The common password shared between Ui and Si QiQiQiQi An integer computed from PWi P A large prime S A secret key maintained by Si Rc i A random number generated by Ui Rs A random number generated by Si PKs Public key of Si H(.) One-way hashing function ⊕ XOR operation E PK {.} Asymmetric encryption with the public key PK E x [.] Symmetric encryption with the key x K Primary secret sharing key maintained by Si

18. 18 The Proposed Scheme  Registration phase G RiRiRiRi 1. ID i, B i, PW i 3. Computes X i = ID i f i mod P Computes e i = (y i S mod P) ⊕ X i Computes g i = X i SQ i mod P 4. Smart card (ID i, P, H(.), f i, e i, g i ) Secret channel // f i = H(H(B i )) // 2. Generates the Lagrange interpolating polynomial with degree t-1 (y i = K+a 1 x i +a 2 x i 2 + … + a t-1 x i t-1 mod P)

19. 19 The Proposed Scheme (cont.)  Reconstruction phase U1U1U1U1 SiSiSiSi U2U2U2U2 UtUtUtUt … 1. Every participant, U i (i = 1 to t), inserts his/her smart card and inputs B i into specific biometric device 2. Verifies H(H(B i )) = f i ? 3. If it holds, U i computes following messages X i ` = ID i fi mod P e i ` = e i ⊕ X i ` = y i S mod P M i1 = g i Q i -1 mod P = X i S mod P M i2 = (X i `) Q i mod P 4. U i sends his/her M i3 = E PKs {ID i ||M i1 ||M i2 ||Rc i } to S i

20. 20 The Proposed Scheme (cont.)  Reconstruction phase (cont.) U1U1U1U1 SiSiSiSi U2U2U2U2 UtUtUtUt … 8. If Step 7 holds, S i sends M i5 = E Rc [IDi||Rs||M i4 ] to U i 10. If Step 9 holds, U i sends M i6 = E Rs [ID i ||e i `] to S i 5. S i decrypts M i3 and checks the format of U i ’ s ID i 6. If it holds, S i computes M i4 = (M i2 ) Q i -1 mod P = X i ` mod P 7. Then, S i verifies (M i4 ) S = M i1 ? 9. U i decrypts M i5 and verifies M i4 = X i ` ?