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Telecommun Syst DOI 10.1007/s11235-010-9314-2 Privacy-preserving and tokenless chaotic revocable face authentication scheme Muhammad Khurram Khan · Khaled Alghathbar · Jiashu Zhang © Springer Science+Business Media, LLC 2010 Abstract With the large-scale proliferation of biometric 1 Introduction systems, privacy and irrevocability issues of their data have become a hot research issue. Recently, some researchers Recently, Biometrics-based person authentication systems proposed a couple of schemes to generate BioHash, e.g. have attracted much attention in implementing the security PalmHash, however, in this paper, we point out that the pre- of practical applications e.g. access control, e-commerce, vious schemes are costly in terms of computational com- and computer login, etc. [1]. Biometrics, i.e. something you plexity and possession of USB tokens to generate pseudo- are, has shown its superiority over the traditional authenti- random numbers. To overcome the problems, we propose a cation systems of passwords [something you know] and to- novel chaotic FaceHashing scheme which preserves privacy kens [something you have]. Biometrics data of a person is of a biometric user. The presented scheme does not need permanent, e.g. ﬁngerprint or face, and cannot be changed users to posses USB tokens in generating pseudorandom after a certain age. In case if biometric template or data is sequences, which is a cost-effective solution. Besides, our compromised then it can be misused to impersonate a valid scheme minimizes the system complexity with simple op- user, which could effect the integrity of the whole security erations to attain the FaceHash. Experimental results show system. The only remedy is to replace the theft data to an- that the proposed scheme is efﬁcient, secure, and revocable other biometrics template. But a person has limited num- in case FaceHash is theft or compromised. ber of biometrics traits e.g. one face and two irises, so it is not a feasible solution. It is very important to ﬁnd an al- ternative/substitute solution for the non-revocable biometric Keywords Face · Biometrics · Chaos · Authentication · technology. FaceHash · Security · Privacy To solve this problem, some researchers proposed a new approach that was named as BioHashing [2–8] that com- bines a tokenized random number and biometrics features. First, Connie et al. [2, 3] combined biometric palmprint fea- M.K. Khan ( ) · K. Alghathbar tures with a set of pseudorandom data to generate a unique Center of Excellence in Information Assurance (CoEIA), King Saud University, Riyadh, Kingdom of Saudi Arabia discretized code for every person. They performed inner e-mail: mkhurram@ksu.edu.sa product between palmprint features and pseudo random key and named their scheme as PalmHashing, which is the con- K. Alghathbar cept of palmprint + hashing technique. Information Systems Department, College of Computer and Information Sciences, King Saud University, Riyadh, Teoh-Ngo [4] proposed a two-factor authenticator based Kingdom of Saudi Arabia on iterated inner products between tokenized pseudo-random e-mail: kalghathbar@ksu.edu.sa number and the user speciﬁc ﬁngerprint feature, which gen- erated from the integrated wavelet and Fourier-Mellin trans- J. Zhang Sichuan Key Lab of Signal & Information Processing, form, and hence produce a set of user speciﬁc compact code Southwest Jiaotong University, Chengdu, Sichuan, P.R. China that coined as BioHashing. M.K. Khan et al. Teoh-Ngo [5] used the same concept to generate cance- scheme is composed of extracting the features from the cap- lable biometrics by human face. They proposed a face hash- tured biometrics face images to generate the face feature set, ing technique by performing the iterated inner products be- Generating chaotic pseudorandom numbers without using tween tokenized pseudorandom number and face features to the tokens, transforming the pseudorandom numbers into or- produce a speciﬁc code, which they named as FacceHash. thonormal vectors, performing inner products and deﬁning Recently, Maio-Nanni [6] and Nanni-Lumini [7] identi- the threshold, and ﬁnally the veriﬁcation of an identity. ﬁed that the above cited schemes show lower performance If the biometric data generated by our scheme is com- if an imposter B steals the pseudorandom numbers/key of promised, then user can be issued a new FaceHash and the a user A and tries to authenticate or impersonate as A. As same user can use different FaceHashes for different array of a consequence, Maio-Nanni [6] proposed a multimodal fu- applications e.g. National database, healthcare, and banking. sion of face and pseudorandom numbers, and claimed that So our scheme eliminates the fear of using biometrics for the their scheme can prevent the attacks in the case if B steals cross matching applications [1], and solves the problems of the pseudorandom numbers of A. Nanni-Lumini [7] also ex- non-revocable biometrics [8]. Moreover, proposed scheme tended their work on the basis of same idea by using hu- is general in nature and can be applied on any biometrics man signatures as a behavioral biometrics. They showed e.g. ﬁngerprint, iris, or signature to generate BioHash. that fusion of online signatures by combining with the to- Rest of the paper is organized as follows: Sect. 2 presents kenized pseudorandom numbers, generated by Blum-Blum- the proposed scheme, Sect. 3 elaborates the experimental re- Shub technique, could solve the security problem of previ- sults and discussion, and at the end, Sect. 4 concludes the ous schemes [2–7] when an impostor steals the pseudoran- ﬁndings of this paper. dom numbers of a legitimate user. However, in this paper, we point out that the all the pre- 2 The proposed scheme vious techniques use costly tokens e.g. USB to generate the pseudorandom numbers, which is a cost effective solution. The presented FaceHashing scheme is shown in Fig. 1 and All those schemes save the seed value on token and if the in the following subsections; we elaborate our scheme in token is compromised or stolen, an adversary can use it as detail. a valid user identity. Thus, those schemes suffer from the 2.1 Face feature vector generation problems of tokens because they can be lost, shared with others, and can be duplicated, etc. [17]. We also assume The proposed scheme starts with preprocessing face images that if these mentioned schemes are to be implemented in to generate feature vector. A 2D face image can be viewed as some sophisticated applications e.g. Automatic Teller Ma- a factor in the image space. Two sample face images, from chine (ATM) then, users cannot use their tokens to gener- ORL database [9], used in our experimentation are shown ate the pseudorandom numbers because of the limitations in in Fig. 2. A face gray image X with size M × N can be ATM machines. Besides, it is not a feasible solution to is- represented as: sue each user a speciﬁc USB to perform transactions on the ATMs. X = {x(i, j ), 0 ≤ i < M, 0 ≤ j < N } For the extension and improvement upon the related x(i, j ) ∈ {0, 1, . . . , 2L − 1} (1) schemes, we propose an efﬁcient and Tokenless technique in order to strengthen the privacy of biometric data. Our where L is the number of bits to represent a pixel. Fig. 1 Schematic diagram of the proposed scheme Privacy-preserving and tokenless chaotic revocable face authentication scheme For the feature extraction, we use a well-known tech- and symmetric property etc. These properties are signiﬁ- nique called principal component analysis (PCA), also cant in generating a sequence of independent and identically known as Eigenface for face recognition [10–12]. The ma- distributed binary random variables. The Jacobian Elliptic jor objective of PCA is to project the high dimensional vi- Chebyshev Rational Maps are rational functions deﬁned as sual stimuli i.e. face images into a lower dimensional space. follows [13]: PCA is an optimal method for dimensionality reduction in Let p be a positive integer, w ∈ [−1, 1] be a real number, the sense of mean-square error (MSE) [11, 12]. and k ∈ [0, 1] be a real number called modulus, then: Suppose the recognition space is y = {y1 , y2 , . . . , yn }T 2w and feature set is x = {x1 , x2 , . . . , xm }T , then the recogni- Rp+1 (w, k) = Rp (w, k) tion space becomes y = AT x, where AT is the transpose 1 − k 2 (1 − Rp (w, k)2 )(1 − w 2 ) matrix of A, which can be said transfer matrix, and n and − Rp−1 (w, k) (5) m are dimensions of recognition space and feature vector, respectively. The covariance of recognition space y can be where: p = 0, 1, 2, . . . , R0 (w, k) = 1 , and R1 (w, k) = w. shown as: The random vector generated by (5) is consisted of real 1 number entries distributed in the interval [−1, 1], which we σ 2 (A) = ¯ ¯ (y − y)T (y − y) = AT A (2) show as {β1 , β2 , β3 , . . . , βm }. n y∈Y 2.3 Vector orthonormalization ¯ ¯ where y is the average of y ∈ Y and is the covariance ma- trix of learning patterns, which can be mathematically rep- After generating the pseudorandom vector, we transform the resented as: basis {β1 , β2 , β3 , . . . , βm } into an orthonormal vector set by 1 the Gram-Schmidt process. The proof of Gram-Schmidt or- = ¯ ¯ (x − x)T (x − x) (3) n thonormalization can be shown as follows: x∈X def Let X = {β1 , β2 , β3 , . . . , βm } be a linearly independent ¯ ¯ where x is the average of x ∈ X. The above equation set of a n × 1 pseudorandom vectors with m ≤ n. If m < n can be used to solve the following eigenvalue problem then X may be ﬁlled out to a maximally linearly independent as: AT A = , where is a diagonal eigenvalue matrix vector set. Hence it is assumed that m = n, where X is a that has eigenvalues i.e. = diag{μ1 , μ2 , . . . , μ3 } and ∈ basis for C n . By Mathematical induction, we can deﬁne: R N ×N . And the cumulative proportion can be computed as: β1 m u1 = , i=1 μi β F= n × 100 (4) i=1 μi k where μi is the ith element eigenvalue of the diagonal ma- wk+1 = xk+1 − (xk+1 , ui )ui , (6) trix . Finally, the eigenvalues in decreasing order can be i=1 written as: μ1 ≥ μ2 ≥ · · · ≥ μm ≥ · · · ≥ μn and normalized wk+1 uk+1 = , k = 1, . . . , n − 1 face feature vector can be represented as α that is normal- wk+1 ized to a n × 1 vector. Then, 2.2 Chaotic pseudorandom vector generation (i) Since X is linearly independent x1 > 0 and so u1 is well deﬁned. Furthermore, u1 = 1. Sequences of independent and identically distributed (i.i.d.) (ii) Mathematical induction shows that: binary random variables have signiﬁcant applications in (a) Each wk+1 is a linear combination of x1 , . . . , xk+1 modern digital communication systems, such as spread and in this combination the coefﬁcient of xk+1 is 1, spectrum (SS) communication systems or cryptosystems hence not 0; [13, 14]. There is an immense surge in generating the (b) Each wk+1 = 0 and so the denominator in the deﬁ- pseudorandom sequences by chaotic nonlinear maps. Many nition of uk+1 is not 0, i.e. uk+1 is well deﬁned and researchers have proposed different techniques of gener- uk+1 = 1. ating pseudorandom sequences for the secure applications (iii) [13–15, 19]. Khoda and Fujisaki [13] have shown that Ja- cobian elliptic Chebyshev rational map is a good candi- (w2 , u1 ) = (x2 − (x2 , u1 )u1 , u1 ) date in generating the true i.i.d pseudorandom sequences. = (x2 , u1 ) − (x2 , u1 )(u1 , u1 ) This map has many properties e.g. absolutely continuous in- variant (ACI) measure property, equi-distributivity property, = (x2 , u1 ) − (x2 , u1 )1 = 0 (7) M.K. Khan et al. Fig. 2 Sample face images from ORL Database More generally, if we assume that: 2.5 Template veriﬁcation 1, i = j ≤ k (ui , uj ) = If a person has to verify himself as a legitimate user, then 0, i = j, i, j ≤ k the proposed system generates a FaceHash by the scheme then, described as above, and matching between the hashed tem- plates can be done by the following equation: k (wk+1 , uj ) = xk+1 − (xk+1 , ui )ui , uj 1 N i=1 M= bi ⊕ bi (10) N i=1 k = (xk+1 , uj ) − (xk+1 , uj )(ui , uj ) where, N is the size of the FaceHash template, bi is i=1 FaceHash-ed template stored in the database, while bi is = (xk+1 , uj ) − (xk+1 , uj )(uj , uj ) a newly generated template for veriﬁcation. = (xk+1 , uj ) − (xk+1 , uj )1 = 0 def 3 Experimental results Hence, (uk+1 , uj ) = 0 if j ≤ k and X = {u1 , u2 , u3 , . . . , un } is an orthonormal set of vectors. In this section, we provide experimental results and dis- cussions on the proposed scheme. We evaluate the per- 2.4 Inner product and thresholding formance of presented method by using the ORL face database [9]. The database consists of 400 images ac- def Now, we perform the inner product of the X = {u1 , u2 , u3 , quired from 40 persons with variations in facial expressions . . . , un } orthonormal vector set with the normalized face fea- (e.g. open/close eyes, smiling/non-smiling), and facial de- ture vector i.e. α by the following equation: tails (e.g. with wearing glasses/without wearing glasses). All images were taken under a dark background with a χ = ( α, u1 , α, u2 , . . . , α, un ) (8) 92 × 112 pixels resolution. Figure 2 shows two individ- ual samples in ORL database. In the following subsec- After that, we perform the threshold of vector χ by the fol- tions, we perform experimentation and discuss their re- lowing equation: sults. 1 α, ui > λ bi = (9) 3.1 Biometric revocation 0 α, ui ≤ λ where bi is a revocable biometrics-face Hash, and λ is a The results shown in Fig. 3 and Fig. 4 indicate that the pro- threshold value such that on average half bits are zeros and posed FaceHash scheme is very sensitive and a tiny amount half bits are ones. At the end, this biometrics FaceHash can of change in the seed value can abruptly change the be- be issued to the user and saved in the database or token e.g. havior of the system. As an example, we used the seed smart card. w0 = ABEF28E9CA, but when we modify slightly differ- Privacy-preserving and tokenless chaotic revocable face authentication scheme Fig. 3 Key sensitivity simulation. (a) When seed w0 = ABEF28E9CA, (b) When seed w0 = ABEF28E9CB Fig. 4 Diffusion of FaceHashing at two different seeds. (a) Diffusion when seed w0 = 3839384B4. (b) Diffusion when seed w0 = 3839384B3 ent value of the seed i.e., replace the last alphabet A with B, 3.2 Statistical analysis w0 = ABEF28E9CB, then the recovered FaceHash is differ- ent as shown in Fig. 3(b). In order to hide message redundancy, Shannon introduced The diffusion of FaceHash at two different seeds is also diffusion and confusion. These two general principles guide shown in Fig. 4. to the design of practical cipher, including Hash functions [15, 18]. For the FaceHash in binary format the ideal diffu- Hence, our proposed FaceHash is very sensitive to a sion effect should be that any tiny changes in initial condi- small change in the seed key and without knowing the seed; tions lead to the 50% changing probability of each bit. For it is very difﬁcult to generate the same FaceHash. Thus, pre- surveying the performance of diffusion and confusion, we sented scheme solves the non-revocability problem of bio- performed the statistical test. If a bit in the seed is randomly metric templates and a user can be easily issued a new Face- selected and toggled, and a new hash value is generated, Hash in the case his previous FaceHash is lost, compro- then two FaceHash values are compared and the number of mised, or theft. Furthermore, our scheme allows generating changed bit is counted as Bi . This kind of test is performed different FaceHashes for different array of applications to N times, and the corresponding distribution of Bi is shown maintain the privacy of an individual [1]. in Fig. 5, where N = 2048. M.K. Khan et al. Fig. 5 Distribution of changed bits Bi If the size of hash is 128 bits, then one bit changed in Table 1 Number of changed bits Bi the seed concentrates around the ideal changed bit number- N = 512 N = 1024 N = 2048 64bit. It shows that the FaceHash has very strong capability for diffusion and confusion. Statistical analysis is evaluated Bmin 44 46 46 by the following equations [14]: Bmax 81 81 80 ¯ B 63.97 63.94 63.90 Bmin = min({Bi }N ), 1 denotes the minimum of Bi (11) B 5.56 5.30 5.58 Bmax = max({Bi }N ), 1 denotes the maximum of Bi (12) P (%) 49.95 49.95 49.92 P (%) 4.32 4.15 4.36 N ¯ 1 B= Bi , denotes the mean of Bi (13) N i=1 schemes did not discuss the statistical analysis of their gen- N 1 ¯ erated Hashes, so it is difﬁcult to judge the trueness e.g. con- B= (Bi − B)2 , N −1 fusion and diffusion properties of their BioHashes. i=1 denotes the standard variance of Bi (14) 3.3 FAR and FRR ¯ P = (B/128) × 100%, ¯ denotes the probability of B (15) The performance of the proposed system is measured by N 1 false acceptance rate (FAR) and false rejection rate (FRR). P= (Bi /128 − P )2 , N FAR is the rate, at which an imposter generates the same i=1 FaceHash of a legitimate user. FRR is the rate, at which an denotes the standard variance of P (16) authentic user generates a FaceHash other than his original one. FAR and FRR can be written as: Through the tests with N = 512, 1024, 2048, respectively, the corresponding data are listed in Table 1. FAR = ρ(μn |fI )dx; FRR = ρ(μn |fA )dx Based on the analysis of the data in Table 1, we can draw the conclusion that the mean changed bit number B and ¯ the mean changed probability P are both very close to the where ρ(μ|f ) is the probability distribution function (PDF) ideal value 64 bit and 50%. While B and P are very of the face features vector f = [f1 , f2 , . . . , fn ], n is the little, which indicates the capability for diffusion and con- number of features, and μn is a given class of n = 1, fusion of our FaceHash is very stable. Besides, all previous 2, . . . , N, N + 1. By computing the following likelihood ra- Privacy-preserving and tokenless chaotic revocable face authentication scheme tio, we compute acceptance or rejection strategy [16]: References ρ(μn |f ) ρ(μn ) = log (17) 1. Jain, A. K., Ross, A., & Prabhakar, S. (2004). An introduction to ρ(μN +1 |f ) biometric recognition. IEEE Transactions on Circuits and Systems for Video Technology, 14, 4–20. where μN +1 is the imposters class. By using logarithm’s 2. Connie, T., Teoh, T., Goh, M., & Ngo, D. (2004). PalmHashing: property i.e. log a = log a − log b, (16) becomes: b a novel approach for dual-factor authentication. Pattern Analysis Applications, 7, 255–268. ρ(μn ) = log ρ(μn |f ) − log(ρ(μN +1 |f )) (18) 3. Connie, T., Teoh, T., Goh, M., & Ngo, D. (2005). PalmHashing: a novel approach to cancelable biometrics. Information Processing Now ﬁrst we compute the following: Letters, 93, 1–5. 4. Jin, A.T.B, Ling, D.N.C., & Goh, M. (2004). BioHashing: two fac- μ = arg max ρ(μn ) (19) tor authentication featuring ﬁngerprint data and tokenized random μ1 ,...,μN number. Pattern Recognition, 37, 2245–2255. 5. Jin, A.T.B, Ling, D.N.C. (2005). Cancellable biometrics featuring At the end, acceptance or rejection can be performed by the with tokenised random number. Pattern Recognition Letters, 26, following threshold: 1454–1460. 6. Maio, D., & Nanni, L. (2005). MultiHashing human authentica- if ρ(μ ) ≥ τ Accept tion featuring biometrics data and tokenised random number: a D= (20) case study FVC2004. Neurocomputing, 69, 242–249. if ρ(μ ) < τ Otherwise 7. Nanni, L., & Lumini, A. (2006). Human, authentication featuring signatures and tokenized random numbers. Neurocomputing, 69, where τ is a decision threshold, and can be deﬁned accord- 858–861. ing to the criticality of the biometric system. 8. David, N. C. L., Andrew, T. B. J., & Alwyn, G. (2006). Biomet- ric hash: high conﬁdence face recognition. IEEE Transactions on 3.4 Analysis of computational complexity and efﬁciency Circuits and Systems for Video Technology, 16, 771–775. 9. ORL (1992). The ORL face database. at the AT&T (Olivetti) Re- All the previous schemes generate pseudorandom sequences search Laboratory. Available online: http://www.uk.research.att. com/facedatabase.html. by using tokens e.g. USB, which is a very costly solution. 10. Turk, M. A. (1991). Eignefaces for recognition. Journal of Cogni- Generally, if USB connectors are embedded in biometric tive Neuroscience, 3, 71–86. sensors, it would increase the overall cost and these are not 11. Martinez, A. M., & Kak, A. C. (2001). PCA versus LDA. IEEE commonly available. Here, we assume that if these schemes Transactions on Pattern Analysis and Machine Intelligence, 23, 228–233. are to be implemented in some sophisticated applications 12. Nara, Y., Ran, J., & Suematsu, Y. (2004). Face recognition using e.g. Automatic Teller Machine (ATM) then, users cannot use improved principal component analysis. In IEEE int. symposium their USBs to generate pseudorandom numbers because of on micrometaronics and human science (pp. 77–82). the limitations in ATM machines. Besides, it is not a feasi- 13. Kohda, T., & Fujisaki, T. (2001). Jacobian elliptic Chebyshev ra- ble solution to issue each user a speciﬁc USB to generate tional maps. Physics D, 148, 242–254. 14. Khan, M.K, Zhang, J., & Lei, T. (2007). Chaotic secure content- pseudorandom numbers in performing banking transactions based hidden transmission of biometrics templates. Chaos, Soli- on the ATMs. In our scheme, a user does not need to possess tons, and Fractals, 32, 1749–1759. tokens, e.g. USB, to generate the pseudorandom sequences 15. Xiao, D., Xiaofeng, L., & Shaojiang, D. (2005). One-way Hash because the sequence generator is built-in the system and all function construction based on the chaotic map with changeable- parameter. Chaos, Solitons and Fractals, 24, 65–71. the processing is done by the presented algorithm. 16. Erzin, E., Yemez, Y., & Tekalp, A. M. (2006). Multimodal person recognition for human-vehicle interaction. IEEE Multimedia, 18- 31. 4 Conclusion 17. Adams, K., Cheung, K.H., Zhang, D., Mohamed, K., & Jane, Y. (2006). An analysis of BioHashing and its invariants. Pattern In this paper, we have presented a novel approach of gen- Recognition, 39, 1359–1968. 18. Khan, M.K, Zhang, J. (2008). Chaotic hash-based ﬁngerprint erating FaceHashes to maintain the privacy of a biometric biometric remote user authentication scheme on mobile devices. user. Firstly, we pointed out pitfalls and weaknesses of the Chaos, Solitons and Fractals, 35, 519–524. previous schemes, e.g. use of USB to generate pseudoran- 19. Kia, F., Reza, R., & Hossein, K. (2008). An application of Chen dom numbers, and then, we proposed an efﬁcient solution system for secure chaotic communication based on extended Kalman ﬁlter and multi-shift cipher algorithm. Communications to overcome the irrevocability problem of face-biometric in Nonlinear Science and Numerical Simulation, 13, 763–781. data by performing simple operations to generate FaceHash without using the USB token. Experimental and simulation results have shown that the presented approach is secure, robust, computationally feasible, and cost-ineffective to at- tain the revocable face-biometrics authentication. Our future work will focus on the multimodal BioHashing schemes and their applications in the real environment. M.K. Khan et al. Muhammad Khurram Khan is Khaled Alghathbar Khaled Al- currently working as Assistant Pro- ghathbar, Ph.D., CISSP, CISM, PMP, fessor at Center of Excellence in MCSE: Security, Security+, BS7799 Information Assurance (CoEIA), Lead Auditor, is an associate pro- King Saud University, Saudi Ara- fessor and the director of the Center bia. He is the Founding Editor of of Excellence in Information As- ‘Bahria University Journal of In- surance in King Saud University, formation & Communication Tech- Riyadh, Saudi Arabia. He is a se- nology (BUJICT)’. He also plays curity advisor for several govern- role of Editor of several interna- ment agencies. His main research tional journals of Elsevier Science interest is in information security and Springer-Verlag. He has been management, policies and design. the Program Chair and Publica- He received his Ph.D. in Informa- tion Chair of 12th IEEE Interna- tion Technology from George Ma- tional Multitopic Conference (IN- son University, USA. MIC’08). He has also been the Program Chair of the IEEE International Symposium on Biometrics & Security Technologies (ISBAST’08). Jiashu Zhang received the B.S. de- He has worked as General Chair for the International Workshop on gree in electronic engineering from Frontiers of Information Assurance and Security (FIAS’09), Aus- the University of electronic science tralia. Furthermore, he performed duties of Publicity Co-Chair of 6th and technology of China, Chengdu, International Conference on Intelligent Computing (ICIC’10), Pub- P.R. China in 1987, and the M.S. de- licity Co-Chair of 5th International Conference on Intelligent Com- gree in biomedical engineering and puting (ICIC’09), International Conference on Security Technology instruments from Chongqing Uni- (SecTech’09), International Conference on Ubiquitous Computing and versity in 1990, and the Ph.D. de- Multimedia Applications (UCMA’10). He is an advisory board of gree in communication and infor- 2nd International Conference on Advanced Science and Technology mation system form University of (AST’10). Moreover, he is workshop management chair of 4th Inter- electronic science and technology national Conference on Information Security and Assurance (ISA’10). of China, Chengdu, P.R. China in He also works as the Program Committee Member of ICPR’10, 2001. He is currently a full profes- ICWAPR’10, AICCSA’10, ICIC’10, PDCAT’09, ACSA’09, RISC’09, sor of information and communica- ICWAPR’09, ScalCom’09, ICIC’09, ICIC’08, ICPADS’08, HPCC’08, tion engineering in the school of in- ICWAPR’08, ICIC’07, and ICIC’06. Besides, he is a reviewer of sev- formation science and technology at Southwest Jiaotong University, eral international journals and conferences. Recently, he has been Chengdu, P.R. China. His current research interests are in the areas of awarded outstanding leadership award at IEEE NSS’09 conference biometric and information security, signal processing for communica- in October, 2009 at Australia. He has been recently included in the tion, nonlinear system and chaos. Marquis Who’s Who in the World 2010 edition. Dr. Khurram has pub- lished more than 50 research papers in the journals and conferences of international repute. His areas of interest are biometrics, information security, multimedia security, and digital data hiding.

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