The importance of proofs of security for key establishment protocols : Formal analysis of Jan–Chen, Yang–Shen–Shieh, Kim–Huh–Hwang–Lee, Lin–Sun–Hwang, and Yeh–Sun protocols

Despite the importance of proofs in assuring protocol implementers about the security properties of key establishment protocols, many protocol designers fail to provide any proof of security. Flaws detected long after the publication and/or implementation of protocols will erode the credibility of key establishment protocols. We revisit recent work of Choo, Boyd, Hitchcock, Maitland where they utilize the Bellare, Pointcheval, Rogaway (Authenticated key exchange secure against dictionary attacks, in: B. Preneel (Ed.), Advances in Cryptology – Eurocrypt 2000, Springer-Verlag, LNCS 1807/2000, pp. 139–155, 2000) computational complexity proof model in a machine specification and analysis (using an automated model checker – SHVT) for provably secure key establishment protocol analysis. We then examine several key establishment protocols without proofs of security, namely: protocols due to J.-K. Jan, Y.-H. Chen (A new efficient MAKEP for wireless communications, in: 18th International Conference on Advanced Information Networking and Applications – AINA 2004, IEEE Computer Society, pp. 347–350, 2004), W.-H. Yang, J.-C. Shen, S.-P. Shieh (Designing authentication protocols against guessing attacks. Technical Report 2(3), Institute of Information & Computing Machinery, Taiwan, 1999. http://www.iicm.org.tw/communication/c2_3/page07.doc), Y.-S. Kim, E.-N. Huh, J. Hwang, B.-W. Lee (An efficient key agreement protocol for secure authentication, in: A. Laganà, M.L. Gavrilova, V. Kumar, Y. Mun, C.J.K. Tan, O. Gervasi (Eds.), International Conference On Computational Science And Its Applications – ICCSA 2004, Springer-Verlag, LNCS 3043/2004, pp. 746-754, 2004), C.-L. Lin, H.-M. Sun, T. Hwang. (Three-party encrypted key exchange: attacks and a solution, in: A CM SIGOPS Operating Systems Review, pp. 12–20, 2000), and H.-T. Yeh, H.-M. Sun (Simple authenticated key agreement protocol resistant to password guessing attacks, in: A CM SIGOPS Operating Systems Review, 36(4), pp. 14–22, 2002). Using these protocols as case studies, we demonstrate previously unpublished flaws in these protocols. We may speculate that such errors could have been found by protocol designers if proofs of security were to be constructed, and hope this work will encourage future protocol designers to provide proofs of security.