Cryptanalysis and enhancement of a chaotic maps-based three-party password authenticated key exchange protocol

Recently, Lee et al. (Nonlinear Dyn, 73(1-2):125-132, 2013) proposed a three party password authenticated key exchange with user anonymity by utilizing extended chaotic maps. They claimed that their protocol is more secure than previously proposed schemes. In this paper, our analysis shows that Lee et al.'s protocol suffers from two kinds of attacks: (1) man-in-the-middle attack, and (2) user anonymity attack. To overcome these weakness, we propose an enhanced protocol that can resist the attacks described and yet with comparable efficiency.