@techreport{oai:ipsj.ixsq.nii.ac.jp:00044610, author = {辛星漢 and 古原和邦 and 今井, 秀樹 and SeongHan, SHIN and Kazukuni, KOBARA and Hideki, IMAI}, issue = {81(2006-CSEC-034)}, month = {Jul}, note = {Recently Viet et aL [21] have proposed an anonymous password-authenticated key exchange (PAKE) protocol against a passive server who follows the protocol honestly but it is curious about identity of client. In this paper we propose an efficient construction for anonymous PAKE protocol (we call it the EAP protocol) which provides semantic security of session keys in the random oracle model with the reduction to the computational Diffie-Hellman problem as well as anonymity against a passive server. Specially the EAP protocol has about 50% reduction (com pared to [21]) in the number of modular exponentiations for both client and server and its communication bandwidth for the modular size of prime p is independent from the number of clients while [21] is not., Recently, Viet et aL, [21] have proposed an anonymous password-authenticated key exchange (PAKE) protocol against a passive server, who follows the protocol honestly but it is curious about identity of client. In this paper, we propose an efficient construction for anonymous PAKE protocol (we call it the EAP protocol) which provides semantic security of session keys in the random oracle model, with the reduction to the computational Diffie-Hellman problem, as well as anonymity against a passive server. Specially, the EAP protocol has about 50% reduction (com pared to [21]) in the number of modular exponentiations for both client and server, and its communication bandwidth for the modular size of prime p is independent from the number of clients while [21] is not.}, title = {An Eflicient Anonymous Password - Authenticated Key EXchange Protocol}, year = {2006} }