@misc{cryptoeprint:2008:400,
author = {Yalin Chen and Hung-Min Sun and Chun-Hui Huang and Jue-Sam Chou},
title = {Comments on two password based protocols},
howpublished = {Cryptology ePrint Archive, Report 2008/400},
year = {2008},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.