@misc{cryptoeprint:2008:065,
author = {Junghyun Nam},
title = {Infringing and Improving Password Security of a Three-Party Key Exchange Protocol},
howpublished = {Cryptology ePrint Archive, Report 2008/065},
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.