@misc{cryptoeprint:2001:039,
author = {Taekyoung Kwon},
title = {Robust Software Tokens: Towards Securing a Digital Identity},
howpublished = {Cryptology ePrint Archive, Report 2001/039},
year = {2001},
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.