@misc{cryptoeprint:2006:031,
author = {Le Trieu Phong and Wakaha Ogata},
title = {On a Variation of Kurosawa-Desmedt Encryption Scheme},
howpublished = {Cryptology ePrint Archive, Report 2006/031},
year = {2006},
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.