@misc{cryptoeprint:2003:018,
author = {HO-KYU LEE, HYANG-SOOK LEE, YOUNG-RAN LEE},
title = {An Authenticated Group Key Agreement Protocol on Braid groups},
howpublished = {Cryptology ePrint Archive, Report 2003/018},
year = {2003},
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.