@misc{cryptoeprint:2002:187,
author = {Herv\'e SIBERT and Patrick DEHORNOY and Marc GIRAULT},
title = {Entity Authentication Schemes Using Braid Word Reduction},
howpublished = {Cryptology ePrint Archive, Report 2002/187},
year = {2002},
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.