@misc{cryptoeprint:2010:364,
author = {Jean-Luc Beuchat and Eiji Okamoto and Teppei Yamazaki},
title = {A Compact FPGA Implementation of the SHA-3 Candidate ECHO},
howpublished = {Cryptology ePrint Archive, Report 2010/364},
year = {2010},
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.