@misc{cryptoeprint:2009:440,
author = {Albrecht Petzoldt and Johannes Buchmann},
title = {A Multivariate Signature Scheme with an almost cyclic public key},
howpublished = {Cryptology ePrint Archive, Report 2009/440},
year = {2009},
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.