@misc{cryptoeprint:2009:096,
author = {M.I. Gonzalez Vasco and A. L. Perez del Pozo and P. Taborda Duarte},
title = {A note on the security of MST3},
howpublished = {Cryptology ePrint Archive, Report 2009/096},
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.