@misc{cryptoeprint:2009:451,
author = {Georg Lippold, Colin Boyd, Juan Gonz\'{a}lez Nieto},
title = {Efficient Certificateless KEM in the Standard Model},
howpublished = {Cryptology ePrint Archive, Report 2009/451},
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.