@misc{cryptoeprint:2009:054,
author = {Ewan Fleischmann and Michael Gorski and Stefan Lucks},
title = {On the Security of Tandem-DM},
howpublished = {Cryptology ePrint Archive, Report 2009/054},
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.