@misc{cryptoeprint:2007:244,
author = {Martin Hlavac and Tomas Rosa},
title = {A Note on the Relay Attacks on e-passports: The Case of Czech e-passports},
howpublished = {Cryptology ePrint Archive, Report 2007/244},
year = {2007},
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.