@misc{cryptoeprint:2007:170,
author = {Stephane Lemieux and Adrian Tang},
title = {Clone Resistant Mutual Authentication for Low-Cost RFID Technology},
howpublished = {Cryptology ePrint Archive, Report 2007/170},
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.