@misc{cryptoeprint:2006:288,
author = {Onur Aciicmez and Jean-Pierre Seifert and Cetin Kaya Koc},
title = {Predicting Secret Keys via Branch Prediction},
howpublished = {Cryptology ePrint Archive, Report 2006/288},
year = {2006},
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.