@misc{cryptoeprint:2013:448,
author = {Yuval Yarom and Katrina Falkner},
title = {Flush+Reload: a High Resolution, Low Noise, L3 Cache Side-Channel Attack},
howpublished = {Cryptology ePrint Archive, Report 2013/448},
year = {2013},
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.