@misc{cryptoeprint:2013:541,
author = {Zvika Brakerski and Vinod Vaikuntanathan},
title = {Lattice-Based FHE as Secure as PKE},
howpublished = {Cryptology ePrint Archive, Report 2013/541},
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.