@misc{cryptoeprint:2012:478,
author = {Wang Qinglong, Xu Li},
title = {Cryptanalysis on a novel unconditionally secure oblivious polynomial evaluation protocol},
howpublished = {Cryptology ePrint Archive, Report 2012/478},
year = {2012},
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.