@misc{cryptoeprint:2010:644,
author = {Bo Zhu and Wenye Yu and Tao Wang},
title = {A Practical Platform for Cube-Attack-like Cryptanalyses},
howpublished = {Cryptology ePrint Archive, Report 2010/644},
year = {2010},
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.