@misc{cryptoeprint:2010:268,
author = {HU Mengke; GAO Juntao},
title = {Key-Controlled Order-Preserving Encryption},
howpublished = {Cryptology ePrint Archive, Report 2010/268},
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.