@misc{cryptoeprint:2012:192,
author = {Liangliang Xiao and I-Ling Yen and Dung T. Huynh},
title = {Extending Order Preserving Encryption for Multi-User Systems},
howpublished = {Cryptology ePrint Archive, Report 2012/192},
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.