@misc{cryptoeprint:2008:366,
author = {Than Quang Khoat and Nguyen Hong Tan},
title = {Unique Shortest Vector Problem for max norm is NP-hard},
howpublished = {Cryptology ePrint Archive, Report 2008/366},
year = {2008},
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.