@misc{cryptoeprint:2009:539,
author = {Yupeng Jiang and Yingpu Deng and Yanbin Pan},
title = {Covering Radius of Two-dimensional Lattices},
howpublished = {Cryptology ePrint Archive, Report 2009/539},
year = {2009},
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.