@misc{cryptoeprint:2009:605,
author = {Xavier Pujol and Damien Stehle},
title = {Solving the Shortest Lattice Vector Problem in Time 2^2.465n},
howpublished = {Cryptology ePrint Archive, Report 2009/605},
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.