@misc{cryptoeprint:2010:585,
author = {Daniel J. Bernstein and Tanja Lange and Christiane Peters},
title = {Smaller decoding exponents: ball-collision decoding},
howpublished = {Cryptology ePrint Archive, Report 2010/585},
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.