@misc{cryptoeprint:2015:659,
author = {Jean-Pierre Flori and Jérôme Plût and Jean-René Reinhard and Martin Ekerå},
title = {Diversity and Transparency for ECC},
howpublished = {Cryptology ePrint Archive, Report 2015/659},
year = {2015},
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.