@misc{cryptoeprint:2011:654,
author = {Laurie Haustenne and Quentin De Neyer and Olivier Pereira},
title = {Elliptic Curve Cryptography in JavaScript},
howpublished = {Cryptology ePrint Archive, Report 2011/654},
year = {2011},
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.