@misc{cryptoeprint:2002:114,
author = {N.P. Smart and J. Westwood},
title = {Point Multiplication on Ordinary Elliptic Curves over Fields of Characteristic Three},
howpublished = {Cryptology ePrint Archive, Report 2002/114},
year = {2002},
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.