@misc{cryptoeprint:2007:310,
author = {Kwang Ho Kim},
title = {A Note on Point Multiplication on Supersingular Elliptic Curves over Ternary Fields},
howpublished = {Cryptology ePrint Archive, Report 2007/310},
year = {2007},
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.