@misc{cryptoeprint:2009:086,
author = {P. N. J. Eagle and Steven D. Galbraith and John Ong},
title = {Point Compression for Koblitz Elliptic Curves},
howpublished = {Cryptology ePrint Archive, Report 2009/086},
year = {2009},
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.