@misc{cryptoeprint:2004:303,
author = {Soonhak Kwon},
title = {Efficient Tate Pairing Computation for Supersingular Elliptic Curves over Binary Fields},
howpublished = {Cryptology ePrint Archive, Report 2004/303},
year = {2004},
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.