@misc{cryptoeprint:2008:202,
author = {Zhitu Su, Hui Li and JianFeng Ma},
title = {Polynomials for Ate Pairing and $\mathbf{Ate}_{i}$ Pairing},
howpublished = {Cryptology ePrint Archive, Report 2008/202},
year = {2008},
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.