@misc{cryptoeprint:2006:110,
author = {F. Hess and N.P. Smart and F. Vercauteren},
title = {The Eta Pairing Revisited},
howpublished = {Cryptology ePrint Archive, Report 2006/110},
year = {2006},
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.