@misc{cryptoeprint:2012:657,
author = {Sungwook Kim and Jung Hee Cheon},
title = {Fixed Argument Pairing Inversion on Elliptic Curves},
howpublished = {Cryptology ePrint Archive, Report 2012/657},
year = {2012},
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.