@misc{cryptoeprint:2012:427,
author = {Robert Drylo},
title = {Constructing Pairing-Friendly Genus 2 Curves with Split Jacobian},
howpublished = {Cryptology ePrint Archive, Report 2012/427},
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.