@misc{cryptoeprint:2013:657,
author = {Sarah Meiklejohn and Hovav Shacham},
title = {New Trapdoor Projection Maps for Composite-Order Bilinear Groups},
howpublished = {Cryptology ePrint Archive, Report 2013/657},
year = {2013},
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.