@misc{cryptoeprint:2007:172,
author = {Jan Camenisch and Susan Hohenberger and Michael {\O}stergaard Pedersen},
title = {Batch Verification of Short Signatures},
howpublished = {Cryptology ePrint Archive, Report 2007/172},
year = {2007},
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.