@misc{cryptoeprint:2009:598,
author = {L. Chen, D. Page and N.P. Smart},
title = {On the Design and Implementation of an Efficient DAA Scheme},
howpublished = {Cryptology ePrint Archive, Report 2009/598},
year = {2009},
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.