@misc{cryptoeprint:2011:594,
author = {Dalia Khader and Peter Y.A. Ryan},
title = {Receipt Freeness of Prêt à Voter Provably Secure},
howpublished = {Cryptology ePrint Archive, Report 2011/594},
year = {2011},
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.