Cryptology ePrint Archive: BibTeX Citation of Report 2007/270

@misc{cryptoeprint:2007:270,
    author = {David Chaum and Jeroen van de Graaf and Peter Y. A. Ryan and Poorvi L. Vora},
    title = {Secret Ballot Elections with Unconditional Integrity},
    howpublished = {Cryptology ePrint Archive, Report 2007/270},
    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.