Cryptology ePrint Archive: BibTeX Citation of Report 2015/233

@misc{cryptoeprint:2015:233,
    author = {Ben Smyth and Steven Frink and Michael R. Clarkson},
    title = {Election Verifiability: Cryptographic Definitions and an Analysis of Helios and JCJ},
    howpublished = {Cryptology ePrint Archive, Report 2015/233},
    year = {2015},
    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.