Cryptology ePrint Archive: BibTeX Citation of Report 2015/255

@misc{cryptoeprint:2015:255,
    author = {David Bernhard and Veronique Cortier and David Galindo and Olivier Pereira and Bogdan Warinschi},
    title = {A comprehensive analysis of game-based ballot privacy definitions},
    howpublished = {Cryptology ePrint Archive, Report 2015/255},
    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.