Cryptology ePrint Archive: BibTeX Citation of Report 2013/234

@misc{cryptoeprint:2013:234,
    author = {Özgür Dagdelen and Marc Fischlin and  Tommaso Gagliardoni and Giorgia Azzurra Marson and Arno Mittelbach and Cristina Onete},
    title = {A Cryptographic Analysis of OPACITY},
    howpublished = {Cryptology ePrint Archive, Report 2013/234},
    year = {2013},
    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.