Cryptology ePrint Archive: BibTeX Citation of Report 2004/259

@misc{cryptoeprint:2004:259,
    author = {An Braeken, Ventzislav Nikov, Svetla Nikova, Bart Preneel},
    title = {On Boolean Functions with Generalized Cryptographic Properties},
    howpublished = {Cryptology ePrint Archive, Report 2004/259},
    year = {2004},
    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.