Cryptology ePrint Archive: BibTeX Citation of Report 2001/088

@misc{cryptoeprint:2001:088,
    author = {Ignacio Gracia and Sebastià Martín and Carles Padró},
    title = {Improving the trade-off between storage and communication in broadcast encryption schemes},
    howpublished = {Cryptology ePrint Archive, Report 2001/088},
    year = {2001},
    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.