Cryptology ePrint Archive: BibTeX Citation of Report 2007/323

@misc{cryptoeprint:2007:323,
    author = {Rafail Ostrovsky and Amit Sahai and Brent Waters},
    title = {Attribute-Based Encryption with Non-Monotonic Access Structures},
    howpublished = {Cryptology ePrint Archive, Report 2007/323},
    year = {2007},
    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.