Cryptology ePrint Archive: BibTeX Citation of Report 2007/161

@misc{cryptoeprint:2007:161,
    author = {Ling Cheung and Joseph A. Cooley and Roger Khazan and Calvin Newport},
    title = {Collusion-Resistant Group Key Management Using Attribute-Based Encryption},
    howpublished = {Cryptology ePrint Archive, Report 2007/161},
    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.