Cryptology ePrint Archive: BibTeX Citation of Report 2004/261

@misc{cryptoeprint:2004:261,
    author = {Dan Boneh and Jonathan Katz},
    title = {Improved Efficiency for CCA-Secure Cryptosystems Built Using Identity-Based Encryption},
    howpublished = {Cryptology ePrint Archive, Report 2004/261},
    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.