Cryptology ePrint Archive: BibTeX Citation of Report 2005/015

@misc{cryptoeprint:2005:015,
    author = {Dan Boneh and Xavier Boyen and Eu-Jin Goh},
    title = {Hierarchical Identity Based Encryption with Constant Size Ciphertext},
    howpublished = {Cryptology ePrint Archive, Report 2005/015},
    year = {2005},
    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.