Cryptology ePrint Archive: BibTeX Citation of Report 2008/224

@misc{cryptoeprint:2008:224,
    author = {Hai Huang and Zhenfu Cao},
    title = {An ID-based Authenticated Key Exchange Protocol Based on Bilinear Diffie-Hellman Problem},
    howpublished = {Cryptology ePrint Archive, Report 2008/224},
    year = {2008},
    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.