Cryptology ePrint Archive: BibTeX Citation of Report 2010/209

@misc{cryptoeprint:2010:209,
    author = {Lei Zhang and Qianhong Wu and Bo Qin and Josep Domingo-Ferrer},
    title = {Identity-Based Authenticated Asymmetric Group Key Agreement Protocol},
    howpublished = {Cryptology ePrint Archive, Report 2010/209},
    year = {2010},
    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.