Cryptology ePrint Archive: BibTeX Citation of Report 2002/009

@misc{cryptoeprint:2002:009,
    author = {Yongdae Kim and Adrian Perrig and Gene Tsudik},
    title = {Tree-based Group Key Agreement},
    howpublished = {Cryptology ePrint Archive, Report 2002/009},
    year = {2002},
    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.