Cryptology ePrint Archive: BibTeX Citation of Report 2004/257

@misc{cryptoeprint:2004:257,
    author = {Junghyun Nam, Seungjoo Kim, and Dongho Won},
    title = {A Weakness in Jung-Paeng-Kim's ID-based Conference Key Distribution Scheme},
    howpublished = {Cryptology ePrint Archive, Report 2004/257},
    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.