Cryptology ePrint Archive: BibTeX Citation of Report 2004/243

@misc{cryptoeprint:2004:243,
    author = {Giuseppe Ateniese and Breno de Medeiros},
    title = {On the Key Exposure Problem in Chameleon Hashes},
    howpublished = {Cryptology ePrint Archive, Report 2004/243},
    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.