Cryptology ePrint Archive: BibTeX Citation of Report 2005/258

@misc{cryptoeprint:2005:258,
    author = {Nuttapong Attrapadung and Yang Cui and Goichiro Hanaoka and Hideki Imai and Kanta Matsuura and Peng Yang and Rui Zhang},
    title = {Relations Among Notions of Security for Identity Based Encryption Schemes},
    howpublished = {Cryptology ePrint Archive, Report 2005/258},
    year = {2005},
    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.