Cryptology ePrint Archive: BibTeX Citation of Report 2011/224

@misc{cryptoeprint:2011:224,
    author = {Xu An Wang and Liqiang Wu and Xiaoyuan Yang and Huaqun Wang},
    title = {Cryptanalysis and Improvement of an Efficient CCA Secure PKE Scheme},
    howpublished = {Cryptology ePrint Archive, Report 2011/224},
    year = {2011},
    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.