Cryptology ePrint Archive: BibTeX Citation of Report 2012/104

@misc{cryptoeprint:2012:104,
    author = {Wei Gao and Guilin Wang and Kefei Chen and Xueli Wang},
    title = {Provably Secure Generic Construction of Certificate Based Signature from Certificateless Signature in Standard Model},
    howpublished = {Cryptology ePrint Archive, Report 2012/104},
    year = {2012},
    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.