Cryptology ePrint Archive: BibTeX Citation of Report 2012/439

@misc{cryptoeprint:2012:439,
    author = {Ding Wang, Ping Wang, Chun-guang Ma, Zhong Chen },
    title = {Robust Smart Card based Password Authentication Scheme against Smart Card Security Breach},
    howpublished = {Cryptology ePrint Archive, Report 2012/439},
    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.