Cryptology ePrint Archive: BibTeX Citation of Report 2006/270

@misc{cryptoeprint:2006:270,
    author = {Guomin Yang and Duncan S. Wong and Huaxiong Wang and Xiaotie Deng},
    title = {Formal Analysis and Systematic Construction of Two-factor Authentication Scheme},
    howpublished = {Cryptology ePrint Archive, Report 2006/270},
    year = {2006},
    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.