Cryptology ePrint Archive: BibTeX Citation of Report 2011/451

@misc{cryptoeprint:2011:451,
    author = {Hakhyun Kim, Woongryul Jeon, Yunho Lee and Dongho Won},
    title = {Cryptanalysis and improvement of a biometrics-based multi-server authentication with key agreement scheme},
    howpublished = {Cryptology ePrint Archive, Report 2011/451},
    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.