Cryptology ePrint Archive: BibTeX Citation of Report 2011/634

@misc{cryptoeprint:2011:634,
    author = {Mohammad Sabzinejad Farash and Mahmoud Ahmadian Attari and Majid Bayat1},
    title = {Security of Multiple-Key Agreement Protocols and Propose an Enhanced Protocol},
    howpublished = {Cryptology ePrint Archive, Report 2011/634},
    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.