Cryptology ePrint Archive: BibTeX Citation of Report 2013/581

@misc{cryptoeprint:2013:581,
    author = {Bingsheng Zhang, Qin Zhan, Junfei Wang, Kui Ren, Cong Wang, Di Ma},
    title = {PriWhisper: Enabling Keyless Secure Acoustic Communication for Smartphones},
    howpublished = {Cryptology ePrint Archive, Report 2013/581},
    year = {2013},
    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.