Cryptology ePrint Archive: BibTeX Citation of Report 2009/211

@misc{cryptoeprint:2009:211,
    author = {Endre Bangerter and Stefania Barzan and Stephan Krenn and Ahmad-Reza Sadeghi and Thomas Schneider and Joe-Kai Tsay},
    title = {Bringing Zero-Knowledge Proofs of Knowledge to Practice},
    howpublished = {Cryptology ePrint Archive, Report 2009/211},
    year = {2009},
    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.