Cryptology ePrint Archive: BibTeX Citation of Report 2012/187

@misc{cryptoeprint:2012:187,
    author = {Alexandra Dmitrienko and Ahmad-Reza Sadeghi and Sandeep Tamrakar and Christian Wachsmann},
    title = {SmartTokens: Delegable Access Control with NFC-enabled Smartphones (Full Version)},
    howpublished = {Cryptology ePrint Archive, Report 2012/187},
    year = {2012},
    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.