Cryptology ePrint Archive: BibTeX Citation of Report 2013/206

@misc{cryptoeprint:2013:206,
    author = {Florian Kerschbaum and Hoon Wei Lim and Ivan Gudymenko},
    title = {Privacy-Preserving Billing for e-Ticketing Systems in Public Transportation},
    howpublished = {Cryptology ePrint Archive, Report 2013/206},
    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.