Cryptology ePrint Archive: BibTeX Citation of Report 2008/470

@misc{cryptoeprint:2008:470,
    author = {Paolo D'Arco and Alfredo De Santis},
    title = {From Weaknesses to Secret Disclosure in a Recent Ultra-Lightweight  RFID Authentication Protocol},
    howpublished = {Cryptology ePrint Archive, Report 2008/470},
    year = {2008},
    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.