Cryptology ePrint Archive: BibTeX Citation of Report 2012/510

@misc{cryptoeprint:2012:510,
    author = {Sebastian Kutzner and  Phuong Ha Nguyen and Axel Poschmann},
    title = {Enabling 3-share Threshold Implementations for any 4-bit S-box},
    howpublished = {Cryptology ePrint Archive, Report 2012/510},
    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.