Cryptology ePrint Archive: BibTeX Citation of Report 2009/222

@misc{cryptoeprint:2009:222,
    author = {Willi Geiselmann and Kenneth Matheis and Rainer Steinwandt},
    title = {PET SNAKE: A Special Purpose Architecture to Implement an Algebraic Attack in Hardware},
    howpublished = {Cryptology ePrint Archive, Report 2009/222},
    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.