Cryptology ePrint Archive: BibTeX Citation of Report 2009/245

@misc{cryptoeprint:2009:245,
    author = {Naoki Ogura and Shigenori Uchiyama},
    title = {Cryptanalysis of the Birational Permutation Signature Scheme over a Non-commutative Ring},
    howpublished = {Cryptology ePrint Archive, Report 2009/245},
    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.