Cryptology ePrint Archive: BibTeX Citation of Report 2010/420

@misc{cryptoeprint:2010:420,
    author = {Stanislav Bulygin and Albrecht Petzoldt and Johannes Buchmann},
    title = {Towards provable security of the Unbalanced Oil and Vinegar signature scheme under direct attacks},
    howpublished = {Cryptology ePrint Archive, Report 2010/420},
    year = {2010},
    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.