Cryptology ePrint Archive: BibTeX Citation of Report 2011/685

@misc{cryptoeprint:2011:685,
    author = {Roman Oliynykov},
    title = {Cryptanalysis of Symmetric Block Ciphers Based on the Feistel Network with Non-bijective S-boxes in the Round Function},
    howpublished = {Cryptology ePrint Archive, Report 2011/685},
    year = {2011},
    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.