Cryptology ePrint Archive: BibTeX Citation of Report 2013/683

@misc{cryptoeprint:2013:683,
    author = {Venkata Koppula and Kim Ramchen and Brent Waters},
    title = {Separations in Circular Security for Arbitrary Length Key Cycles},
    howpublished = {Cryptology ePrint Archive, Report 2013/683},
    year = {2013},
    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.