Cryptology ePrint Archive: BibTeX Citation of Report 2015/1004

@misc{cryptoeprint:2015:1004,
    author = {Shinya Okumura and Shingo Sugiyama and Masaya Yasuda and Tsuyoshi Takagi},
    title = {Security Analysis of Cryptosystems Using Short Generators over Ideal Lattices},
    howpublished = {Cryptology ePrint Archive, Report 2015/1004},
    year = {2015},
    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.