Cryptology ePrint Archive: BibTeX Citation of Report 2015/068

@misc{cryptoeprint:2015:068,
    author = {Gregor Leander and Brice Minaud and Sondre Rønjom},
    title = {A Generic Approach to Invariant Subspace Attacks: Cryptanalysis of Robin, iSCREAM and Zorro},
    howpublished = {Cryptology ePrint Archive, Report 2015/068},
    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.