Cryptology ePrint Archive: BibTeX Citation of Report 2014/681

@misc{cryptoeprint:2014:681,
    author = {Mohamed Ahmed Abdelraheem, Javad Alizadeh, Hoda A. Alkhzaimi, Mohammad Reza Aref, Nasour Bagheri, Praveen Gauravaram, and Martin M. Lauridsen},
    title = {Improved Linear Cryptanalysis of Reduced-round SIMON},
    howpublished = {Cryptology ePrint Archive, Report 2014/681},
    year = {2014},
    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.