Cryptology ePrint Archive: BibTeX Citation of Report 2015/040

@misc{cryptoeprint:2015:040,
    author = {Zahra Ahmadian and Shahram Rasoolzadeh and Mahmoud Salmasizadeh and Mohammad Reza Aref},
    title = {Automated Dynamic Cube Attack on Block Ciphers: Cryptanalysis of SIMON and KATAN},
    howpublished = {Cryptology ePrint Archive, Report 2015/040},
    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.