Cryptology ePrint Archive: BibTeX Citation of Report 2015/221

@misc{cryptoeprint:2015:221,
    author = {Daniel J. Bernstein and Tanja Lange and Christine van Vredendaal},
    title = {Tighter, faster, simpler side-channel security evaluations beyond computing power},
    howpublished = {Cryptology ePrint Archive, Report 2015/221},
    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.