Cryptology ePrint Archive: BibTeX Citation of Report 2007/414

@misc{cryptoeprint:2007:414,
    author = {Daniel J. Bernstein and Peter Birkner and Tanja Lange and Christiane Peters},
    title = {Optimizing double-base elliptic-curve single-scalar multiplication},
    howpublished = {Cryptology ePrint Archive, Report 2007/414},
    year = {2007},
    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.