Cryptology ePrint Archive: BibTeX Citation of Report 2011/465

@misc{cryptoeprint:2011:465,
    author = {Craig Costello and Kristin Lauter and Michael Naehrig},
    title = {Attractive Subfamilies of BLS Curves for Implementing High-Security Pairings},
    howpublished = {Cryptology ePrint Archive, Report 2011/465},
    year = {2011},
    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.