Cryptology ePrint Archive: BibTeX Citation of Report 2015/247

@misc{cryptoeprint:2015:247,
    author = {Paulo S. L. M. Barreto and Craig Costello and Rafael Misoczki and Michael Naehrig and Geovandro C. C. F. Pereira and Gustavo Zanon},
    title = {Subgroup security in pairing-based cryptography},
    howpublished = {Cryptology ePrint Archive, Report 2015/247},
    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.