Cryptology ePrint Archive: BibTeX Citation of Report 2015/304

@misc{cryptoeprint:2015:304,
    author = {Joshua Baron and Karim El Defrawy and Joshua Lampkins and Rafail Ostrovsky},
    title = {Communication-Optimal Proactive Secret Sharing for Dynamic Groups},
    howpublished = {Cryptology ePrint Archive, Report 2015/304},
    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.