Cryptology ePrint Archive: BibTeX Citation of Report 2013/661

@misc{cryptoeprint:2013:661,
    author = {Constantinos Patsakis, Michael Clear, Paul Laird},
    title = {Private aggregation on untrusted servers with customizable thresholds},
    howpublished = {Cryptology ePrint Archive, Report 2013/661},
    year = {2013},
    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.