Cryptology ePrint Archive: BibTeX Citation of Report 2012/215

@misc{cryptoeprint:2012:215,
    author = {Rosario Gennaro and Craig Gentry and Bryan Parno and Mariana Raykova},
    title = {Quadratic Span Programs and Succinct NIZKs without PCPs},
    howpublished = {Cryptology ePrint Archive, Report 2012/215},
    year = {2012},
    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.