Cryptology ePrint Archive: BibTeX Citation of Report 2012/508

@misc{cryptoeprint:2012:508,
    author = {Yi Deng and Juan Garay and San Ling and Huaxiong Wang and Moti Yung},
    title = {On Limitations of Universal Simulation: Constant-Round Public-Coin Zero-Knowledge Proofs Imply Understanding Programs},
    howpublished = {Cryptology ePrint Archive, Report 2012/508},
    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.