Cryptology ePrint Archive: BibTeX Citation of Report 2009/142

@misc{cryptoeprint:2009:142,
    author = {Ronald Cramer and Dennis Hofheinz and Eike Kiltz},
    title = {Chosen-ciphertext Secure Encryption from Hard Algebraic Set Systems},
    howpublished = {Cryptology ePrint Archive, Report 2009/142},
    year = {2009},
    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.