Cheng-Kang Chu Jian Weng Sherman S. M. Chow Jianying Zhou Robert H. Deng Conditional Proxy Broadcast Re-Encryption. 327-342 2009 ACISP http://dx.doi.org/10.1007/978-3-642-02620-1_23 conf/acisp/2009 db/conf/acisp/acisp2009.html#ChuWCZD09