Adaptively Anonymous Public-Key Broadcast Encryption Scheme without Random Oracle

Anonymous is one of the most important security properties for kinds of Internet applications. In this paper, we consider the privacy-preserving problem in the context of public key broadcast encryption. We provide a new security definition for anonymous public key broadcast encryption, and construct a new scheme. To achieve anonymous, we blind the ciphertexts using the random factors. Moreover, we use a pair of orthogonal bases to construct secret key and ciphertexts for proper decryption. Our anonymous publickey broadcast encryption scheme can be proven in the adaptive model without random oracle. The key technique used to obtain our result is an elaborate combination of the dual system encryption proposed by Waters and a new approach on bilinear pairings using the notion of dual pairing vector spaces (DPVS) proposed by Okamoto and Takasima.