Anonymous Multi-receiver Certificate-Based Encryption

In a multi-receiver encryption environment, a sender can randomly choose a set of authorized receivers while distributing messages to them efficiently and securely. Recently, more and more researchers concern the privacy of receivers. They mentioned that an authorized receiver does not want other entities, except the service provider, to be able to derive her/his identity in many applications such as pay-TV. However, most of these protocols either provide no formal security proofs or are inefficient owing to high computation cost. In this paper, we construct a provably secure and efficient anonymous multi-receiver certificated-based encryption scheme, PMCE, which avoids the key escrow problem while preserving the implicit certification of identity-based setting. The proposed PMCE gets rid of pairing computation to encrypt a message and only needs one pairing computation to decrypt the cipher text. Finally, we define the security models and offer formal proofs to all properties including receiver anonymity.