Secure Multi-receiver Communications: Models, Proofs, and Implementation

With the demand of providing message authentication and confidentiality as well as receiver anonymity in applications such as multicast communication, digital content distribution systems, and pay-per-view channels, many anonymous multi-receiver signcryption mechanisms have been put forward to offer these functions efficiently, which have the lower computational cost and communication overhead compared with the signature-then-encryption approaches. However, most certificateless-based schemes either focus on providing receiver anonymity or focus on improving signcryption efficiency. In addition, most certificateless-based schemes rely on bilinear pairing operations, which are more time consuming than modular exponentiation and scalar multiplication in finite fields. In this paper, we propose a practical anonymous multi-receiver certificateless signcryption (AMCLS) scheme that can satisfy message confidentiality, source authentication, and anonymity simultaneously and efficiently. In the proposed scheme, the sender’s signcryption cost increases linearly with the increase of the designated receivers, while the unsigncryption cost per receiver is constant. The adoption of elliptic curve scalar multiplication instead of bilinear pairing operation improves the efficiency of the proposed scheme. Both the sender and receivers’ identities are encrypted from being exposed to offer anonymity. Through security analysis, our proposal can be proved to achieve chosen-ciphertext attack (CCA) security in encryption indistinguishability and receiver anonymity in strong, commonly accepted attack models. Theoretical analyses and experimental results demonstrate that our scheme enjoys a better efficiency than other certificateless-based schemes.