Anonymous and provably secure certificateless multireceiver encryption without bilinear pairing

Recently, numerous multireceiver identity-based encryption or identity-based broadcast encryption schemes have been introduced with bilinear pairing and probabilistic map-to-point MTP function. As the bilinear pairing and MTP functions are expensive operations, any cryptographic schemes based on these operations experience high computational burden. The certificateless public key cryptography sidesteps the private key escrow problem occurring in identity-based cryptosystem and certificate management troubles of certificate authority-based public key cryptography CA-PKC. We observed that certificateless multireceiver encryption CL-MRE scheme without pairing and MTP hash function has not yet been considered in the literature. In this paper, we proposed a bilinear pairing and MTP hash-function-free CL-MRE scheme with chosen ciphertext attack resilience. The detailed analyses provide evidence that our scheme achieves forward secrecy, backward secrecy, and low computation costs than others. The scheme also provides confidentiality of the message and receiver anonymity in the random oracle model with the hardness of computational Diffie-Hellman problem.