Efficient signcryption between TPKC and IDPKC and its multi-receiver construction

The primitive signcryption provides authenticity and privacy simultaneously. In this paper, we present efficient signcryption schemes between the traditional public key cryptosystem (TPKC) and the identity based cryptosystem (IDPKC). In contrast, all the existing signcryption schemes available in the literature, to our knowledge, are limited to within one type of cryptosystem. We also discuss them in the multi-receiver setting. Formal security proofs are provided to guarantee the security for our schemes, in the random oracle model, under the hardness of the bilinear Diffie-Hellman problem.