MIDSCYK: An efficient provably secure multi-recipient identity-based signcryption scheme

Signcryption is a public key cryptographic primitive that combines the functionalities of encryption and digital signatures in a single logical step at low computational and communications costs. This paper presents a new efficient multi-recipient identity-based signcryption scheme. The scheme provides public verifiability of ciphertext origin which is an essential requirement in firewall authentication protocols. The scheme offers considerable reductions in both the computational overhead and bandwidth requirements compared to other schemes in literature. The scheme is provably secure against chosen ciphertext attacks in the random oracle model under the assumption of the hardness of the decisional bilinear Diffie-Hellman problem. Moreover, the scheme is existentially unforgeable and thus supports some sort of non-repudiation. The performance enhancements offered by the proposed scheme promote its use in several applications such as authenticated mail transfers among large mailing groups as well as virtual conference scenarios.