Certificateless Broadcast Signcryption with Forward Secrecy

Certificate less cryptography achieves the best of the two worlds: it inherits from identity-based techniques a solution to the certificate management problem in public-key encryption, whilst removing the secret key escrow functionality inherent to the identity-based setting. Broadcast signcryption, which enables the broadcaster to simultaneously encrypt and sign the content meant for a specific set of users in a single logical step, provides the most efficient solution to this dual problem of confidentiality and authentication. In this paper, we first construct a certificate less broadcast signcryption scheme and show that the proposed scheme is secure against an uncertified user and a malicious trusted authority simultaneously under the Diffie-Hellman assumptions in the random oracle. Moreover, our scheme satisfies register authentication and forward secrecy security attributes. As compared with the recently proposed broadcast signcryption schemes, our scheme has better performance in term of the security and computation overheads.