Identity-Based Multi-Signcryption Scheme without Random Oracles

Signcryption is a very important technology in message security and the sender's identity authentication for communication in the open channel.To adapt multi-user settings,this paper defines the formal model of identity-based multi-signcryption scheme and proposes the first identity-based multi-signcryption scheme without random oracles based on Waters' identity-based encryption scheme.The scheme is proved secure against adaptive chosen ciphertext attacks and adaptive chosen message attacks under decisional bilinear Diffie-Hellman assumption and computational Diffie-Hellman assumption respectively.