IBASC: Identity based aggregate signcryption scheme with public verifiability

Signcryption is a new cryptographic primitive which performs signature and encryption in a logical operation. In many-to-one communication, sender nodes could signcrypt the transmitted massages to guarantee the authenticity and confidentiality, while the recipient node has to verify for several times. Aggregate signcryption could provide the batch verification as well as shortened message, which reduces both of the communication and computational overheads. A new identity based aggregate signcryption scheme is proposed in this paper. The receiver recovers the entire transmitted message by an unsigncrytpion operation. The ciphertext could be verified publicly. The proposal contains only n+3 bilinear pairing operations and n scalar point multiplication operations in the stage of aggregate unsigncryption. Compared with the existed schemes, the overheads of ciphertext can be reduced up to 50% at most. It is proved to be achieved IND-IBASC-CCA2 and EUF-IBASC-CMA security in the random oracle model.