Abstract:

A new signcryption scheme based on the BLS short signature and Gap Diffie-Hellman groups is proposed. It is proved that the new scheme is secure against adaptively chosen ciphertext attack in the random oracle model, and its security is reduced to computational Diffie-Hellman problem. The new scheme enjoys desirable properties as follows: signature unforgeability, public verifiability and forward secrecy. The computational costs and communication overheads of the new scheme are lower than those of signcryption schemes available, and the whole operation only requires two pairing evaluations, and the data rate of signcryption can amount to 28 percents. So the new scheme can be used in environments with stringent bandwidth constraints.

Key words: short signature, public verifiability, forward secrecy