Improvement of Selvi et al.'s identity-based threshold signcryption scheme

Abstract

Signcryption can realize the function of encryption and signature in a reasonable logic step, which can lower computational costs and communication overheads. In 2008, Selvi et al. proposed an identity-based threshold signcryption scheme. Our previous analysis has been showed that the threshold signcryption scheme of Selvi et al. is vulnerable if the attacker can replace the group public key and has pointed out that the receiver uses the senders' public key without any verification in the unsigncrypt stage cause this attack. Further, we propose a probably secure improved scheme to correct the vulnerable and give the unforgeability and confidentiality of our improved scheme under the existing security assumption. © 2012 Springer Science+Business Media B.V.