A Method Of Identifying Cheaters In Secret Sharing Schemes Based On Signcryption

For a general secret sharing scheme,there are two problems:(1) An attack from the attackers:when the Dealer release the share,how can the participants verify the authenticity of the shares they have received? How to confirm the shares from the Dealer not juggled by an attacker?(2) The honesty of the participants:how can a participant verify the authenticity of the share released by another participant? Should there be a malice who offers a fake share,how can a participant identify it during reconstructing the secret?Signcryption,which was first proposed by Zheng in CRYPTO97,simultaneously fulfills both the functions of digital signature and encryption in a logical single step.It needs a lower cost than the traditional signature-then-encryption approach.Zheng introduced two material signcryption schemes SCS1 and SCS2,which don't satisfy public verifiability and forward security.It is a public problem to design a signcryption scheme satisfying public verifiability and forward security simultaneously.The main contributions of the paper are:The signcryption SCS2 proposed by Zheng is improved to satisfy public verifiability and forward security simultaneously.And its security is the same as that of the original scheme.A new method of identifying cheaters in secret sharing schemes is proposed based on the improved SCS2.With the method,a private channel is not necessary between the Dealer and each participant,and anyone can verify the authenticity of the share released by any participant during reconstructing the secret.