Research On Threshold Signcryption Scheme

Threshold signcryption scheme in real life has a wide range of applications, such as electronic voting, electronic auctions. Threshold signcryption scheme mainly considers two issues: One is the efficiency of the scheme. The other is the deception of sharers and distributors. According to the existing threshold signcryption schemes about these two issues, this paper designs three new schemes.First, in order to resolve the problem of low efficiency of the existing threshold signcryption schemes, an ID-based threshold signcryption scheme is proposed. Comparing with the existing schemes, this scheme can effectively reduce the information exchanges between signcryption group members, especially in the case of the group has a lot of members. This paper builds and analyses the security model of the scheme, proves security, unforgeability and robustness under adaptive chosen ciphertext attack.Secondly, the paper analysis a practical group-oriented threshold signcryption scheme, which can not resist the forgery attack of sharers and distributor. This paper, based on the original scheme, proposes a new group-oriented threshold signcryption scheme. The new scheme applies to the case that sender and receiver are a number of individuals. The new scheme is ID-based scheme. while it maintains the original scheme the features of good usability, it overcomes the security risks.Thridly, in order to achieve the public verifiability of information, this paper uses independent inspection methods, combines threshold scheme with signcryption scheme to solve the problem of publicly verifiable of confidential information. This paper firstly improves the Asmuth-Bloom threshold scheme to verifiable threshold signcryption scheme, then extends it to the verifiable secret sharing scheme, finally, combineing the threshold scheme with the signcryption scheme, structures a new threshold signcryption scheme, which information is verifiable.