Some Applications of Signcryption Schemes to Distributed Protocols

It is shown in this paper that a kind of new cryptographic primitive proposed by Zheng in 1997, Signcryption, may be applied to construct distributed cryptographic protocols. In fact, the protocols based on Signcryption have the following two properties: Each message exchanged between two participants can be transferred in short data packet, and messages that carry key materials are unforgeable and non-repudiatable without the involvement of a trusted key distribution center. Firstly, based on the modified signcryption scheme of Zheng and Verifiable Secret Sharing(VSS) idea, this paper gives a kind of threshold signcryption scheme without any trusted center for the first time. Furthermore, this scheme can gain its ends of both threshold signature and threshold encryption simultaneously and the costs is much cheaper. In addition, non-repudiation is also offered. Secondly, by analyzing recent distributed key generation protocols, especially Naor’s idea, it put forward a new protocol mainly based on signcryption, called SC-DKDS. Compared with others, SC-DKDS does not need any additional costs, such as authentication channels, private channels or any complicated zero knowledge proofs. The security proofs of the protocols mentioned above are given in RO(Random Oracle) model.