Research On Several Key Technologies Of Rational Threshold Signature

In this fast developing net age, the information society has been going through anunprecedented revolution triggered by rich online resources and its coexisting sharingattribute. In the process of communication, how to protect information security is animportant proposition as information theft, leak and fraud turned out to be seriousproblems. The basis of information security is cryptology. As the public keycryptography been raised, according to the famous kerckhoff hypothesis theconcentration of study was transferred from cryptographic algorithm security to secretkey protection.Threshold secret sharing is an ideal way to implement multiparty secret sharing.By dividing the original secret into several sub-secrets, the possibility of leaking thesecret is dramatically decreased. By further study of the scholars, there already existsa bunch of secret sharing schemes. In the aspect of realizing the scheme, secretsharing has been combined with many other subjects such as quantum, graphics andCommunications et al.In the light of existing schemes, we analyzed the collusion phenomenon inrational secret sharing, studied the status of recent research. A rational secret sharingagainst collusion has been raised by combining the cooperative game. The scheme canbreak the payoff distribution proportion so that conspirators will not be able to obtainany more payoffs. The collusion will be destroyed. Using the payoff theory in Nashequilibrium, the scheme ensures that the payoff of deviation is minimized. Finally, ourscheme is proved to be Nash equilibrium.In the field of threshold signature, in order to prevent mobile attack, forwardsecure has been raised. But most signature schemes with forward secure feature aredesigned in random oracle model. They adopt the hypothesis design in security proofphase, so that they are not the strict provable secure. In order to solve this, a newthreshold signature is raised in standard model with forward secure. Dynamic secretkey updating technology is conceived so that the signing is simplified as well as thepublic key revocation. All signers are able to update their partial key and publiclyverify others’. Due this scheme is designed in standard model, so it has a wider realsignificance.Constructing a rational threshold signature has a crucial meaning. It can resolvethe problem of participants competing for resources and access rights. Through deepstudy of threshold signature and game theory, we gave the feasibility analysis andapplication prospects of rational threshold signature. By combining the game treestructure based on expanded description of game with hierarchical key structure, we raised a new rational threshold signature. The scheme is based on mix strategy ingame theory, defines the condition for signers not deviating. Its secure is based onmath problems that cannot be solved in polynomial Time. It is proved to be a sub-game perfect Nash equilibrium.At last, a new identity-based rational threshold blind signature is raised. It aimsat adapting game model into blind signature which has a wide range application in e-business and e-government. We think punishment stretagy is so strict that sometimesit leads low game efficiency so an encouraging strategy is designed to prevent this. Bydetailed analysis of partial signature reconstruction, the conditions of following thegame for each player and their corresponding utitlity are presented to prove that thescheme is Nash equilibrium of repeated games.