Research On Game Model Of Secret Exchange And Its Application

With the rapid development of cloud computing and big data technology, frequent data communication and sharing among players result in the widespread application of distributed computing. However, due to the openness and resource sharing of such platform, the data exchange between players is confronted with a lot of security challenges. Traditional secret exchange has exposed some inherent defect without considering action motive of players, such as not prevent cheating. Game model of secret exchange belongs to the field of cryptography and game theory, all players are seen as rational, they decide whether to comply with protocol based on utility function, which can be better to solve the security of protocol.We study the development of the secret exchange, discuss the security and the problems of existing rational secret exchange protocols. Analyzing the strategies and the utility of player, we construct game model of player cooperation, resisting coalition and fair two-party computation, and then apply these models to protocols design. To motivate all players to comply with the protocol, we control utility function by penalty strategy. Therefore, although each player tends to be the only one of having the secret, they are willing to comply with the protocol for their own interests. The main contributions of this dissertation are as follows:(1) Focusing on player cheating only can be found, not be stopped in traditional secret sharing protocol, we construct game model of player cooperation based on trigger strategy. The function and penalty strategies are combined, and her utility function will reduce if a player deviates from the protocol. As rational players hope to get the final secret, they will choose to cooperate, and then the goal of preventing cheating is achieved.(2) Concentrating on the common problem of player conspiracy in secret sharing, we set up game model of preventing player conspiracy based on the reputation. The conspiracy motives and action of rational player in detail is analyzed, the utility function will increase the negligible value if a player conspires with others through parameter settings. At the same time, the players deviating from the protocol by reputation mechanism will be punished. This model can achieve computable Nash equilibrium, which ensures the rational players have motivation to comply with the protocol.(3) In order to solve the fairness problem of traditional two-party computation protocol, we adopt the ideal and real game model of fair two-party computation based on incentive-compatible mechanism. According to the fair definition of the model, we give the protocol of rational secure two-party computation to guarantee that players to send correct data is the dominant strategy and the two player can get results fairly by controlling the strategy and utility function. Finally, we prove the protocol can achieve ideal functions and analyze the Nash equilibrium.(4) Apply these models to the secret exchange protocols. For players, cooperation motive rational secret sharing protocol, resist conspiracy rational secret sharing protocol and rational secure two-party computation protocol with fairness are proposed. Further, it is the first time that rational player idea is introduced to the threshold signature, i.e., according to the dealer distributing wrong sub-key and the signature uncooperative behavior, we design a rational threshold signature protocol. Regarding signature as rational players’ right and taking their responsibility simultaneously, we use bargaining model to solve rational signatures key distribution, and build rational synthesis mechanism adopting random uniform grouping. This method can ensure each player can get the correct sub-key and have the motivation to complete the message signature.