Rational computing protocol based on fuzzy theory

Secure multi-party computing (SMPC) is often used to solve security problems in cloud computing. Rational SMPC is a kind of SMPC in the presence of rational parties, who wish to maximize their utilities. Previous works about rational SMPC only studied the security properties under complete information scenario, where parties' types are common knowledge. However, parties in practical applications have private types, which is unknown to others. This scenario is called incomplete information. In this paper, rational parties are allowed to have private types, which affect their utilities. Previously, rational parties obtain expected utilities due to unknown private types under incomplete information scenario. However, rational parties prefer to obtain pure utilities in actual life. To solve this contradiction, we use fuzzy theory to confirm the private type of his opponent; then they execute the protocol as if they know the private types just like the execution under complete information scenario. Consequently, they obtain pure utilities other than expected utility. In addition, our protocol can reduce round complexity than previous ones. Consequently, it will improve the security level and efficiency of cloud computing.