Study On Secure Multi-party Comuptation And Application Protocols

Secure multi-party computation is one of the most important areas in modern cryptography. For secure multi-party computation in distributed networks, it is essential to realize multi-party participation of secure cooperative computation. As most of the current secure protocols in network applications can be considered as certain secure multi-party computation protocols, the secure multi-party computation has attracted attention of many researchers.Current research on secure multi-party computation mainly concentrates on two aspects. One is on the fundamental theoretical research, including research on the secure model and the definition of general security, on basic protocols and general design methods of secure multi-party computation, and on analytical methods for protocol security. The major achievements include the vigorous definition of security using the semi-trust model and the malicious model, feasibility of secure protocols under various secure models, and the general design methods for secure protocols. The other aspect is on the practical application of secure protocols, including electronic auction, electronic voting, fair exchange, privacy preserving data mining, etc. As a result, large amount of secure protocols have been proposed.Besides the above mentioned accomplishments in the theoretical and practical study on secure multi-party computation, there are still many important research questions remaining to be answered. In the theoretical aspect, current secure model and definition of general security cannot reflect characteristics of different applications. A more practical secure model is needed to be investigated. Protocol design using general design methods is normally inefficient. The protocol design methods specific to certain applications are worth further investigation. In the design of practical secure protocols, current secure protocols can be improved. To deal with new problems abstracted from applications, new secure protocols need to be designed.Based on the above discussions, this thesis covers the following topics:1. Investigate practical secure model and definition of general security that consider application characteristics. 2. Investigate practical design and analysis methods for secure protocols.3. Investigate methods that improve existing secure protocols.4. Investigate new secure applications and corresponding secure protocol design.Accordingly, this dissertation has the following accomplishments:1. Regarding the practical secure model The construction of practical secure model is investigated. As a result, an application oriented secure model and definition of security is proposed which is based on the theory of secure computation of approximations, and used as the theoretical foundation to design secure protocols and analyze security.2. Regarding the design methods of practical secure protocols A design method is proposed by using private reduction and composition theorem. This method provides an efficient way to design practical secure protocols.3. Regarding improving existing secure protocols The research works is focused on fair exchange, which is considered to be important in e-commerce. Two optimized fair exchange protocols are proposed that improve the performace of original versions. In particularly, a realistic structure is proposed for non-third party fair exchange in distributed networks, which contributes to the popularization of fair exchange in various applications.4. Regarding new secure applications and corresponding security protocol design Two secure multi-party computation based protocols are proposed for price negotiation in e-commerce and tiered wireless sensor networks, respectively. This is a valuable endeavor to explore new areas using secure multi-party computation.