Research On Some Problems Of Secure Multi-party Computation

With the rapid development of Network Technology,there are more and more people obtaining information and communicating with each other through the Internet frequently.However,network is different from the reality,such as network information may be false,what is more,someone may steal other people's private information in the network for another.The problem of Secure Multi-party Computation(SMC)is the problem of cooperative computation which could occur among mutually distrusted participants without leaking the privacy of parties.This thesis mainly studied four aspects.Firstly,this thesis introduces the research background and meaning of Secure Multi-party Computation.It also describes the basic knowledge and introduces protocols which have been proposed such as secret comparison,homomorphic encryption,and distance measurement.Secondly,this thesis proposed a new secure sum protocol based on public key encryption.This protocol used public key encryption technology and random algorithm.This protocol can improves safety and reduces communication complexity.In addition to,this thesis analysised the correctness and security through discussion.In order to facilitate comparison,this thesis defined the level of coalition-proof.Thirdly,this thesis proposed a new point-line distance protocol based on sharing a secret and a determination protocol of point-line position relation.The new point-line distance protocol used new mechanism and improved the efficiency compared to the protocol at present.Then,this thesis validated its efficiency and fairness through the theoretical analysis and mathematical experiment.Fourthly,this thesis improved the privacy-preserving closest pair protocol based on distance.The protocol can rule out most pairs that can't be the closest pair through protocol mechanism and reduce the number of user's communication and the computing cost.In addition,this thesis randomly selected a certain number of points and simulated the process of protocol.At last this thesis proved the efficiency of the protocol through experiment.At the end,we made a summarization and pointed out the next research direction.