Design And Application Of Several Secure Multiparty Computing Problem Protocols

With the rapid development of information and networking technology,privacy protection has attracted extensive attention in the whole society.Privacy protection can protect the interests of the state and the individual.Frequent information leakage makes people realize that web service platforms are un-trusted.It is a challenge how to make people perform cooperative computation on their private data while preserving the privacy of the data without the help of a trusted third party.Secure multiparty computation is a key method to address this issue.Secure multiparty computation is presently a research focus in the international cryptographic community and a key technology for network privacy preserving.People can perform cooperative computation and mine the value of private datas without leaking private information.Secure multiparty has achieved fruitful results,but there are many problems need to be solved.On the one hand,many secure multiparty computation protocols are inefficient and impractical.Therefore,more efficienet and practical protocols are needed.On the other hand,many problems have not be efficiently solved.It is necessary to design efficient protocols for these unsolved problems.This dissertation focuses on the following four problems,and constructs their protocols:millionaires' problem,secure vector dominance problem,privately computing the area of the intersection of two private polygons,and privately determining whether three points are collinear.The main contents and contributions are as follows.1.The millionaires' problem is a basic building block of many secure multiparty computation protocols.In this paper,we first propose a 0-1 encoding scheme to encode private numbers,then,based on the new encoding scheme and homomorphic encryption scheme,we design a protocol for millionaires' problem and prove that the protocol is secure in the semi-honest model using the simulation paradigm.The analysis indicates that our protocol is simpler and more efficient than the existing protocols.Finally,we utilize this new protocol to construct a protocol for privacy-preserving data querying problem,and show its application example.2.Secure vector dominance problem is to compare the number relation between the corresponding components of two private vectors without leaking the components.In this paper,we first propose an encoding scheme to encode private numbers,and then,based the new encoding scheme and homomorphic encryption,we design a protocol for secure vector dominance problem and prove that the protocol is secure in the semi-honest model using the simulation paradigm.Finally,we use the scheme to solve the integer division problem and to privately determine the relation between point and lines.3.Existing protocols for secure multiparty computation of the aera of intersection of two private polygons are approximate,and there is no protocol to privately solve this problem accurately.In this study,based on Paillier's homomorphic encryption algorithm and oblivious third party,we devise a protocol to privately determine whether two private line-segments intersect.If yes,evaluate the intersection point.Then combining point inclusion protocol,we propose a protocol to privately compute the area of the intersected polygon.We prove that these protocols are secure in the semi-honest model using the simulation paradigm,analyze their performance.Finally,we demonstrate an example of their applications.4.Privately determining whether three points are collinear is a novel problem that has not been investigated.In this study,we device a protocol for the problem based on Paillier's homomorphic encryption scheme.Based on this,we further propose a protocol for privately determining the relationship of point and line-segment.Finally,we prove that these protocols are secure by using the simulation paradigm,analyze their performance,and show their applications.