Research Of Secure Multi-Party Ranking Problem

Along with the continuous development of network technique, and with the appearance of high quality computer and net grid, the meanings and mode of computations are mostly changed. All of this makes it easy that the users can make use of the powerful computation resources. In such circumstance, The safety of users' data become very important and necessary's secure Multi-Party Computation comes forth. Secure Multi-Party Computation was Firstly brought forward by A.C.Yao in 1982: There are n participants P₁,P₂,...,P_n, who want safely compute a function together. And the word safe means that the correctness of output message and the secrecy of input and output message. Concretely, each participant P_i has his secret input message x_i, and all the n participants compute a function together: f(x₁,x₂,...,x_n), when computation has been finished, each P_i knows only value of f(x₁, x₂,...,x_n) ,but not other information.Secure Multi-Party Computation protocol is an important area in cryptography. It's the basis of many distributed cryptographic protocols, such as threshold cryptosystem, electronic voting and electronic auction etc. It is based on many basic cryptographic protocols (e.g.homomorphic encryption and zeroknownedge proof) and some basic protocols in distributed computation (e.g. obvious transfer and broadcast protocol).Research in the SMC area has been focusing on privacy-preserving scientific computations, privacy-preserving geometric computations, privacy-preserving data mining, privacy-preserving statistical analysis etc.To sum up, the innovations of this thesis could be summarized as following: 1,We summarize theory,techinique and actuality of SMC,and propose SMMR(Secure Multi-party multi-data Ranking)problem.We give a model about SMMR problem to describe it.2,We propose a protocol based on RSA homomorphic encryption and OT protocol to solve SMMR problem. This protocol satisfy security and fairness comparing using Yao's protocol repeatedly.3,We propose a protocol based on large number factorization to solve SMMR problem. This protocol not only satisfy security and fairness, but also don't use any encryption, it has better efficiency.