Privacy-preserving information aggregation and authentication in distributed and mobile networks

Abstract

The development of computer system and network enabled us to use lots of useful applications in the field of information technology. As the exchange of information increases, the protection of the privacy becomes essential issue in information aggregation and sharing. Among the technology of the information security, this study attempted to seek a solution on the subject of secure data collection in distributed and mobile environments, and on the subject of method of effective authentication between multiple users. The goal of this thesis is to investigate privacy preserving methods in distributed and mobile networks. At first, we study on privacy-preserving information aggregation and sharing in distributed networks. Recently lots of privacy preserving set operations are proposed. When one set operation does not reveal any other elements except for the elements in the resulting set, it is said to be privacy-preserving set operation. Most of privacy preserving set operations is designed using polynomial representation of user`s private set. In this study we develop a polynomial operation algorithm on encrypted polynomials for getting fast implementation of privacy-preserving set operation based on the polynomial representation. We propose novel polynomial arithmetic algorithms of multiplication, expansion, and evaluation of encrypted polynomial using Karatsuba and divide-and-conquer methods. As the result of our proposed algorithms, the complexity of the set operation can be reduced from original O(k2) to O(klog2 3), where the k is the cardinality of user`s private set. We also study on the issue of finding most frequent top-k elements from multiparty information aggregation. Earlier researches on this issue failed to provide provable security since the rigorous security goals and adverarial model are not defined. In this study, we apply the provably-secure concepts to Privacy Preserving Top-k (PPT-k) protocols at first time. We also defined a new security notio...