A Security on Multi Keyword Search over Outsourced Cloud Data Using N-Gram

Abstract

In recent years, Cloud computing is gaining much momentum in the IT industry which can be used to organize various resources of computing, storage and applications. Many IT enterprises and individuals are outsourcing their databases to cloud server. Variety of users can access and share information stored in the cloud independent of locations. The outsourced data may contain very sensitive information such as e-mails, company financial data, government documents, Personal Health Care records, facebook photos and business documents.We define and solve the challenging problem of privacy-preserving multi-keyword ranked search over encrypted data in cloud computing (MRSE). We establish a set of strict privacy requirements for such a secure cloud data utilization system. Among various multi-keyword semantics, we choose the efficient similarity measure of “coordinate matching,” i.e., as many matches as possible, to capture the relevance of data documents to the search query. We further use “inner product similarity” to quantitatively evaluate such similarity measure. We first propose a basic idea for the MRSE based on secure inner product computation, and then give two significantly improved MRSE schemes to achieve various stringent requirements in two different threat models. To improve search experience of the data search service, we further extend these two schemes to support more search semantics with N- gram Features.