Research On Searchable Encryption In Cloud Computing

In recent years,as cloud computing has developed rapidly,more and more individuals and enterprises are tending to store their information into the cloud server.The usage of cloud not only eases the burden of local data management,but also makes the user enjoy the more convenient service.However,to ensure data security and user privacy,what's more,to make sure that the sensitive information will not be leaked out,the information is encrypted before stored in the server,thus in turn making searching requisite files from the vast amounts of cipher-text data much more difficult.Searchable encryption technology arises at the historic moment.It is a kind of cipher cryptography primitive which can support keyword retrieval on the cipher-text directly.With flexible use of this technology,the user can extract the files from large-scale data which would satisfy his needs.Obviously,the application of searchable encryption brings great convenience for information retrieval.Therefore,it becomes a research hotspot at present.With the usage of searchable encryption technology,there are two significant advantages.On one hand,users do not have to waste the storage space and network overhead for the unnecessary files that do not contain the keywords.On the other hand,we can make the fullest use of the powerful computation ability of cloud server for the purpose of keyword looking-up operation on cipher-text.The most important thing is that the server will not get any plaintext information.Consequently,designing an efficient and effective searchable encryption scheme plays a vital role in improving the usability of the system.After a thorough investigation into existing searchable encryption technology,we first put forward a novel ranked keyword search scheme.The scheme uses inverted list to build secure index and to achieving the purpose of ranking,it sorts the correlation between files and keywords based on relevant scores.However,the scheme has two obvious disadvantages.One is the user has to send two-roundtrip requests.The other is it only supports exact keyword search.To improve the defects of the first scheme,the paper again proposes a new symmetric searchable encryption scheme over cloud computing,which can support ranking the search results and fuzzy search.The key solutions of our scheme are as follows: first,when user inputs some keywords to retrieve,there may be some tiny mistakes and format inconsistencies.In order to solve the problem,we reasonably design the secure index and trapdoor generation algorithm to make fuzzy search possible.Second,to improve user experience degree and reduce the communication overhead and computation overhead on the client,we present a scheme that can also sort the retrieval results according to the relevancy between keyword and files under the system model.Therefore,the server can return the most relevant top-k files.Last,we demonstrate the security of our scheme,which suggests that our scheme is secure regarding to the search privacy?the one-to-many order-preserving mapping is secure and the ranking keyword retrieval is secure.Furthermore,we conduct the simulation experiment.Later,we analysis and conclude the experiment results.It shows that we significantly improve the index construction and search efficiency.