An Efficient SSE Scheme With Constant Client Storage Cost In The Cloud

As the product of information age,the development of cloud computing suffers from security threat.Users encrypt documents and then send to the cloud to ensure the security in the cloud server.However,encryption limits users' ability to search and update documents.Therefore,the researchers proposed searchable encryption which allows users to perform key-word search without decrypting the encrypted documents in the cloud server.We study the searchable encryption and propose an efficient scheme.Firstly,we introduce the research status of searchable encryption,and find some short-comings through the analysis.In the existing searchable encryption scheme,the client(user)has to save a state list related to the number of keywords locally.The list is used to generate search tokens during the search process and needs to occupy the local storage.In order to save the cost of client storage and not give up the original efficiency and security of the existing schemes,we design an efficient and forward secure SSE scheme with constant client storage cost.Secondly,we design a two-level structure which consists of keyword index chain and encrypted documents index chain for server storage.The design of keyword index chain can replace the local state list in the existing schemes.Therefore,we can reduce the local storage cost.Encrypted documents index chain is used to improve efficiency of search and update process,and make up for the drawback which is caused by keyword index chain structure.If we only use keyword index chain to store the encrypted documents,we have to rebuild the structure frequently due to the fast consume of the chain.Based on the two-level structure,we design an SSE scheme with constant local storage cost and analyze the security of it.In addition,the expansion of two aspects,efficiency optimization and supporting deletion,is also carried out.Finally,we make a theoretical and experimental comparison of the proposed and existing SSE schemes.The result shows that our scheme which is based on the two-level structure is forward secure and achieves efficient search and update performance both in theory and in practice.In addition,our scheme is the first SSE scheme with constant client storage cost while satisfying efficiency and forward security.