Research On Forward And Backward Secure Dynamic Symmetric Searchable Encryption Scheme In Cloud Environment

With the rapid growth of data scale,more and more people choose to outsource data to cloud service providers for storage.However,outsourcing unprocessed plaintext data to a third party is a dangerous practice that has the potential to leak sensitive data.Encrypting data and then uploading it to the cloud is an effective method to protect data security,but the disadvantage is that the expected data cannot be obtained using conventional keyword search methods.In order to solve the problem of ciphertext search,researchers proposed the concept of searchable encryption.Searchable encryption allows users to search for keywords on ciphertext,and the massive computing and storage resources of cloud servers can save users a lot of costs.Dynamic symmetric searchable encryption is based on a symmetric encryption system,which has the advantages of fast operation speed and low overhead.In addition,it supports dynamic update of data,which is very suitable for cloud data storage scenarios.Because some information leaked during the process of data dynamic update and search may cause harm to data security,researchers have proposed the concepts of forward security and backward security.This thesis conducts research on dynamic symmetric searchable encryption,the main work is as follows:(1)Aiming at the problem that the existing schemes cannot make full use of the advantages of computer multi-core CPU parallel computing,this thesis proposes an efficient forward and backward secure dynamic symmetric searchable encryption scheme DSSE-FB1 that supports parallel search.This scheme designs a two-level index structure composed of a keyword index chain and a document index chain.The keyword index chain is similar to a one-way linked list,and the information of the previous node will be hidden in the node,thus achieving forward security.The document index chain is associated with the node in the keyword index chain,and stores the document information contained in an update operation.Through this index structure,we can realize parallel search and greatly improve search efficiency.In addition,this scheme utilizes tag value matching to logically delete documents,thereby achieving backward security.(2)Aiming at the problem that the scheme of caching search results cannot support the multiplexing of search trapdoor,this thesis proposes an efficient forward and backward secure dynamic symmetric searchable encryption scheme DSSE-FB2 that supports search result caching and search trapdoor multiplexing.This scheme designs a two-level index structure consisting of an update chain and a search chain.We can use the update chain to store the updated document information since the last search,and cache the search results after a search.By using the search chain,we can find the cached search results sequentially,which greatly speeds up the search,and realizes search trapdoor multiplexing and forward security.In addition,the backward security implementation of this scheme is the same as that of DSSE-FB1 scheme.(3)We conducted a detailed theoretical and experimental analysis of the DSSEFB1 and DSSE-FB2 schemes.The results show that compared with other similar schemes,the two schemes proposed in this thesis have obvious advantages in search efficiency and search trapdoor multiplexing.