Research On Key Technologies Of The Dynamic Searchable Encryption In Cloud Environment

With the continuous development of science and technology,cloud computing,as a large resource pool facility,has rapidly entered people's life.More and more individuals or enterprises choose to outsource their data to the cloud server,so as to save personal or enterprise management cost and storage overhead.However,while cloud computing provides convenience for individuals or enterprises,it also brings some data privacy and security issues.Therefore,in order to protect user data privacy,data is generally encrypted before being stored on the cloud server.This can prevent unauthorized access to user data by the cloud server or malicious third parties.However,this also makes it impossible for users to directly perform keyword search and retrieval on encrypted data.Therefore,Searchable Encryption(SE)came into being,which allows users to search and retrieve encrypted data stored on cloud servers without exposing the content of the data.Therefore,it has very important research significance and value.However,the existing research results are still insufficient in terms of safety,efficiency and function.On the one hand,in the existing searchable encryption schemes that guarantee forward and backward privacy,most of them only achieve singlekeyword query,did not achieve multi-keyword query.On the other hand,in most SE scenarios,the cloud server is assumed to be an "honest" model,that is,the cloud server will strictly execute the algorithm content,but in reality,the cloud server is likely to perform only part of the protocol computation task and return incorrect computation results in order to reduce the computational cost.However,the general SE schemes lack the verifiability of the results returned by the cloud server.To solve the above problems,this thesis makes in-depth research on searchable encryption based on the cloud,and proposes two SE schemes:(1)A multi-keyword searchable encryption scheme to ensure forward and backward privacy.Under the premise of ensuring forward privacy and weak backward privacy,this scheme realizes multi-keyword query and retrieval.At the same time,the program does not need to pre-define a keyword dictionary,and new keywords can be added at any time during the execution of the program.The safety analysis and performance comparison analysis show that the scheme can have certain advantages in performance under the premise of ensuring safety.(2)A multi-keyword searchable encryption scheme for verifiability.This solution proposes a searchable encryption solution with verifiable query results for the "dishonest" cloud server model,so that it has more complete functions while meeting security,and does not need to store a local copy of the outsourced data.At the same time,the solution realizes the attribute query of numeric type and text type.Finally,through the comparison of simulation experiments,it is proved that the scheme has moderate computational and storage costs.