Research On Privacy Protection Technology Of Outsourcing Data Based On Blockchain

With the rapid development of the Internet of vehicles,mobile Internet,and other technologies,data in various applications also presents characteristics of high growth,multiple styles,and large scale.Due to the advantages of on-demand access and low cost,cloud storage has attracted more users to outsource their data to the cloud server for storage.However,cloud storage mode of data from the user’s physical control,led to outsourcing frequent events such as leakage or loss of data.To ensure the security of outsourced data,users need to encrypt the data before uploading it,but this also prevents data sharing among users.Therefore,under the condition of ensuring the security and privacy protection of cloud storage data,how to give full play to the use value of outsourcing data is an urgent problem to be explored at present.In the research of data integrity,the traditional integrity audit scheme has the problem of untrustworthy third-party auditors(TPA).With the emergence of blockchain,the security of stored data is guaranteed due to its immutable and publicly verified nature.The integrity audit scheme of blockchain has achieved the purpose of removing TPAs,but there is still the on-chain cost of executing contracts.In the research of ciphertext search,the introduction of blockchain effectively solves the centralization problem of cloud servers in the traditional ciphertext search scheme,but there are still problems of maintaining complex index structure and on-chain overhead.At the same time,homomorphic encryption schemes are not practical in real life because of their high computational cost.A secure Trusted execution environment(TEE)in SGX(Software Guard Extensions)provides significant advantages in data sharing and computing.From the perspective of users’ actual needs,this thesis adopts the on-chain and off-chain combination method to research the above issues.The main research work is as follows:(1)Aiming at the problems of TPA untrustworthiness and on-chain overhead,this thesis designs an outsourcing data integrity audit scheme based on blockchain and TEE.First,the scheme uses homomorphic hash functions to generate data block labels for integrity verification.Secondly,this scheme combines blockchain with a trusted execution environment.On the premise of ensuring the security of outsourced data,it uses blockchain instead of TPA to complete data integrity audit operations for users in the trusted execution environment.Finally,the security analysis and experimental test show that the scheme solves the problems of TPA untrustworthiness and on-chain overhead under the guarantee of user data security,and reduces the total computing overhead of the scheme to a certain extent.(2)Aiming at the problems of complex index structure to be maintained,on-chain overhead,and poor practicality,this thesis designs a multi-user ciphertext search scheme based on blockchain and TEE.First,the scheme uses blockchain and a trusted execution environment to protect the privacy of keywords and data.Users do not need to generate indexes or keywords in advance and complete the decryption of ciphertext data and keyword search operations in the trusted execution environment.Secondly,to apply to multi-user scenarios,the scheme also designed intelligent contracts to verify user authorization requests and manage authorized users.Finally,the security analysis and experimental test show that this scheme can solve the problems of complex index structure,on-chain cost,and poor practicability under the guarantee of user data security,and can effectively meet the actual demand.