Research On Data Privacy Protection Technology Based On Blockchain

With the continuous development of network technology and encryption technology,blockchain technology has been paid more and more attention in more and more fields.These fields contain a large amount of private data,such as user identity privacy data and transaction privacy data,so the majority of users take great care to protect data privacy when using blockchain technology.For existing schemes to protect the privacy of user’s identity data in a blockchain,most of them store the document data information on the blockchain.However,the blockchain has the characteristic of non-tamperability,which makes it more difficult to modify the system at a later stage and also causes a large consumption of storage space.For the existing blockchain transaction data privacy protection solutions,there are many literature studies on the privacy protection technology for both parties to the transaction and the audit and supervision technology for transaction data,but there is no solution design that simultaneously realizes the above functions.In response to the above problems,this thesis conducts in-depth research on the privacy protection of user identity data and transaction data privacy protection technology in the blockchain.The main work is as follows:(1)In order to solve the problem that the data is directly stored on the blockchain which makes it difficult to modify later,a blockchain privacy protection scheme is proposed that combines the fuzzy keyword searchable encryption technology and the homomorphic encryption technology to realize the blockchain privacy protection scheme.By introducing an intermediate node to receive the split key and using a homomorphic encryption algorithm,the security of the encryption key is protected.Five entity parts are designed in this scheme,mainly including four working stages,namely the content encryption phase,the search phase,the user access to the encrypted document phase,and the user decryption phase.In the theoretical analysis section of the scheme,the privacy protection capabilities are analyzed to verify that the scheme can achieve privacy protection for users,followed by an analysis to verify the correctness,security,and reliability of the scheme,as well as an analysis of the main functions implemented by the smart contract in the scheme.(2)In order to meet the demand for privacy protection and regulatory auditing of transaction data information in a blockchain,a privacy protection scheme using linkable group signature technology to achieve an audit trail of blockchain transaction data is proposed.Privacy protection for the sender of the transaction is achieved through the use of linkable group signature techniques,privacy protection for the recipient of the transaction is achieved through the use of improved one-time stealth address techniques,and audit trail functionality for the amount of the transaction is achieved through the use of FO commitments and interval range proof techniques in zero-knowledge proofs.Five entity components are designed in this scheme.The scheme’s specific implementation process consists of four phases,namely the initialization phase,the linkable group signature phase,the audit phase,and the traceability phase.The scheme is then analyzed for security,privacy protection capabilities,linkability,and traceability to verify the feasibility of the scheme.In addition,the comparison of this scheme with other schemes proves that this scheme has a relatively complete realization of the privacy protection and audit trail functions of transaction data.(3)The time efficiency of the scheme in this thesis can be measured by experiments.The experimental data is sourced from real data sets on the web and processed.By analyzing the experimental results,it is found that the proposed scheme has low time overhead and high data privacy protection,thus ensuring the security of blockchain data privacy protection.