| Data transactions can promote the flow of data between different fields and make data play a greater role.Centralized trading platforms have the risk of single point of failure,while the emergence of blockchain,with its decentralized characteristics,has largely reduced the risk of single point of failure of data trading platforms,but there are still many problems in data trading.The first is how huge amounts of data can be securely stored on blockchain;The second is the security of the transaction process,how to ensure that the two parties will not deny the fact of the transaction and disclose privacy,and ensure that search data securely;Finally,the problem of access control of data commodities,how to authorize and revoke access control permissions.In order to solve the above problems,we proposes a data transaction security scheme,the main contributions are:1)Design and implement a secure data trading system based on blockchain SDES.By adopting IPFS distributed storage platform and designing storage adaptation layer,the system converts the external heterogeneous storage data to be traded into a unified IPFS hash value transaction form,which solves the problem of massive data security storage and the limited capacity of blockchain.IPFS and blockchain are combined to construct a secure and effective off-chain storage.The transaction record is saved on the blockchain by the non-tampering feature of the blockchain,which effectively solves the problem that the data transaction party denies the transaction fact.2)Aiming at the problem of how to query data efficiently and safely without leaking privacy,we proposes a dynamic searchable scheme based on blockchain,which improves the dynamic searchable encryption algorithm,improves the dual index structure to the one-to-many storage form of keywords and file sets,and combines IPFS to realize the purpose of query and update files safely and quickly3)Aiming at the access control problem of transaction data,based on SDES business,CPABE attribute encryption method is adopted to make fine-grained authorization based on user’s identity attribute label.In order to realize the function of automatic authorization revocation,CP-ABE attribute encryption method is improved,and a scheme of permission revocation based on time period is proposed.By designing the key of authorization period and user attribute key,the user can automatically revoke the permission according to the time period.4)Based on the Ethereum blockchain,we implemented the SDES system,and verified the security and advantages of the system through experimental comparative analysis and security analysis;At the same time,it is verified that the dynamic searchable encryption scheme based on blockchain has faster query efficiency and file update efficiency,and the access control scheme based on CP-ABE can correctly realize the function of encryption and decryption according to the time limit,and has good encryption and decryption efficiency. |
