Research On Off-chain Data Access Mechanism Of Smart Contract Based On Content Extraction Signcryption

Due to the limitation of blockchain storage,the requirements for storing all data on the blockchain cannot be met.The solution is to store the calculation results and key data on the blockchain and save the other data off the chain.The method can solve the problem of insufficient storage on the blockchain.However,blockchain and smart contract need to perform off-chain data exchange operation to gain data from cross-chain,sidechain or internet.In brief,blockchain and smart contract need to gain data off the chain.At present,mainstream smart contract platforms do not support direct access to off-chain data,and the methods of accessing off-chain data are more complicated,which leads to lower efficiency.At the same time,the privacy of data is also attracting more attention.Therefore,it is of great significance for the future development of blockchain and smart contract to gain off-chain data effectively,improve efficiency,and protect privacy.Therefore,this thesis studies the off-chain data access mechanism of smart contract based on content extraction signcryption.The mainly works are as follows:1)Based on content extraction signcryption,using elliptic curve encryption and certificateless design,a certificateless content extraction signcryption algorithm that supports privacy protection is proposed.Based on content extraction signcryption,it solves the problem of leakage of private data and realizes privacy protection during the sign process.Elliptic curve encryption and certificateless design are adopted to solve the problems of low signature efficiency and certificate management.Finally,the accuracy,security and efficiency of the algorithm are analyzed.The results show that the algorithm can effectively protect private data and improve signature efficiency.2)A data access framework for smart contract off-chain based on content extraction signcryption is designed.The framework includes a content provider module,an on-chain smart contract module,and a validator module.The on-chain smart contract module includes two parts: Oracle smart contract and User smart contract.The content provider module sends a message to provide off-chain data for the on-chain smart contract module and signs the message.The Oracle smart contract forwards the off-chain data and signature to user smart contract.The User smart contract receives the off-chain data,executes the signcryption extraction operation,and sends the signcryption extraction to the verifier contract.The verifier contract performs the verification operation and outputs the verification result.3)Design,implement and test the smart contract CV information access system.Combined with the Ethereum smart contract platform,a smart contract CV information access system is implemented,thereby verifying the feasibility of a smart contract off-chain data access framework based on content extraction signcryption.At the same time,the efficiency of the system was tested.The results show that the system can effectively improve the efficiency of data access outside the smart contract chain.