Research And Implementation Of Blockchain-based Smart Contracts

As the underlying technology of cryptocurrency,blockchain technology has attracted much attention as Bitcoin has become active in the technology and financial communities.Its qualities such as decentralized,transparent,credible,and tamper-resistant also provide a reliable execution environment for smart contracts and ensure the fair and equitable implementation of smart contracts.Based on blockchain technology,Ethereum provides a complete solution to smart contracts,so that the application of blockchain has been extended.In recent years,many industry alliances have succeeded in applying Consortium blockchain to solve the decentralized problem,making it the first choice for enterprise-level applications.Since the transactions in the blockchain are stored in the global ledger,the entire life cycle of the smart contract is broadcast across the network and recorded,which makes the privacy of the contract cannot be guaranteed.Simultaneously,Ethereum still uses the proof-of-work to achieve data consistency,but this consensus mechanism does not apply to the Consortium blockchain environment.In view of the above problems,the research in this thesis is on the basis of the Ethereum Consortium blockchain.In this thesis,a smart contract model based on blind signature technology is proposed via studying the blockchain related technology,smart contract technology and cryptographic technology involved.The proposed model incorporates the partially blind signature with designated verifier algorithm.The algorithm's limited verifiability,non-repudiation and partial blindness guarantee the privacy of the smart contract.Meanwhile,aiming at problems of proof-of-work mechanism such as inefficiency and waste of hash,this thesis uses PBFT and improves it to form an improved practical Byzantine fault tolerance algorithm which is more suitable for the Consortium blockchain scenario.Finally,this thesis builds a simple decentralized equity transfer system based on the proposed model,which implements its transaction-related operations through smart contracts in the blockchain.