Design And Implementation Of Real Estate Deal Electronic Contract Depository System Based On Blockchain

Blockchain,a new paradigm of distributed computing platform,can provide trusted functions automatically such as notarization arbitration and coordination which previously relied on people or centralized centers while on protocols agreed by all parties,and can builds trust at low cost in an untrusted environment.Blockchain has been widely applied to contracts certificate,copyright,products traceability,E-government data sharing and other fields.We explore the problems that exist in housing transaction contracts deposit and certificate field,for example,contracts are liable to be tampered,difficult to be authenticated and circulated in different departments because of centralized storage.This thesis aims to solve the problems mentioned above and proposes to build the Real Estate Deal Electronic Contracts Depository System(REDECDS)based on blockchain technology that can have the benefits of contracts tamper-proof and fast reliable circulation.The thesis builds REDECDS based on Hyperledger Fabric platform.REDECDS realizes the certificate depositing,evidence collection,inquiry,verification,traceability and credible circulation functions of housing transaction contracts,mortgage loan and other contracts among real estate intermediary company,real estate transaction management bureaus,bank,tax bureau with smart contracts to improve the collaborative efficiency of the electronic contracts.The characteristics and innovations of proposed system are mainly reflected in:(1)System adopts double chain system architecture and builds a multi-center alliance chain platform among real estate intermediary companies,the real estate transaction management bureau,banks.The housing transaction contracts chain is established at the real estate transaction management bureau nodes.The mortgage loan contracts chain is established at the bank nodes.Kafka consensus is carried out among the multicenters.The cross-chain interaction between the two chains is carried out by means of relay,which realizes the automatic business process of contracts signing and identification.(2)The on-chain and off-chain storage mode is adopted.Large files,such as electronic contracts,are stored off-chain,and off-chain indexes are established for on-chain contracts data to reduce storage overhead and improve query efficiency.(3)By realizing the cross-chain association between the two chains,and establishing the associated contracts indexes,this system has the benefits of contracts traceability and fast reliable circulation.The results show that the system could realize the confirmation and management of real estate ownership,improve the reliability and security of contracts information of the housing transaction process and reduce the collaborative cost of multiple departments by testing and analyzing the functions and performance of the prototype system REDECDS.