Cloud Data Integrity Protection Mechanism Based On Blockchain

The separation of ownership and management of data results in a series of security issues in the cloud computing system,such as privacy leakage and integrity destruction of user data.On the one hand,cloud service providers may delete data rarely used by users or deliberately conceal accidental data destruction for their own reputation.On the other hand,cloud data centers may be maliciously attacked,which causes destruction and loss of sensitive data.Currently,most integrity mechanisms of cloud data use a challenge-response model for probabilistic verification and rely on trusted third-party auditors to reduce clients' computational cost and communication overhead,which increases the risk of data leakage and there is a threat of collusion between cloud service providers and third-party auditors.This thesis focuses on cloud storage data monitoring and integrity verification issues,and the specific work is as follows:(1)Mobile Agent is used to deploy the distributed model of virtual machine agent in the cloud.Virtual machine agents of multi-tenants cooperate to ensure data credible verification.The virtual machine agent mechanism not only completes reliable storage,monitoring and verification of cloud data tasks,but also is necessary to build data integrity verification mechanism based on blockchain.(2)A blockchain integrity monitoring framework is built through the model of virtual machine agent.This thesis uses the Merkle Hash Tree to generate the unique value corresponding to data,and monitor data changes with smart contract in the blockchain for sending timely warnings of data destruction to the owner.In addition,the “challenge-response” model is used to construct the scheme of cloud data integrity verification.(3)This thesis constructs and implements a prototype system of cloud data integrity protection based on blockchain,and applies the integrity monitoring scheme based on virtual machine agent and the integrity verification scheme based on blockchain.This system includes functional modules,such as the deployment of intelligent contract,cloud data monitoring and integrity verification,and protects the integrity of users' data.After security certification analysis,the mechanism can defend against three kinds of attacks by cloud service providers,and show that the mechanism has better performance comparing with existing solutions.