| The emergence of cloud computing has brought great convenience to data storage.More and more users choose to store data on the cloud platform,but the ownership and management rights of data stored on the cloud platform are separated,and cloud computing has virtualization,multi-tenancy,on-demand delivery and other characteristics,which will bring a series of security problems,such as data leakage.At present,the deterministic deletion mechanism of data in cloud storage scenarios is a matter of great concern,and how to safely delete data and prevent data leakage is an urgent problem to be solved.Most of the existing solutions are to convert the problem of deterministic deletion of data into the problem of deletion of the corresponding encryption key.However,the existing deletion mechanism is not perfect in ensuring the security of outsourced data storage and the completeness of data deletion.There are problems such as data sharing easily leaking privacy,data deletion is not easy to verify,and it does not have file applicability.The data stored in the cloud can be divided into single data file storage and multiple replica file storage.For the two different storage scenarios,the deterministic deletion mechanism of data will also be different.To this end,the main work of this dissertation includes:(1)For single data files,a deterministic deletion method of cloud data based on access control strategy is proposed,which solves the single point of failure and time efficiency problems existing in the original deletion scheme,and adopts the mechanism of blockchain multi-CA and symmetric encryption.The combination with attribute-based encryption improves the security and efficiency of the overall scheme,and has the characteristics of fine-grained access.For the deletion of data,the method of obtaining the key after updating the attribute value and then updating the ciphertext,and combining with the blockchain technology,realizes the result verification after data deletion;(2)For multiple replica files,a deterministic deletion method of cloud data for multiple replica storage is proposed,which solves the problem of insecure key storage and incomplete deletion of multi-copy files.The key is stored in the blockchain network in the form of components,and the smart contract is called to store and distribute the key components.At the same time,a multiple replica associative storage mechanism is established to generate a pre-deletion sequence to ensure the complete deletion of data.The overall scheme combines blockchain technology to improve the security and reliability of key storage in the entire scheme,and to ensure the verification of results after data deletion.The work of this dissertation can ensure the security of data outsourcing storage and the verifiability of data deletion.Both methods combine blockchain technology to enable accountability in the event of a data leakage.In both schemes,the feasibility and performance advantages of the scheme are explained through security analysis and performance simulation,the security attributes in terms of data security and privacy are explained,and the deterministic deletion mechanism of data files in cloud storage scenario is verified to be well applicable. |
