Research Of Distributed Privacy Data Protection Technology Based On Blockchain

In recent years,the total amount of data has grown exponentially in the past ten years.At the same time,users' personal data has also been digitized to a great extent,and the data itself has been endowed with a lot of value,which is an important part of the economy and society.As a valuable asset,the need for secure storage and sharing of data has ballooned.In the past,users were accustomed to storing data in third-party data storage service providers.However,the single point of failure of traditional centralized data storage platforms could easily lead to user data loss,misuse of user data caused by a crisis of trust,and privacy leakage.The decentralized nature of blockchain technology solves trust problems in many fields,and it is a topic worthy of research that a blockchain-based distributed privacy data protection scheme is applied to protect user privacy information.This thesis focuses on improving traditional centralized data privacy and security issues.The main research contents of this thesis are:(1)Introduces the significance of research on data privacy protection,summarizes the domestic and foreign status quo of privacy data protection research based on blockchain,and outlines related theories such as elliptic curve cryptography,attribute-based encryption,and national secret algorithms.(2)Aiming at the difficulties of data security sharing and easy leakage of private information in the traditional centralized data storage environment,a distributed user sensitive data security storage and sharing scheme combining blockchain technology and national secret algorithm is studied.The improved national secret SM2 digital signature algorithm is used to hide sensitive data,and to ensure that visitors can verify the authenticity of the data after a part of the content has been hidden;through blockchain and smart contracts,user attributes can be judged,and the central A streamlined access control mechanism.After analysis,the correctness of the scheme is proved,and it has advantages in improving the overall security and performance.(3)Aiming at the problems of low policy efficiency,difficulty in accountability for key leakage and lack of flexibility for policy changes in the data security storage and sharing model based on blockchain and attribute-based encryption.An efficient dynamic policy attribute-based encryption scheme based on blockchain is studied.By improving the CP-ABE algorithm logic,the data sharing granularity is subdivided into attribute levels,and it also supports tracking malicious users who leak private keys,and realizes data holding.The user can flexibly update the access control policy.Finally,the correctness and effectiveness of the proposed scheme are verified through theoretical analysis and performance analysis.The innovations of this thesis include:(1)Propose a distributed user sensitive data security storage and sharing scheme based on the blockchain and the national secret SM2 algorithm.Under this model,the data generator and the data holder are not the same subject,and the scheme is suitable for the data holder.Scenarios where electronic qualification certificates containing private information are issued.By improving the SM2 signature algorithm,the data holder can hide the sensitive data in the file when sharing data,and calculate a verifiable signature for the remaining data.The data visitor can verify the extracted signature without interacting with the data generator.correctness.At the same time,the scheme uses the characteristics of the blockchain to build a decentralized access control mechanism,and automatically executes the judgment of visitor attributes through smart contracts.The whole process does not require the participation of a third-party trusted organization.(2)An efficient dynamic policy attribute-based encryption scheme based on blockchain is proposed.In the scheme,the data holder has absolute control over the data.The introduced Update Policy algorithm achieves the effect of flexible update of the access policy by the data holder.At the same time,in the key generation process of the attribute-based encryption algorithm,not only the user attribute set,but also the user's identifiable identity information is embedded,which realizes fine-grained access control and responsibility traceability of private data.Finally,the scheme analysis shows that the scheme has advantages in shortening the length of ciphertext and key,and improving the efficiency of key generation,encryption and decryption,Effectively reduce the computational overhead caused by the bilinear pairing operation in the CP-ABE algorithm.