# A Data Sharing Scheme for GDPR-Compliance Based on Consortium Blockchain
###### Abstract  
After the General Data Protection Regulation (GDPR) was introduced, some organizations and big data companies shared data without conducting any privacy protection and compliance authentication, which endangered user data security, and were punished financially for this reason. This study proposes a blockchain-based GDPR compliance data sharing scheme, aiming to promote compliance with regulations and provide a tool for interaction between users and service providers to achieve data security sharing. The zero-knowledge Succinct Non-Interactive Arguments of Knowledge (zk-SNARK) algorithm is adopted for protecting data and ensure that the user's private data can satisfy the individual requirements of the service provider without exposing user data. The proposed scheme ensures mutual authentication through the Proof of Authority consensus based on the Committee Endorsement Mechanism (CEM-PoA), and prevents nodes from doing evil using the reputation incentive mechanism. Theoretical analysis and performance comparison indicate that the scheme meets the confidentiality, availability, and other indicators. It has superiority in efficiency and privacy protection compared with other schemes.  
data security; privacy-preservation; big data; blockchain; GDPR +
Footnote †: journal:  
0000-0001-999-4000-0001-9999-4000-0001-9999-4000-0001-9999-4000-001-9999-4000-001-9999-4000-001-9999-4000-001-9999-40001-9999-40001-9999-4000  
protection based on the consortium blockchain, it will play a practical role in the personal data sharing scenario under the GDPR. The main contributions of this paper are listed as follows:  
1. This paper designs a blockchain-based data sharing scheme to achieve GDPR compliance and secure data sharing. In the proposed scheme, the blockchain ensures traceability.
2. The proposed scheme employs the zk-SNARK algorithm to guarantee the availability and privacy-preservation of data when interacting with smart contracts. Users construct zero-knowledge proofs and submit them to the smart contract to ensure that privacy data can meet service provider's requirements and will not leak. In addition, confidentiality is guaranteed by symmetric encryption.
3. After the success of verification, transactions between the user and the service provider are published on the blockchain. We have designed a PoA consensus algorithm based on a committee endorsement mechanism to ensure data integrity.
4. In order to prevent nodes from doing nothing or doing evil, we apply identity reputation as an incentive mechanism to ensure mutual authentication.
5. Performance analysis shows that this solution can ensure regulatory traceability, mutual authentication, and other indicators presented in Section 5. Compared with previous work, the proposed scheme in this paper is feasible and efficient.  
The proposed solution can ensure the security and privacy of data, without affecting the company's or organization's ability to provide personalized services. Based on the results of our contributions, we believe the design conception of our scheme is helpful to researchers who continue their research in the field of data sharing.  
The structure of this paper is presented as follows: Section 2 introduces the background and related work, including GDPR and blockchain-related technologies. In Section 3, we clarify the model of the scheme. Section 4 illustrates the specific implementation details. The performance analysis and evaluation of the proposed scheme are performed in Section 5. Section 6 summarizes the work of this paper and discusses the future research directions.