Privacy Protection Model for Blockchain Data Sharing Based on zk-SNARK

In the era of big data, data sharing and communication play a crucial role. The blockchain data sharing model based on ciphertext policy attributed-based encryption (CP-ABE) is an existing solution to data sharing. However, it puts the access policy and attributes directly on the blockchain, so every one in the blockchain can access these access policies and attributes, which will cause privacy leakage. To solve this problem, a privacy protection model based on zk-SNARK is proposed in this paper. The blockchain double-chain structure was applied in this model, and the fine-grained access control of data sharing was realized based on CP-ABE scheme. At the same time, zk-SNARK technologies were adopted to protect sensitive access policies and sensitive attributes from disclosure, effectively defending the privacy of users when data sharing in blockchain.