Verifying Privacy-Preserving Financing Orders on a Consortium Blockchain Based on zk-SNARKs

Due to its efficiency, low overhead, and high scalability, consortium blockchain has been deeply applied in various fields of society. Order financing is one of the scenarios of applying consortium blockchain. Since data on the consortium blockchain is available to the blockchain members, information of a financing order written directly to the blockchain will leak the commercial privacy of the purchaser and supplier. Therefore, the financing order data should be encrypted when published as a transaction on the consortium blockchain. However, the investor needs to verify the financing order data on a consortium blockchain before loaning money to the supplier. It is tricky to efficiently satisfy the verifiability of encrypted financing order data on the consortium blockchain. This work proposes VmppOrder, a verifiable model for privacy-preserving financing orders on a consortium blockchain based on zero-knowledge Succinct Non-interactive ARguments of Knowledge (zk-SNARKs). By the supplier publishing zero-knowledge proofs generated from the financing order, the investor can verify the encrypted financing order published on the consortium blockchain without decrypting it. We elaborate on the specific construction of VmppOrder and analyze the security of the constructed circuit with zero-knowledge proof. We implement a prototype of the model on Hyperledger Fabric based on Libsnark and conduct comprehensive experiments to evaluate its performance. Our experimental results validate the efficiency of the proposed model. Its order proof generation takes about 6.31 seconds, the order verification takes only 2.58 milliseconds, and the transaction processing speed is about 660 transactions per second on a moderately equipped machine.