Research On Blockchain Privacy Protection Scheme Based On Zero-knowledge Proof Technology

Blockchain is currently widely used in various industries due to its characteristics of decentralization,non-tampering,and openness.In the medical claims industry,although blockchain can effectively solve the problem of medical claims transactions being tampered with and denied,the leakage of medical data is becoming more and more serious.Therefore,in this thesis,a blockchain medical claims privacy protection scheme based on zero-knowledge proof is constructed.The works of this thesis are as follows:1.A medical claim insurance scheme based on zero-knowledge proof is proposed.Firstly,our scheme combines zero-knowledge succinct non-interactive arguments of knowledge(zkSNARK)technology and digital signature technology to verify the validity of input data;Secondly,a blockchain account model is introduced for our scheme,and under the assumption of Decision Bilinear Diffie-Hellman(DBDH),the non-interactive zero-knowledge proof and the homomorphic encryption algorithm are used to ensure the legitimacy and privacy of transactions between different accounts in the blockchain;Combining Schnorr protocol and Fiat Shamir heuristic method to ensure the legitimacy and privacy of users’ identities.Finally,the security proof of the proposed scheme is given,and the performance of our scheme is compared with other schemes,it is proved that our scheme has more privacy protection characteristics.And the experimental simulation of our scheme is constructed,the experimental results show that the communication overhead,time overhead required by our scheme are low.The performance analysis and simulation experiments show that our scheme has privacy protection characteristics and effectiveness.2.Combining the proposed medical claim insurance scheme based on zero-knowledge proof with homomorphic proxy re-encryption technology,a medical claim insurance scheme based on homomorphic proxy re-encryption and zero-knowledge proof is proposed.And an additive homomorphic proxy re-encryption algorithm with privacy protection is constructed,the communication overhead of our scheme is reduced by performing additive homomorphism operations on ciphertext encrypted with different keys,and the medical claim data sharing with privacy protection is realized between the patients and the insurance companies.Finally,the security analysis of our scheme is given,it shows that our scheme has the characteristics of resisting collusion attacks.And the experimental simulations are performed on our scheme under the condition of inputting different number of data characteristic values,The experimental data shows that when the number of input data characteristic values is taken as a low dimension,the time cost of the proposed scheme is very small.The theoretical analysis and the experimental simulation demonstrate the effectiveness of the proposed scheme,our scheme not only ensures the privacy of medical claim data,but also greatly reduces its communication overhead.