A Privacy-Protecting Authorization System Based on Blockchain and zk-SNARK

With the rapid development of blockchain, many service providers tend to provide users with network resources and services on the basis of blockchain, and most network resources are inseparable from the authorization. However, the current authorization mechanism based on blockchain is not perfect, which is easy to cause the user's identity attributes to be leaked, and not conducive to protecting the privacy of users. In order to improve the authorization mechanism based on the blockchain and protect the user's privacy to the greatest extent during the authorization process, we proposed a privacy-protecting authorization system based on blockchain and zk-SNARK. First of all, SP can authorize users through the blockchain smart contract. Second, in the authorization process, we introduced zk-SNARK. Using the zero-knowledge property of zk-SNARK, the SP can still authorize the users without knowing the identity attribute value of the users. Therefore, the proposed system can better protect the users' attribute privacy. Finally, we analyze the security of the proposed system, and the results show that it is computationally infeasible for an attacker to attack the system.