A Novel Distributed CA System Based on Blockchain

In the PKI-CA system with a traditional trust model based on trust chain and centralized private key management, there are some problems with issuing certificates illegally, denying issued certificates, tampering with issuance log, and leaking certificate private key due to the excessive power of a single CA. A novel distributed CA system based on blockchain was constructed to solve the problems. The system applied blockchain and smart contract to coordinate the certificate issuing process, and stored the issuing process logs and information used to verify certificates on the blockchain. It guaranteed the non-tamperability and non-repudiation of logs and information. Aiming at the disadvantage of easy leakage of private keys in centralized management mode, the system used the homomorphism of elliptic encryption algorithm, CPK and transformation matrix to generate and store user private keys safely and distributively. Experimental analysis showed that the system can not only overcome the drawbacks of the traditional PKI-CA system, but also issue certificates quickly and save as much storage as possible to store certificate private keys.