As a certification center for JIT digital certificate authentication system, CA's core functions are certificate and CRL lifecycle management functions such as issuing, canceling, and renewing certificates, and issuing and issuing CRLs. It is the authentication authority of the digital certificate authentication system. By binding the identity information of the certificate holder and the public key held by the certificate and digitally signing it, it also guarantees the authenticity and integrity of the holder's public key and related information contained in the certificate.