In the real society, the resident identity card used to confirm identity is issued by the public security organ, which is an authoritative institution that everyone can trust. In the network environment, it is also necessary to have an authoritative organization that everyone trusts to issue electronic signature authentication certificates. This authoritative organization is the electronic signature authentication service provider (CA organization) mentioned in the Electronic Signature Law. Its main function is to issue electronic signature authentication certificates to electronic signers according to their applications. At present, e-sign has connected all 38 CA institutions in China.