Let me answer _. It's just that the relying party of electronic signature you mentioned is not expressed in the electronic signature law, just the relying party. So there are three aspects below, you can have a look!

There is no compulsory authentication system for electronic signature in Electronic Signature Law, but the asymmetric encryption of public key and the determination of the unique identity of the signer contacted by private key involved in digital signature will inevitably involve digital signature authentication. In the process of using digital signature and its authentication, at least three parties are involved, namely, electronic signer, electronic signature relying party and electronic authentication service provider.

The legal relationship between the electronic authentication service provider and the relying party is mainly the legal trust relationship. The legal obligation of the authenticator to the relying party is based on social credit, industry standards as professional authenticators and special provisions of the electronic signature law on authenticators.