Generally speaking, https means that the server has a certificate.
In rare cases, the client will be required to have a certificate.
Therefore, when the client does not have a certificate, the server needs to ignore certificate verification.
Server verification stage:
1. The client sends a start message to the server to start a new session connection;
2. The server determines whether a new master key needs to be generated according to the customer's information, and if so, the server will include the information needed to generate the master key when responding to the Hello information of the customer;
3. The client generates a master key according to the received server response information, encrypts it with the server's public key and sends it to the server;
4. The server recovers the master key and returns the message authenticated by the master key to the customer, so that the customer can authenticate the server.