How is certificate transfer carried out during HTTPS connection establishment?

During the establishment of an HTTPS connection, a TLS handshake occurs, during which the server sends its certificate to the client. This certificate contains the server's public key and confirms its authenticity, signed by a Certificate Authority (CA). The client verifies the certificate to ensure it is valid and matches the expected domain.

In Go, the crypto/tls package is used for working with HTTPS. When establishing a connection, the server automatically sends its certificate if it is configured in tls.Config.

Example of configuring an HTTPS server in Go:

package main

import (
    "crypto/tls"
    "log"
    "net/http"
)

func main() {
    srv := &http.Server{
        Addr: ":443",
        TLSConfig: &tls.Config{
            // Certificate and key are loaded automatically when the server starts
        },
    }

    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("Hello HTTPS"))
    })

    log.Fatal(srv.ListenAndServeTLS("server.crt", "server.key"))
}

Here, ListenAndServeTLS automatically loads the certificate and key and sends the certificate to the client during the TLS handshake.