1. Configure server: Nginx

Create the certificate:

$ sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/ssl/private/nginx-selfsigned.key -out /etc/ssl/certs/nginx-selfsigned.crt

Create a strong Diffie-Hellman group:

$ sudo openssl dhparam -out /etc/ssl/certs/dhparam.pem 2048

Create a new configuration snippet file for Nginx:

$ sudo nano /etc/nginx/snippets/self-signed.conf

Add:

ssl_certificate /etc/ssl/certs/nginx-selfsigned.crt;
ssl_certificate_key /etc/ssl/private/nginx-selfsigned.key;

Create a configuration snippet with strong encryption settings:

$ sudo vim /etc/nginx/snippets/ssl-params.conf

Add:

# from https://cipherli.st/
# and https://raymii.org/s/tutorials/Strong_SSL_Security_On_nginx.html

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_prefer_server_ciphers on;
ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH";
ssl_ecdh_curve secp384r1;
ssl_session_cache shared:SSL:10m;
ssl_session_tickets off;
#ssl_stapling on;
#ssl_stapling_verify on;
resolver 8.8.8.8 8.8.4.4 valid=300s;
resolver_timeout 5s;
# Disable preloading HSTS for now.  You can use the commented out header line that includes
# the "preload" directive if you understand the implications.
#add_header Strict-Transport-Security "max-age=63072000; includeSubdomains; preload";
#add_header Strict-Transport-Security "max-age=63072000; includeSubdomains";
add_header X-Frame-Options DENY;
add_header X-Content-Type-Options nosniff;

ssl_dhparam /etc/ssl/certs/dhparam.pem;

Configure Nginx site to use certificate:

server {

    listen 443 ssl;
    server_name example.com;
    include snippets/self-signed.conf;
    include snippets/ssl-params.conf;

    #...
}

2. Configure computer: macOS

From local computer, download the certificate:

$ scp user@host:/etc/ssl/certs/nginx-selfsigned.crt ~/cert.crt

Open the file with the Keychain Access utility:

$ open cert.crt

Add the certificate to the System keychain (not login), authenticate.
After it has been added, double-click it, authenticate again.
Expand the "Trust" section.
Set "When using this certificate" to "Always Trust"

That's it! Close Keychain Access and restart Chrome, and your self-signed certificate should be recognized now by the browser.

Sources :

pavanyogi/self-signed-ssl-certificate.md

1. Configure server: Nginx

2. Configure computer: macOS