Citation:
Because the username and password are not encrypted, and the target server's identity is not authenticated by the browser, basic authentication alone is not secure. You can improve security by using a secure transport mechanism such as HTTPS, or security at the network level such as a VPN. However, if you switch to HTTP (after authenticating with basic authentication and HTTPS), your browser continues to send your username and password with each subsequent request in cleartext until you exit.
Et donc c'est la m.....