You can configure APJP to use a HTTPS connection:
EXAMPLE: in APJP.properties
PHP_PROXY_SERVER_URL=
https://domain.com:443/APJP.php
You can protect APJP.php using .HTACCESS BASIC or DIGEST
authentication
EXAMPLE: in APJP.properties
PHP_PROXY_SERVER_USERNAME=username
PHP_PROXY_SERVER_PASSWORD=password