I recently got an email about SSL certificate changes for anyone using the authorize.net API to process transactions. I use a cURL in PHP to call the following endpoint for all my payment processing:

https://api.authorize.net/xml/v1/request.api

I am confused by the whole certificate thing, I just call the endpoint with my merchant credentials in the XML, as far as I know. Do I need to do anything or install something on my server to keep it working? Or am I fine continuing to do what I have been doing?

Excerpt from the email I got: You must integrate and use the newly-issued Root and Intermediate (CA) SSL certificates from DigiCert by October 24 to avoid any disruptions.

I love the vague words "integrate and use". How do I integrate and then how do I use, in PHP and on my server?