WooCommerce and Amazon S3 Bucket

I want to sell digital files in WooCommerce. These files are stored in an Amazon S3 bucket. How can I authorize my WooCommerce store to access the files in my bucket when a customer makes a purchase?
I don’t want to make my S3 bucket public and add the URL to files as a part of my product setup. I am looking for a way to secure the files and still allow WooCommerce to deliver them when a customer makes a purchase.
Thank you