Allows you to store the files in internal-data://keys/ in XenForo's data registry.
Both functions can be enabled via options (do not need config.php edits).
Note: I know it's less than ideal to require the Cloudflare add-on to use this, but the necessary underlying filesystem changes are in that add-on (originally they were intended just for R2). You don't need to use that add-on for anything other than the filesystem changes (or don't need to use Cloudflare's service or even have a Cloudflare account).