Hey @jimstr,
Awesome to hear that you are already using an additional layer of encryption!
Two other resources that might help, but not formally state "compliance".
New Developer Documentation:
https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server
https://developer.apple.com/documentation/usernotifications/setting_up_a_remote_notification_server/sending_notification_requests_to_apns
Old Developer Documentation (My Preference):
https://developer.apple.com/library/archive/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/APNSOverview.html#//apple_ref/doc/uid/TP40008194-CH8-SW1
Neither answer the "compliance" question directly though outside of speaking abstractly to how the service works. One approach to take in a compliance report is to show what systems you have control over and those you do not. Showing that you have compliance within the systems that you are able to control (Certificate Pinning, KMS, etc.) with the ability to ensure cryptographic integrity to the client (assuming you also have client side protections in place) through untrusted space which is essentially the entire Internet because the client wouldn't have control over the client side network connection (assuming a BYOD approach) even with those protections in place (ISP Interference, etc.).
If I am able to find any more specific documents from Apple I will make sure to update the post!
Topic:
App & System Services
SubTopic:
Notifications
Tags: