How secure are apple APNS push notifications?

Question

Does anyone know where the vulnerabilities are in Apple's APN push notification services?

We can ensure that our notifications are sent securely to Apple, so we just need to know whether they can be intercepted from that point?

Motivation: We have built an iOS messaging app that we are making as a 100% secure solution, with some features that have never been exploited before in security.

Answer 1

Apple released the UNNotificationServiceExtension last year, allowing developers to send fully-encrypted notification payloads through APNS and then let the app on the end-user's device itself do the decryption (or load any additional supporting data) before displaying the notification:

The UNNotificationServiceExtension class provides the entry point for a Notification Service app extension, which lets you customize the content of a remote notification before it is delivered to the user. A Notification Service app extension does not present any UI of its own. Instead, it is launched on demand when a notification of the appropriate type is delivered to the user’s device. You use this extension to modify the notification’s content or download content related to the extension. For example, you could use the extension to decrypt an encrypted data block or to download images associated with the notification.

My team is investigating this further as a means to send useful notifications in a fully HIPAA-compliant manner, with no ability for Apple to see the plaintext of the notification. We're optimistic.