Embed Notice

@jsq Hi Jesse!
Before talking about Sealed Sender specifically, it's worth calling out that Signal does not send any push content other than a flag that says: “Connect to the Web Socket” and retrieve some messages”. The content is then fetched and decrypted in a Notification Service Extension and then displayed as a local notification to the user.
https://github.com/signalapp/Signal-iOS/blob/b1027b670ea145073b12e5fb5c281a2facd3b61b/SignalNSE/NotificationService.swift#L105
APNS therefore never sees, even the Sealed Sender-encrypted ciphertexts, of the incoming messages.