Comment by SomaticPirate
2 days ago
This is well known in the op-sec communities. iOS and Android notifications route through their servers and can be stored indefinitely (ie especially under a court order) You need to disable the content previews if you want to be secure. But even the notification metadata can be quite valuable to law enforcement (who is messaging you, what time of day, etc.)
Also standard requirement on govt mobile devices to disable notifications. Mattermost provides this option at the server level to block notifications entirely for ios/android devices.
The article is specifically not referring to information that's sent to Apple servers - it's about information on the phone only, accessible through forensics tools with physical device access.
Signal's server-side push notifications only contain a "wakeup" message. The actual message popup is displayed after decrypting the message contents locally on the device. Of the things you mentioned, only the time of notification is visible to Apple/Google.
Fun fact, apps can't wake from APNS if the user killed the app (swipe up) last time instead of switching away normally. Apple publicly said something contrary to this at one point, so it might be surprising that Signal can work this way. The notification itself will still come through outside the app, so I wonder what you see, probably some placeholder text?
Yes there's a placeholder in that scenario Something like 'new message available' if I remember correctly (I'm no longer on iPhone, so can't verify)
You're thread-sliding, friend, and trying to diminish the major blow-up here. ALL notifications from banks, WhatsApp, Telegram you name it are stored indefinitely, and anyone with physical access to the phone and a cable can extract your entire history. This is NOT the same as them being stored at Apple or the NSA. Any shithead with a cable can do it.
If you run your own XMPP server, like Prosody, this issue is readily apparent. See, e.g., the options push_notification_with_body and push_notification_with_sender for https://modules.prosody.im/mod_cloud_notify
Ironically, I've got most notifications disabled because I simply find them annoying. I think SMS, phone calls and my CGM are the only things that cause my phone to regularly make noise.
*Google notifications, not all Android. Unified Push combined with a degoogled ROM works great to have convenience and security.