It’s “wide open data” if app developers choose to build that way.
It’s not rocket science to obscure push notification data. Your beef should be with the app devs who don’t go the extra mile, not Apple.
It’s not rocket science to obscure push notification data. Your beef should be with the app devs who don’t go the extra mile, not Apple.
It's pretty simple: don't use iMessage if you value secure communication, since we know Apple gets hamstrung by the government at points. Devs building for the platform should be taken to task here because they need to be aware of and optimize around the data leaking issue, relying on the parent platform to always be a good steward is a recipe for disaster.
I did some anonymization across hundreds of millions of users for some GDPR stuff a few years ago. If I knew when you made a purchase, to within a day, for two separate one-off purchases of our products ... I could deanonymize you. Specifically just you. If you had a subscription payment, and I knew at least one payment you were late on, and the hour you eventually paid it ... I could deanonymize you down to a group of 3-4 people.
Correlation and timing are huge for deanonymizing things in otherwise anonymous data. We had to round our dates to the week to keep some of our analytical data anonymous.
> Just look for groups of people getting notifications at the same time.
In a sufficiently built system - like what Signal does, and like what most apps should be learning from - all the notification payload is getting is a "check for updates" command. You and literally everyone else are getting that generic notification all the time if you're in more than one chat. Just because Alice sent a message at 12:01PM and Bob received the generic "check me" notification at 12:02PM doesn't mean Bob necessarily received Alice's message specifically, because the notification has absolutely no concept of the messages period. Bob could have gotten that notification due to any of the other chats he's in.
At best the argument here is that the government could use the push notification token to link a Signal account to a real username via Apple, but if you're that paranoid you shouldn't use an iOS device anyway. You also likely wouldn't use Signal due to the phone number issue.