- Edited
coffeefun This was mentioned in a post above. I hope I didn't miscommunicate. Let me try quoting it here; I hope I do it right!
I see, I must've missed that! I think that "attack channel" is very strong and scary wording. I'm assuming that what @DeletedUser115 means here is that if an app is not properly using FCM for notifications with Play Services (Signal is an example of an app that does this properly), you could be leaking your notifications to Play Services. It all goes back to trusting the developers of your apps to be doing things properly in the first place.
coffeefun This would be great! I abandoned WhatsApp, for example, on iOS because of this very issue. I have many friends and colleagues that still use it as their primary messenger, so it's complicated for me to abandon it. I've only managed to convert a subset of my contacts to Signal over the years.
Absolutely, you shouldn't have to stop using an app just because it insists on using an invasive permission (apps are fully capable of implementing a contact picker that allow you to choose specific contacts as far as I understand, but it's one of those things that we've never even seen, because no apps seem interested in using it). Storage Scopes were huge, and in my opinion is one of the greatest features that are unique to GrapheneOS. Contact Scopes will only make things better. :)
coffeefun Since it requires mutual consent between apps, I assume that even if Spotify wanted to secretly communicate with Signal, for example, that Signal would brush off those attempts, breaking the mutuality of that channel?
Correct, both apps would have to agree and explicitly define that they're open to communicating with one another.