Push notifications
[!toc] Table of Contents
Deleted messages can be recovered through push notification cache
Push notifications are those nice little messages on your lock screen, that show you previews of the messages you received.
[!warning] Warning {static}
In early 2026 it became public that the FBI could recover signal messages on an activists iPhone through iOS’s own push notifications, although the > activist had self-destructing messages enabled and deleted their entire Signal app before the confiscation.
The problem is that the operating system “caches” the content of the push notification on it’s own storage, meaning it stores your messages outside of the app itself. Thus, deleting messages inside of the messenger itself won’t delete the copies in the operating systems cache.
[!technical] What is caching?
Caching is a technique used in computing to store copies of data temporarily, allowing for faster access to that data in the future. It helps improve performance by reducing the time it takes to retrieve frequently accessed information.
This is also true for self-deleting messages e.g. on Signal, which we recommend as a security feature.
[!tip] Tip {static}
The only way to prevent the operating system from caching your messages, is to stop the app from displaying sensitive content in those push notifications.
Preventing caching can be done per app, as far as the single app provides such settings. See our instructions for disabling sensitive content in signal notifications in Signal.
Information leak through notifications on lock screen
It is also recommended to completely disallow sensitive content showing up on your lock screen for all apps on the operating systems level in you phones settings.
[!tip] See our recommendation on that for GrapheneOS.