this post was submitted on 07 Apr 2026
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283
Signal messages retrieved from iOS notification, as seen in Prairieland federal trial (media.fedia.io)
submitted 4 days ago by frocalannifo@fedia.io to c/technology@lemmy.world
85 comments fedilink hide all child comments
 

TLDR: signal content in Apple notification can be retrieved even after signal app deletion.

I saw from this reddit thread: Signal messages retrieved from iPhone after uninstalling app. : signal

Referencing this news article: Pretti Killing May Affect ICE Prairieland "Antifa Cell" Terrorism Trial

The mention of signal is in court documents here: March 10: Federal Trial Day 12 - Support the Prairieland Defendants

Signal chat evidence from Sharp’s device (Exhibit 158):
Messages were recovered from Sharp’s phone through Apple’s internal notification storage — Signal had been removed, but incoming notifications were preserved in internal memory. Only incoming messages were captured (no outgoing).

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[–] anon_8675309@lemmy.world 38 points 3 days ago (4 children)

That’s my biggest issue with notifications. Notifications should just notify you that something happened and you need to open the app to find out. Carrying actual data ON the notification is a no-no.

But what do I know, I’m an old developer not one of these modern vibe kiddies.

[–] WolfLink@sh.itjust.works 10 points 2 days ago

Signal already has that setting. It’s up to the user to decide their level of convenience vs security.

[–] phx@lemmy.world 3 points 2 days ago

Yeah. It's not just signal either that could be an issue. Sure, I want my private messages to be private, but there are financial apps, business email, and many other bits of very sensitive information that could be captured in those messages

[–] NotMyOldRedditName@lemmy.world 3 points 3 days ago* (last edited 3 days ago)

The actual notification telling you there is a message shouldn't contain the content if its sensitive, it should only carry an ID to said message, and im certain this is what signal does. Thats like the most utter basic thing about notifications.

Once that notification arrives, the system decides what to show you after fetching the message from the ID in the background. You can opt to keep that private or show it.

In this case if you opt to show it, it leaks.

[–] baggachipz@sh.itjust.works 4 points 3 days ago (2 children)

A notification doesn’t have to carry any data in its payload; Signal devs could take care of that.

[–] rezifon@lemmy.world 19 points 3 days ago (6 children)

Signal has supported this for many years. Users can choose full content notifications, name only, or no-content notifications.

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[–] SnoringEarthworm@sh.itjust.works 106 points 4 days ago* (last edited 4 days ago) (6 children)

Basically, they didn't do this:

(I'm on Android, so I don't know what the options look like in iOS, but they should be identical.)

[–] RIotingPacifist@lemmy.world 43 points 4 days ago (2 children)

It would be nice if Signal let you do this per conversation.

It's sort of a victim of its own success, I use it for both things that do and don't require opsec

[–] Quill7513@slrpnk.net 8 points 3 days ago (1 children)

and on some level it's important for good opsec that things that don't require opsec be done with good opsec

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[–] rezifon@lemmy.world 3 points 3 days ago

I imagine that the signal devs viewed it as a similar concern as when you mistype your password the error message doesn’t give you any way to know if the password is wrong or if the account doesn’t exist.

If only some of your notifications are sanitized then those are the suspicious ones. If all of your notifications are sanitized then none of them are suspicious. Or, at least, they’re all equally suspicious, opaque, and unidentifiable.

[–] Bazoogle@lemmy.world 18 points 3 days ago (4 children)

You also don't need to do this on Android unless you are concerned about random people seeing the messages on your screen. Signal on Android does not use Google's push notification service

[–] Quexotic@infosec.pub 10 points 3 days ago

You most certainly do. I looked in my notification history in my founding of signal messages.

Then I turned off my notification history.

[–] Quill7513@slrpnk.net 6 points 3 days ago

as far as i know signal uses Google's notification service and if you want it to not you need to use Molly

[–] 0_o7@lemmy.dbzer0.com 5 points 3 days ago

Signal on Android does not use Google's push notification service

Source? I'm pretty sure it falls back to a different mechanism when it doesn't find google services. And that is only on the version downloaded from their website.

https://github.com/signalapp/Signal-Android/issues/13290

[–] electric_nan@lemmy.ml 7 points 3 days ago (10 children)

It's not about how it's pushed. It's how it's displayed (and stored) on the phone.

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[–] Kupi@sh.itjust.works 11 points 3 days ago* (last edited 3 days ago)

They are similar

[–] Crackhappy@lemmy.world 6 points 3 days ago

Thank you internet stranger. I'm going to do this but fuck me if I can get my family to change their settings. They don't even know they can create a poll.

Don't ask me. I made all of you admins do I don't have to answer questions like how do I make a poll. Click the + button. Yeah. The one on your fucking screen right now.

No grandpa. We are not trying to figure out who is trans. No popop none of are naxies (I hope)

Anyway, click the +. Right there. That is how you create a poll.

[–] napkin2020@sh.itjust.works 6 points 3 days ago* (last edited 3 days ago) (1 children)

They shouldn't have had to do this though.

[–] Quill7513@slrpnk.net 8 points 3 days ago

there's a lot of things under fascism that shouldn't be needed

[–] blargh513@sh.itjust.works 3 points 3 days ago* (last edited 3 days ago)

This is the problem, not what is shown in the per-app notifications. Don't turn on notification history.

[–] ZoteTheMighty@lemmy.zip 57 points 3 days ago (3 children)

But Apple told me in an ad that they're better for privacy?!?

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[–] scytale@piefed.zip 54 points 4 days ago* (last edited 4 days ago) (3 children)

I learned about this a couple of months ago and I've since disabled previews in notifications. It's unfortunately the nature of how notifications are delivered to you. You should be fine by disabling message previews in your notification settings.

[–] in_my_honest_opinion@piefed.social 35 points 4 days ago (1 children)
[–] spectrums_coherence@piefed.social 14 points 3 days ago (4 children)

I think on android, signal do not use Google's push notification. They simple send a dummy push, and the signal app wakes up to retrive the latest message directly from signal server.

So Google never have your notification content. I am not sure if they do the same on iOS.

That being said if your attack model includes people reading your notification lock screen, then you should disable showing signal notification.

[–] in_my_honest_opinion@piefed.social 9 points 3 days ago

The message preview notification is handled similarly in IOS and Android. The issue isn't people seeing the notification, it's that the content of the message being passed to the phone's launcher. Which is unencrypted.

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[–] eleijeep@piefed.social 12 points 4 days ago (1 children)

Does that actually prevent the app from sending the content through Apple’s servers or does it just prevent iOS from showing it in the notification area?

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[–] Bazoogle@lemmy.world 11 points 4 days ago* (last edited 4 days ago) (1 children)

It's worth noting apps can avoid this on Android: https://tuta.com/blog/google-push-alternative#alternatives-to-google-push

Any FDroid app cannot use Firebase for push notifications since it's proprietary: https://forum.f-droid.org/t/firebase-allowed-in-fdroid-apps/7540

[–] WhyJiffie@sh.itjust.works 7 points 3 days ago* (last edited 3 days ago)

It's not because of push notifications. the message is not sent to firebase, just a signal that the app should do a refresh.

It's because the system saves the notifications apps posted to the notification menu.

but yes. don't use firebase push notifications if you can avoid it. use a unifiedpush based system. base signal app does not support it, only molly. there are some difficulties though with that that are unique to signal.

[–] HumbleExaggeration@feddit.org 35 points 4 days ago* (last edited 3 days ago) (1 children)

So you are telling me an app is encrypting the shit out of every message so it can secretly delivered to another person. An then the persons phone decrypts the message and broadcasts it to an apple server, so it can get send back and make the phone go 'ding'?

Shouldnt the notification be handled inside signal somehow, so this is the only app with the decrypted message?

What is next, everything from my ram needs to go through google servers to be transmitted to my display?

[–] RunningInRVA@lemmy.world 56 points 4 days ago

The Signal server would send a backend notification to the client app via the Apple Push Notification Service. The app is then able to wake up, at which point it fetches new messages (securely) from the Signal servers. The app then generates a local notification with a preview of the received message. iOS is then logging those messages.

[–] ImmersiveMatthew@sh.itjust.works 4 points 2 days ago

Just more evidence that Apple is not that concerned about privacy as this is a hole they absolutely could close.

[–] TheFrirish@tarte.nuage-libre.fr 9 points 3 days ago (4 children)

Honestly I have a much much much MUCH MUCH bigger issue with the fact that it is an American and Centralised service.

FBI still can't access it though.

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[–] Bazoogle@lemmy.world 12 points 4 days ago (8 children)

This is not always the same on Android. Any app from FDroid will not use Google's push notification service because it is proprietary, meaning it violates the rules for FDroid. Signal does not use Google's notification service

[–] napkin2020@sh.itjust.works 4 points 3 days ago

I'm pretty sure Signal has two builds: one with Google service and one without.

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[–] x00z@lemmy.world 10 points 3 days ago (2 children)

This has been done before and is already pretty well known.

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[–] woelkchen@lemmy.world 12 points 4 days ago (5 children)

Well, of course. All notification contents go through Apple's servers (or Google's in case of Android).

[–] Bazoogle@lemmy.world 20 points 4 days ago* (last edited 4 days ago) (1 children)

Not all, no. There are alternatives on Android:

The good news is that alternative methods for push notifications are available, namely SSE (Server Sent Events) and WebSockets.

Additionally, a new open source project, UnifiedPush is becoming increasingly popular. UnifiedPush is an open source, private alternative to Google for notifications.

https://tuta.com/blog/google-push-alternative#alternatives-to-google-push

Signal for android uses web sockets for notifications

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[–] AbidanYre@lemmy.world 12 points 4 days ago (2 children)

Why would a notification need to leave my device at all?

[–] Goodlucksil@lemmy.dbzer0.com 12 points 4 days ago

Because it's FAANG

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