FBI used iPhone notification data to retrieve deleted Signal messages • Hacker News Board

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#251

Post by anon84873628 » Fri, Apr 10, 2026, 6:45 PM UTC

OutOfHere wrote: post #241

jacquesm wrote: post #212

Earlier quoted context omitted.

People keep pushing signal because it is supposedly secure. But it runs on platforms that are so complex with so much eco system garbage that there is no way know even within a low percentage of confidence if you've done everything required to ensure you are communicating just with the person you think you are. There could be listeners at just about every layer and that is still without looking at the meta-data angle…

There is nothing secure about sending encrypted content to notifications. If it were secure, it would only notify that there is a message, with no details included.

Once again there is a trade off between security and user convenience.

If security is the main differentiator then app should start in the most secure mode possible. Then allow users to turn on features while alerting them to the risks. Or at least ask users at startup whether they want "high sec mode" or "convenient mode".

As the app becomes more popular as a general messaging replacement, there will be a push towards greater convenience and broad based appeal, undermining the original security marketing as observed here.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#252

Post by inemesitaffia » Fri, Apr 10, 2026, 6:47 PM UTC

scarecrowbob wrote: post #190

seethishat wrote: post #160

A lot of dumb criminals seem to carry smart phones. The irony.

Probably, but these are people who are being charged for political "crimes" brought mostly because the government doesn't think people have a right to protest. While it's unsurprising that the citizen who discharged their weapon was tried for this, most of the other folks were just doing run-of-the-mill protest stuff. I also get that in Texas they are fine "criminalizing" protesting, but that's just part of its hyper…

They are part of a larger direct action group.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#253

Post by microtonal » Fri, Apr 10, 2026, 6:49 PM UTC

AJ007 wrote: post #247

microtonal wrote: post #237

Earlier quoted context omitted.

I think one of the main issues is that end-to-end message encryption is a sham as long as backups are not encrypted. I could have good device security, but if the person I'm talking to does not use ADP, iMessage and WhatsApp messages get backed up with only at-rest encryption (I think Signal opts out of standard iOS backups) and possibly the same for backups of the iPhone notification database (which the article sugg…

"end-to-end message encryption is a sham as long as" -- I agree with that but would add even more caveats. If someone can't list those caveats off the top of their head they shouldn't be pretending they aren't able to communicate securely. Just look at Salt Typhoon, every single person should be way more paranoid than they are, including government & agency officials. The attach surface and potential damage - financi…

I mean the Hungarian minister of Foreign Affairs briefed Lavrov on internal EU matters and there are recordings of one or more calls. It seems that opsec is bad at pretty much every level.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#254

Post by tapoxi » Fri, Apr 10, 2026, 6:59 PM UTC

microtonal wrote: post #237

upofadown wrote: post #180

Putting on my user hat... "OK. Signal has forward secrecy. So messages are gone after I receive them. Great!" Oh, you didn't turn on disappearing messages? Oh, right, then forensic tools like Cellebrite can get them. You have to turn on disappearing messages. The default is off. Oh, you did turn on disappearing messages? We send the messages in notifications. So the OS can keep them. Turns out Apple was doing that. T…

I think one of the main issues is that end-to-end message encryption is a sham as long as backups are not encrypted. I could have good device security, but if the person I'm talking to does not use ADP, iMessage and WhatsApp messages get backed up with only at-rest encryption (I think Signal opts out of standard iOS backups) and possibly the same for backups of the iPhone notification database (which the article sugg…

Signal data is not backed up, they have a local backup solution and an in-app e2e cloud backup for $2/month.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#255

Post by Zak » Fri, Apr 10, 2026, 7:06 PM UTC

satvikpendem wrote: post #170

greysonp wrote: post #115

Earlier quoted context omitted.

Signal developer here. Not entirely sure what you're saying. I'm only an Android guy, but FCM messages are certainly one trigger that can allow an app process to run, but it's not the only trigger. You can schedule system alarms, jobs, etc. And the notification does not need to be provided by the FCM message. In our case, the server just sends empty FCM messages to wake up the app, we fetch the messages ourselves fro…

Sure but it needs to go through Firebase regardless of the content of the notification message, I do not believe there is a way to use a third party notification service which does not depend on Firebase.

It doesn't. The API for displaying a notification is purely local.

Receiving a ping from Firebase Cloud Messaging triggers the app to whatever it does in order to display its notification. In the case of Signal, that probably means something like fetching the user's latest messages from the server, then deciding what to show in the notification based on the user's settings, metadata, and message content.

Here's example code for using FCM to show a notification. In this case, the notification content also passes through FCM, but Signal does not do that. https://www.geeksforgeeks.org/android/how-to-push-notificati...

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#256

Post by nine_k » Fri, Apr 10, 2026, 7:13 PM UTC

gertop wrote: post #228

nine_k wrote: post #109

Earlier quoted context omitted.

If you care about security at all, you disable any previews on the lock screen. The lock screen is by definition visible to anyone without any authorization. Showing anything on it immediately destroys any secrecy. It must be obvious to anyone capable of elementary logic inference. If you don't know how to disable it, you use your favorite search engine / LLM / knowledgeable relative to find out, and disable it. But…

Disabling notification preview in the operating system settings doesn't prevent the issue, they're still saved in the database. The only way they're not saved is to disable name/content in signal itself. Maybe you're not as capable of elementary logical inference as you thought?

Disabling may be not sufficient (which is pretty insidious), but I still posit that enabling message preview is guaranteed secrecy loss.

But indeed, the idea that disabled notifications are still stored, and not directed to /dev/null immediately, cannot be inferred from just observing the behavior of the phone UI.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#257

Post by commandersaki » Fri, Apr 10, 2026, 7:20 PM UTC

sillysaurusx wrote: post #203

commandersaki wrote: post #99

Earlier quoted context omitted.

So I wonder about this. The quote from the 404 media article [0] is: “We learned that specifically on iPhones, if one’s settings in the Signal app allow for message notifications and previews to show up on the lock screen, [then] the iPhone will internally store those notifications/message previews in the internal memory of the device,” a supporter of the defendants who was taking notes during the trial told 404 Medi…

I think that’s a little nutty. People go to signal for secure messaging. That’s their entire brand. An insecure by default setting is the wrong setting, even if it nets them a lot of tech illiterate users. Compromising the security of the system defeats the entire point of using Signal instead of some other messenger. By this logic, you, me, and everyone else using the defaults are using bad opsec. Doesn’t that strik…

I posted this elsewhere and I said this in my post, but the default setting is actually not the insecure one: https://files.catbox.moe/3gwjoy.png (supposing that previews are stored encrypted when locked which is what the 404media passage implies and nothing to say to the contrary).

This user went out of their way to show previews on the lock screen, that is an OPSEC failure, even if you do not consider the acquisition of the messages digitally.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#258

Post by satvikpendem » Fri, Apr 10, 2026, 7:24 PM UTC

Zak wrote: post #255

satvikpendem wrote: post #170

Earlier quoted context omitted.

Sure but it needs to go through Firebase regardless of the content of the notification message, I do not believe there is a way to use a third party notification service which does not depend on Firebase.

It doesn't. The API for displaying a notification is purely local. Receiving a ping from Firebase Cloud Messaging triggers the app to whatever it does in order to display its notification. In the case of Signal, that probably means something like fetching the user's latest messages from the server, then deciding what to show in the notification based on the user's settings, metadata, and message content. Here's examp…

Sorry I should clarify, by "it" I meant any sort of ping must go through Firebase Cloud Messaging, not that the message content itself goes through Firebase.

Looks like there is a way to bypass Firebase by using something like UnifiedPush which runs a perpetual background process that acts similar to Google Play Services to pick up notifications from the server and calls the local notification API.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#259

Post by sph » Fri, Apr 10, 2026, 7:28 PM UTC

AJ007 wrote: post #247

microtonal wrote: post #237

Earlier quoted context omitted.

I think one of the main issues is that end-to-end message encryption is a sham as long as backups are not encrypted. I could have good device security, but if the person I'm talking to does not use ADP, iMessage and WhatsApp messages get backed up with only at-rest encryption (I think Signal opts out of standard iOS backups) and possibly the same for backups of the iPhone notification database (which the article sugg…

"end-to-end message encryption is a sham as long as" -- I agree with that but would add even more caveats. If someone can't list those caveats off the top of their head they shouldn't be pretending they aren't able to communicate securely. Just look at Salt Typhoon, every single person should be way more paranoid than they are, including government & agency officials. The attach surface and potential damage - financi…

Given the shoddy state of network security at large, especially on infrastructure projects (power plants, hospitals, dams, etc.) I always feel like major governments sit on so destructive potential to disrupt communications and anything connected to the Internet of its adversaries to have mutual assured destruction potential of a nuclear bomb.

No one’s crazy enough to push that button, because once you do there is no turning back.

Re: FBI used iPhone notification data to retrieve deleted Signal messages

#260

Post by izacus » Fri, Apr 10, 2026, 7:30 PM UTC

aftbit wrote: post #86

nickburns wrote: post #53

Earlier quoted context omitted.

Yes. And technically, from a privacy perspective, it's even worse than that. What's additionally happening is they're still 'syncing' back to Apple servers via APNS (and to Alphabet servers via Firebase on Android)—even with notifications completely disabled , that's correct. If the app generates them, the OS receives them. That's why the Signal app offers this setting.

Wait... why does Signal need to send notification content to Firebase to trigger a push notification on device? I would instead expect that Signal would send a push to my Android saying nothing more than "wake up, you've got a message in convo XYZ", then the app would take over and handle the rest of it locally. I also didn't realize that Android stores message history even after I've replied or swiped them away. Tha…

Android doesn't store message history unless you explicitly enable that feature and neither does Signal send message content to Firebase.

You're angry about a huge amount of outright misinformation here.