There’s a difference between iOS killing the app and suspending it. When suspended an app remains in memory and the OS doesn’t give it any opportunities to run any code. When the user switches back the app resumes without any change in its state.
iOS is probably killing the Voyager app when it’s in the background because whatever you’re switching to is using a lot of memory.
On the phone you used to take the photo, turn on the personal hotspot.
So even with BFU, does the iPhone not connect to the internet? I guess i hadn’t noticed it doesn’t.
Well, it’s complicated. Most of these topics are. In BFU state, an iPhone (or iPad with cellular) with an active SIM and active data plan will connect to the Internet. It won’t connect to Wi-Fi at all. If you have USB restricted mode disabled and the right accessory connected it will connect to an Ethernet network, but that may fail if the network requires 802.1x and the credential is not available in BFU state. Similarly if USB restricted mode is disabled you can use tethering to a Mac to share its network.
For location, there’s two mechanisms. One mechanism relies on directly communicating with the device, which only works if the device has network.
The other mechanism is the “FindMy network” which uses a Bluetooth low energy (BTLE) beacon to let other nearby devices detect it, and they report that to FindMy. It’s a great technology. The way it uses rotating IDs preserves your privacy while still letting you locate your devices. I know that this works when a device is powered off but the battery is not completely dead. I’m not sure if it works in BFU state… my guess it that it does work. But this is not networking. It’s just a tiny Bluetooth signal broadcasting a rotating ID, so it’s one-way communication.
Other than that, I’m not as sure how things work. I believe Bluetooth is disabled by default in BFU state, but I suspect users can choose to re-enable Bluetooth in BFU state to connect to accessibility accessories. I’m not sure about the new emergency satellite communication.
But one thing I know for sure is that Apple has world class security engineers, and one area they work hard to secure is devices in BFU state.
On iPhones and iPads there are several technologies available for monitoring and filtering network traffic. Filter network traffic from the Apple Deployment Guide has an overview of the technologies and their trade-offs.
It’s not that simple. iOS has a really sophisticated system for deciding which things to keep in memory and which to evict, and it only does that when it needs more resources. Choosing which apps to kill is based on how recently an app was used, how much of share resources are in use, how often the app gets used, if it’s doing background processing, and other more subtle signals.
Usually if people notice apps being killed when in the background a lot it’s because one of the apps they’re switching to is using a lot of resources, which forces the eviction of other apps.
When you first boot up a device, most data on that device is encrypted. This is the Before First Unlock (BFU) state. In order to access any of that data, someone must enter the passcode. The Secure Enclave uses it to recreate the decryption keys that allow the device to access that encrypted data. Biometrics like Face ID and Touch ID won’t work: they can’t be used to recreate the encryption keys.
Once you unlock the device by entering the passcode the device generates the encryption keys and uses them to access the data. It keeps those keys in memory. If it didn’t, you’d have to enter your passcode over and over again in order to keep using your device. This is After First Unlock (AFU) state.
When you’re in AFU state and you lock your device, it doesn’t throw away the encryption keys. It just doesn’t permit you to access your device. This is when you can use biometrics to unlock it.
In some jurisdictions a judge can legally force someone to enter biometrics, but can’t force them give up their passcode. This legal distinction in the USA is that giving a passcode is “testimonial” because it requires giving over the contents of your mind, and forcing suspects to do that is not legal in the USA. Biometrics aren’t testimonial, and so someone can be forced to use them, similar to how arrested people are forced to give fingerprints.
Of course, in practical terms this is a meaningless distinction because both biometrics and a passcode can grant access to nearly all data on a device. So one interesting thing about BFU vs AFU is that BFU makes this legal hair-splitting moot: biometrics don’t work in BFU state.
But that’s not what the 404 Media articles are about. It’s more about the forensic tools that can sometimes extract data even from a locked device. A device in AFU state has lots of opportunities for attack compared to BFU. The encryption keys exist, some data is already decrypted in memory, the lightning port is active, it will connect to Wi-Fi networks, and so on. This constitutes a lot of attack surface that hackers could potentially exploit to pull data off the device. In BFU state, there’s very little data available and almost no attack surface. Automatically returning a device to BFU state improves resistance to hacking.
There’s a fatal flaw in the premise. It is impossible to fasten something to a cat.
Authorities with a warrant can drill into a safe to get to its contents. That’s legally distinct from forcing someone to unlock the safe by entering the combination. It takes some mental effort to enter a combination, so it counts as “testimony”, and in the USA people can’t be forced to testify against themselves.
The parallel in US law is that people can be forced to unlock a phone using biometrics, but they can’t be forced to unlock a phone by entering a passcode. The absurd part here is that the actions have the same effect, but one of them can be compelled and the other cannot.
You can’t fight brainwashing by providing more facts. It doesn’t work. Brainwashing gives the victim mechanisms to reject new facts that contradict the false beliefs. The false beliefs become a part of a person’s identity, so it’s tied into self esteem and confidence. So that’s how you have to approach it: find ways to challenge the false beliefs that don’t also challenge their sense of self. For adults this is very difficult.
But for children, it’s easier. During the teen years children are trying on identities like they’re trying on clothes. Give you child a look at a good, comfortable identity. It should make them confident, give them a community they feel comfortable in, and not make enemies of the ones they love.
I find that scientific skepticism does this by giving people the tools to think rationally about the world, spot ways that the world tries to deceive them, and giving an understanding of why those deceptions are effective.
Do you have any other resource hogs running in the background? Perhaps a poorly-coded VoIP or VPN extension could do that.
If you have access to a Mac you can use Console.app to see what log events there are about Voyager when you switch away. That would explain why it’s being killed.