Why? This seems like a smart anti-theft measure. (Bunch of iPhones in a radio silent environment together, maybe also not moving or detecting light.)
But how is a device in a faraday box receiving this signal and rebooting? And why do they need a signal when they could just use their own clocks and determine that it's been X days or weeks since last going online and reboot?
Doesn’t need to. Being in a Faraday box is a reasonable trigger for a single reboot. That said, the most incredulous part of this story is that iPhones can detect when they’re in a Faraday cage.
Lack of motion? The information the other phones provide are proximity (it’s unusual for people to pile their phones together), that the radios still work and possibly a timeline, e.g. if the other phone says “I’ve been in a suspicious state for two days,” the first phone can change its priors.
I'm even more confident that Apple hasn't spent the research hours required to do that reliably, then incorporate the electronics and software needed into off-the-shelf phones, all to protect criminals from having their phones hacked under very specific conditions. That seems like a huge money sink.
In a zero-signal environment? With other iPhones in very close proximity?
You can even measure your false positive rate by timing to first successful unlock. If it happens more than once, turn down the sensitivity on the feature (or turn it off completely).
(Were I designing this feature, I’d let phones in this state poll the other phones on how long they’ve been in it.)
Edit: I noticed it's "box" and not "cage" but I think the same what-if applies here.
They provide enough attenuation to keep phones off the cellular network and prevent GNSS from working, but not enough to prevent communication with nearby devices via Bluetooth or wifi.
A Faraday cage is an attenuator, which multiplicatively decreases signal strength by some constant (at least within a similar frequency band, which Bluetooth and 5G can be considered to be).
Unless the forensic lab has additional special shielding from cell towers, the received strength of both a reasonably close cell tower and a nearby Bluetooth transmitter would be pretty similar, so they'd both be attenuated similarly.
And while I don't expect stock iPhones to do anything like what's being suggested in the article, I could see custom software activating a "panic mode" based on observations that plausibly suggest a device being in such an environment.
I can say from experience that it is not.
> A Faraday cage is an attenuator, which multiplicatively decreases signal strength by some constant
It's not constant at all. The level of attenuation varies greatly based on frequency. For the Ramsey STE3000 I have here, it varies by 40dB or more at the frequencies at which I've tested it. The enclosure good for around -100dB at 700MHz, but only -60dB or so at 2.4GHz.
> (at least within a similar frequency band, which Bluetooth and 5G can be considered to be).
Even if you exclude mmWave and consider only the sub-6 bands, AT&T for example has LTE and 5G bands from 700MHz to 3700MHz. They're not similar at all. Worlds of difference in terms of propagation characteristics.
> the received strength of both a reasonably close cell tower and a nearby Bluetooth transmitter would be pretty similar
No, they wouldn't.
On my Pixel 8 Pro right now I'm seeing -93dBm from a tower about half a mile down the road (700MHz LTE), and -40dBm from the BLE radio in the HVAC controller on the wall of this room, about 8 or 10 feet away. That's a 53dB difference.
If I put my phone in the box, it attenuates the LTE downlink from down the street to well below the thermal noise floor. It cannot do the same for BLE; my phone can still talk to the HVAC controller from inside.
That's surprising, you'd think those boxes would be better at blocking signals since that's what they're designed to do.