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Comment by cherryteastain | Hacker News Reader

Easier solution: phone wipes itself if passcode is not entered every X hours

GrapheneOS already has an auto-reboot feature that can be set to time intervals ranging from 10 minutes to 72 hours. Rebooting puts the device back in before first unlock (BFU) state. This wipes all memory contents, including the encryption keys. Any unlock attempt will have to go through the secure element, which is basically impossible to tamper with (no successful attacks on the Titan M2 so far, or the Apple SEP for that matter), and includes substantial security mechanisms, such as throttling key derivations (through the Weaver API), or insider attack resistance (requiring user authentication before new firmware can be flashed to the secure element).

Leaked documents from mobile forensics companies, such as Cellebrite or XRY confirm this. It's impossible to crack a Pixel with GrapheneOS in BFU state. See https://grapheneos.social/@GrapheneOS/112462758257739953 and https://grapheneos.social/@GrapheneOS/112826067364945164

Deadmans-switch, nice. I always had a weird fascination for that kind of mechanism, because it inverts the whole situation. Where before you have to actively wipe a phone, now them taking your phone may be the mechanism that triggers the wipe.

Is it legally better? Absolutely. But all they have to do is say "they did this as a legal workaround for that" and you're no better off, at least not without spending the same amount on lawyers. You can't out-tech your way around a corrupt system, they will find a way to get you.

if you have it running constantly, i dont think that argument can be made

id expect that youd be ordered to retain the data though, if an investigation is being done

Any argument can be made, and accepted by a judge, in a sufficiently corrupt system. Like the parent said, you can't out tech this because logic ceases to be applied to laws. It instead become heads I win, tails you lose.

Yes sure, given a sufficiently corrupt system nothing helps. Even being innocent and revealing everything won't help.

But this stance amounts to giving up. Within the wiggle room a system gives us there are still ways to widen cracks or attach a lever, however small they may be.

There's a problem with that too: it would often force the owner of the phone to input the code when outside a secure environment, so a simple video surveillance could obtain the code.

GrapheneOS has a feature to scramble the locations of the numbers on the passcode unlock screen to prevent this exact problem

That can be helpful only if surveillance cannot film the screen directly, and surveillance relies on the position of the fingers. Given modern 4k cameras it's unlikely the latter can be done but not the former.

You can also use a privacy screen protector. Or use the two factor fingerprint unlock, which requires both a fingerprint and a PIN to unlock. And that's only after first unlock, so you can still use a separate, strong passphrase for BFU state.

Sure, a privacy screen makes things a bit more difficult for surveillance, because the camera would need a line of sight at a low angle, but once the code is known, the attacker can force a fingerprint and input the code.

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