Thread

Cops Can Bypass iPhone's Automatic Reboot to Get into Locked Phones

287 points · 226 comments · speckx

Cider9986 · 1790869574 · focus · HN ↗
For those who don't know, automatic reboot restarts your device if you haven't unlocked it in a set amount of time. Cellebrite and other digital forensics companies are able to get into AFU devices much more often. The automatic reboot feature was first introduced by GrapheneOS and was later added to iOS and stock Pixels.
GrapheneOS's default is 18 hours and it can be set to between 10 minutes and 72 hours. iPhones and Stock pixels have it non customizable at 72 hours.
On GrapheneOS, for privacy and convenience, it's best to use a long random passphrase [1] for your primary unlock and then a fingerprint with a second factor pin as the secondary unlock. You enter the passphrase every time the device restarts.
If you're encountering someone that's going to seize your phone, try to restart/shut it down yourself so you don't have to trust the AFU protections.
[1] <a href="https://strongphrase.net" rel="nofollow">https://strongphrase.net give memorable ones which is cool.
1. dylan604 · 1790871117 · focus · HN ↗
  > On GrapheneOS, for privacy and convenience, it's best to use a long random passphrase
  Why do you call out just one OS? It's a good idea for any OS.
  1. Cider9986 · 1790872104 · focus · HN ↗
    Yes, in fact on GrapheneOS it's less necessary and it's only necessary if you don't want to rely on the secure element rate limiting.
    GrapheneOS allows using a passphrase with more convenience because of the fingerprint plus second factor pin (I don't think you can just have a pin as a secondary unlock). You don't need to enter the passphrase every time you unlock with this setup, only when first starting up.
    The official opinion: <a href="https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=by%3Agrapheneos%20passphrase%20rate%20limit&sort=byDate&type=comment" rel="nofollow">https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
  2. rtkwe · 1790872445 · focus · HN ↗
    This seems specific to GrapheneOS (unique as far as I know though I'd be happy to learn otherwise) where you could set a very long first unlock passphrase and have a shorter less cumbersome fingerprint plus pin option for subsequent unlocks. I wouldn't want to have to enter a long passphrase every time I unlock but once a day isn't so bad.
    dylan604 · 1790872657 · focus · HN ↗
    I don't run GrapheneOS, but I have an >15 character passphrase that must be used before biometrics can be used after reboot. I haven't used a 4-digit pin since the option to not use it was available.
    rtkwe · 1790875270 · focus · HN ↗
    The specific extra that grapheneOS adds is that you can have a required Fingerprint + PIN with a shorter easier to enter pin while also having a long first unlock passcode. Only a first unlock passcode then biometrics is not secure in the US if your device is in the AFU/biometric-only (after first unlock) state because you can be easily and legally compelled to provide a biometric unlock.
    <a href="https://threecats.au/two-factor-pin-fingerprint-unlock-grapheneos" rel="nofollow">https://threecats.au/two-factor-pin-fingerprint-unlock-graph...
    dataflow · 1790872934 · focus · HN ↗
    The option was there in Cyanogenmod back during the OnePlus One days. It was such a step backwards when it was removed. You almost had to wonder if it was deliberately done at the request of some TLA to prevent users from using too strong of a password for decryption.
    rtkwe · 1790875317 · focus · HN ↗
    I doubt it, mostly because phones were a lot easier to crack back in those days already so I doubt a TLA needed to push for it to be removed.
  3. subscribed · 1790885659 · focus · HN ↗
    Because apart of the IOS, according to GrayKey and Cellebrite, GrapheneOS on Pixels is the only phone where it even makes sense (realistically).

Open on Hacker News to reply ↗

Unofficial Hacker News client; not affiliated with Y Combinator.