• GeneralPixel 7a

  • Locked out of phone with LONG enforced wait times between unlock attempts

Device: Pixel 7a
OS: Latest stable channel GrapheneOS
Steps to reprodue: In Settings > Display > Screen timeout, I tried changing the timeout from one value to another. This brings up a PIN entry. I typed in the wrong PIN too many times in a hurry and my phone locked me out.

Now I am unable to unlock my phone even though I am certain I am entering the correct PIN which I have no changed for over a year. The problem is that each time I try to unlock, the lockout timer increases and never resets, even when I don't make any attempts for 24 hours. The timer is now at 40,000 seconds! I don't believe stock Android's PIN entry delay goes that high. Is this limitless timer a GrapheneOS feature?

My questions are:

1) What could have happened? Why is the PIN I always use not working to unlock the phone after I wait for the phone to allow me to make another unlock attempt?

2) How long must I leave the phone untouched before the single attempt it gives me goes away and I am able to make several consecutive PIN attempts again?

3) Is there any upper limit on this timer? I thought 14000 seconds was excessive, now it's 40000 and keeps going up. I have data since my last backup that I really need on the phone. I can't factory reset it.

Thank you.

    duffieldde

    Sorry to hear about this issue.
    The delay maxes out at 1 attempt per day.

    From the GOS website:

    Standard delays for encryption key derivation enforced by the secure element:

    0 to 4 failed attempts: no delay
    5 failed attempts: 30 second delay
    6 to 9 failed attempts: no delay
    10 to 29 failed attempts: 30 second delay
    30 to 139 failed attempts: 30 × 2⌊(n - 30) ÷ 10⌋ where n is the number of failed attempts. This means the delay doubles after every 10 attempts. There's a 30 second delay after 30 failed attempts, 60s after 40, 120s after 50, 240s after 60, 480s after 70, 960s after 80, 1920s after 90, 3840s after 100, 7680s after 110, 15360s after 120 and 30720s after 130
    140 or more failed attempts: 86400 second delay (1 day)

    https://grapheneos.org/faq#encryption

        Maybe a kind mod could look at some kind of logs on your device?
        Can others reproduce this on other GOS phones?

        Otherwise, you may be out of luck.
        Hard to distinguish the situation described from that of an attacker trying to gain unauthorized access.

        I read through the link but it doesn't mention if like stock android, the timer will go away after a certain period of idle time, or if there will be a timer on there between single unlock attempts forever now.

        Another question I have is if I reboot the phone, it doesn't show the "wait 3 million seconds before trying again.." message until I try and enter a PIN. I am wondering is that first PIN entry attempt after restart a real attempt (it would unlock the phone if it were my real PIN) or if it's automatically rejected because of the timer which just doesn't show up until after I make one attempt?

        • de0u replied to this.

          duffieldde Is this limitless timer a GrapheneOS feature?

          I believe this is how the hardware works.

          duffieldde How long must I leave the phone untouched before the single attempt it gives me goes away and I am able to make several consecutive PIN attempts again?

          I believe it is necessary to successfully unlock the device before it will reset to normal behavior.

          duffieldde Why is the PIN I always use not working to unlock the phone after I wait for the phone to allow me to make another unlock attempt?

          If you have entered the same PIN 130 times, probably entering that one in again isn't going to work. But if you are sure there is nothing else you could enter, I would recommend writing it down on a piece of paper and then asking somebody to enter it for you.

          duffieldde What could have happened? Why is the PIN I always use not working to unlock the phone after I wait for the phone to allow me to make another unlock attempt?

          In theory the secure element (which is hardware) might have failed. This is genuinely quite unlikely, but in theory it can happen, just as any piece of hardware can fail.

                    de0u In theory the secure element (which is hardware) might have failed. This is genuinely quite unlikely, but in theory it can happen, just as any piece of hardware can fail.

                    If it's hardware failure and I bought a new phone, is it possible to somehow clone the image of the locked phone (in its encrypted state) onto the new one and try to unlock using the PIN? It's too hard to believe that I am forgetting the same PIN I've been entering for over a year. I wish grapheneos didn't have such a crazy upper limit on its attempt timer.

                        duffieldde If it's hardware failure and I bought a new phone, is it possible to somehow clone the image of the locked phone (in its encrypted state) onto the new one and try to unlock using the PIN?

                        For that I think it would be necessary to consult a professional data recovery service.

                        duffieldde I wish grapheneos didn't have such a crazy upper limit on its attempt timer.

                        I expect the current situation is very troublesome, but, again, I believe that the observed phenomenon is the way that Pixel hardware works, not a choice made by GrapheneOS.

                            Just type your pin very slowly being careful about every character you type, including the green check at the end. The only other thing that I can think of is a keyboard layout anomaly. Unlikely on the PIN screen, however, if the device is in a different region/language, you might be typing the wrong keys

                            duffieldde Another question I have is if I reboot the phone, it doesn't show the "wait 3 million seconds before trying again.." message until I try and enter a PIN. I am wondering is that first PIN entry attempt after restart a real attempt (it would unlock the phone if it were my real PIN) or if it's automatically rejected because of the timer which just doesn't show up until after I make one attempt?

                            I suspect that first attempt must be rejected (otherwise no delay longer than a minute or two would be meaningful). Whether or not that rejection counts toward increasing the delay, I don't know.

                              duffieldde No, this is likely impossible because you would need the secure elements keys from the original device.

                                zzz These throttling times were fully accurate but we likely need to update it for the newer releases of the firmware.

                                • zzz likes this.

                                  duffieldde its not possible to copy device data or decrypt it outside of the pin method on the original phone, sorry.

                                  Type it slowly, is my best advice, when you get the option to unlock it again.

                                    Next time before entering your password, you can try to swipe up from the bottom of your screen instead of tapping the lock icon to enter the password. There's a UI bug introduced recently.

                                      The throttling times don't max out at 24 hours. I'm now up to over 133,000 seconds which is 36 hours between attempts.

                                      Upstate1618

                                      Thanks Upstate1618 I will try that next time it lets me enter another PIN which will be about 30 hours. I hope the problem is this UI bug you mentioned. That makes more sense than me forgetting my PIN.

                                        duffieldde do have your data backed up in any way? Factory wipe will enable you to start afresh and use your device again.