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Comment by seiji | Hacker News Reader

Have there been any cases of police illegally forcing fingerprint unlock against a person's express consent?

Finger unlock is nice when you're in a non-hostile environment, but now with a 100ms finger brush, the entire phone opens up wide and says "take all my data!"

I wish iPhones had a feature like "if dropped on the floor (or after any 'significant' impact), remove session key to disable finger print auth and require password again." Then when you gotta cheese it, you just throw and go.

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Why would they have to force that? It's not too hard to manufacture something that will bypass the fingerprint unlock using rubber cement or silicon gel, especially for an organization that is one of the few expected to have your fingerprints on file (at least in the scenario we are describing, where you're already in custody).

Also: finger unlock only works after a password has been entered once (to generate the "finger unlock" key). Copying fingerprints or compelling finger access is moot if the device dumps the finger unlock key (as is done after 48 hours of no finger auth or after 5 (?) failed finger auth attempts).

But, trying to revoke the finger auth key in an emergency (less than 5 seconds) is difficult. Your only option is to try and quickly power off the device, but you're at the mercy of the "press and hold sleep/wake button for 5 seconds, then slide to turn off" delay timer.

Or quickly chew off your fingers.

Android dumps all "smart unlock" options when you press and hold (1 second) on the 'slide to unlock' on screen button and forces passcode/password/pin from that point on. I practice doing this so it's not foreign to me if I ever find myself in a dodgy scenario.

Really? How exactly do you do that? I've got the Xperia Z5, where the wake/sleep button is also a fingerprint scanner, so I can't exactly hold that without unlocking the phone, and holding the little padlock icon on the screen doesn't do anything.

The on screen slide to unlock button. Works perfectly on my Z3c and I'm hoping to not lose such a nice feature if I upgrade to a Z5c but it sounds like I might :(

https://vid.me/Ns12

Alright, I just tried that, and I do get the "Device will remain locked until you manually unlock it" but the fingerprint scanner still works fine. The only time I've seen it forcing me to use the pin was when it couldn't scan my finger 3 times in the row(which doesn't really happen, the sensor in that thing is really accurate(or really forgiving)).

That's a shame :( It'll be interesting to see if Marshmallow with its official fingerprint API changes the behaviour as handset manufacturers are implementing fingerprint support themselves in Lollipop (and so its going to be a bit all over the place).

If you hold the power and face buttons for about 10 seconds the phone will turn off. Takes two hands though.

That or hold the power and home buttons for 10 seconds. Can be done in your pocket.

I continue to find it improbable that even a recorded fingerprint that's not a high resolution scan would suffice for touchid spoofing.

Of course if ever you have an opportunity in an arrest you should shut down the iPhone... Unlock would require passcode.

I wasn't trying to imply it was theoretically possibly, I was trying to state it can be, and has been, done[1].

1: https://securityledger.com/2013/09/iphone-touchid-falls-to-w...

They digitally scanned my finger print for my EU passport. I wouldn't doubt they could print it and use it to unlock a device. At the speed and multitude of angles fingerprint sensors seem to work, I'm sure it forgives a lot of error/blurriness for the sake of user friendliness.

I've seen videos where somebody tested a gun safe with a similar locking device and it proved to be pretty resilient to that type of attack. I think they finally got it open using a cast mould of his print but it required having physical access to the finger in question.

500 DPI amounts to less than 200x200 pixels in a circle if I got the numbers right. A camera can't get that resolution from your fingerprints?

Fingerprint unlock allows 5 fingers on file. Maybe if you attempted an unlock with a different finger (pinky, say), it locked out that method until you'd used your passcode instead?

Similar to the idea of having a second PIN on your credit card that allows access but indicates acting-under-duress to the bank.

Yeah, there are a lot of clever ways it could be done, but with completely closed platforms we are just at the mercy of our proprietarily coded overlords.

Can appreciate that, but I do think Apple are showing genuine signs of caring about users in this area.

The other ones the code is just there to take it, code review it and use any loopholes.

> Similar to the idea of having a second PIN on your credit card that allows access but indicates acting-under-duress to the bank.

Sounds like you are alluding to being able to use a reverse version of your PIN on an ATM when in duress?

It's a trope [0].

[0] http://www.snopes.com/business/bank/pinalert.asp

    > It's a trope

If it's debuked on Snopes, it's an urban legend or a myth. Trope means something different.

Which is why I termed it an "idea".

When police departments seize electronics, like phones or computers, I thought it was standard for them to clone any hard drives so that they don't lose any data to similar techniques.

Is there a reason that they couldn't employ this countermeasure for your suggested security?

It is possible to secure devices in ways that even the correct passcode or fingerprint will only work with a specific chipset/decryption module. Some flash storage is also only readable after an unlock code has been transmitted.

I think they can legally fingerprint you and use that to unlock the phone but they cannot force you to reveal your password because you would be forced to incriminate yourself. (If you did in fact commit a crime)

This is just more evidence supporting the claim, which has already been persuasively argued elsewhere, [0] that fingerprints are usernames, not passwords.

[0] http://blog.dustinkirkland.com/2013/10/fingerprints-are-user...

It's way more nuanced than that. Fingerprints are certainly way more like a password versus an adversary like a crazy girlfriend who gets your phone, but closer to a username against a very formidable adversary. Certainly not equal though.

So more like a token?

How often does that happen outside of TV? In most cases where you have legal protection which actually works, you would also be able to power down the phone. In most of the other scenarios, most people are going to unlock it anyway under the threat of a beating or threats that non-cooperation will result in heavy/fabricated charges.

> threats that non-cooperation will result in heavy/fabricated charges.

Being DA 101

Or you could just turn since first authentication after booting requires a passcode.

Situation: you're arrested/captured/etc. All they have to do is, on a new 6S phone, touch your finger to the sensor for 1/10th of a second.

There's no emergency evac situation. You either have basically no protection from hostile action or you avoid finger auth.

If there's a reasonable risk that this situation might ever apply to you, then just don't turn on TouchID and always use the passcode.

If you're an international spy or something, maybe don't store your top secret data on consumer-grade electronics.

Or someone you sleep with wants to read your texts and all it takes is a light tap of a finger while you're unconscious to open your phone completely.

as far as "international spy," we have national level security directors storing secrets in AOL accounts. We can't protect people from themselves, so we have to make systems better for everybody.

I think it's to be determined if that would be an illegal search.

If they do stuff like that, they will probably deny that they did it. Having had access to your phone, they can look for information that can be used to find other leads, that will be strong enough for a court order.

you tap different finger five times. Boom, touch id is off, you need to enter passcode.

I just like the idea of training it to learn different fingers... you know what I mean.

just like it needs passcodes that do that same, if not more. a passcode to let you in, one to CALL the cops, and another to thwart them

There's a setting, in the most recent iOS at least, you can enable where 10 failed fingerprint attempts will trigger the phone to wipe itself.

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