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Comment by r00fus | Hacker News Reader

If they have access to a live finger for the TouchID, sure they can bypass - but they could do that with the $5 guaranteed coercion method as well [1].

Copying a good fingerprint from a dead finger or a randomly placed print is not easy [2]. It's hard, doable but you get 5 tries so if you screw up, you have thrown away all the hard work of the print transfer.

All bets are off if the iPhone is power-cycled. Best bet if you're pulled over by authorities or at a security checkpoint is to turn off your iPhone (and have a strong alphanumeric passcode).

[1] https://xkcd.com/538/ [2] https://blog.lookout.com/blog/2013/09/23/why-i-hacked-apples...

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> All bets are off if the iPhone is power-cycled. Best bet if you're pulled over by authorities or at a security checkpoint is to turn off your iPhone (and have a strong alphanumeric passcode).

Excellent advice. Even better, if you're about to pass through US customs and border patrol, backup the phone first, wipe, and restore on the other side. Of course, this depends on your level of paranoia. I am paranoid.

If you're paranoid, making a complete copy of all your secrets on some remote Apple or Google "cloud" where the government can get at it trivially is the exact opposite of what you want to be doing.

If you're paranoid, you don't have a cell phone.

Or you have several, and send them on trips without you, etc.

Well, yeah, if you back it up with a 3rd party backup tool, you are trusting the 3rd party.

I recommend you make a backup to your laptop, which you then encrypt manually. That way the trust model is: you trust yourself. Then you can do whatever you want with the encrypted file. Apple's iCloud is perfectly fine at this point.

The real challenge is to find a way to restore that backup, because you have to be on a computer you trust. If you decrypt the backup on a "loaner" laptop, your security is broken.

If you decrypt the backup on your personal laptop but the laptop has a hidden keylogger installed by the TSA or TAO, your security is broken.

It would be necessary to backup the phone on the _phone_ _itself_. Then manually encrypt the file (easy to do). Then upload to iCloud. At this time, no such app exists for iOS.

Since you plan to restore the backup to the phone anyway, it's no problem to decrypt a file on the phone before using it for the restore.

> I recommend you make a backup to your laptop, which you then encrypt manually.

You mean your laptop that was manufactured by a 3rd party, with a network card that was manufactured by a 3rd party? And you're using encryption software that, even if it's open source, you probably aren't qualified to code review. I'm not downplaying the benefit of being careful, but unfortunately you can keep doing that pretty much forever.

All laptops and cameras entering the US are subject to search and seizure.

Well you can make an encrypted Backup via iTunes (that would involve firing up iTunes though shudders)

There's a reason Google decided to encrypt all communication between machines inside their datacenters.

Are you sure it's not just communication between data centres?

Probably not. FB is doing the same thing. In most cases your app or service does not actually know if the remote service it is talking to is local or in another DC. Yes, you can find out if you need to, but that requires contacting another service and introduces some delay and latency. Use a service router to try to keep the calls local to a rack or a DC, but you know that if there are problems with local cells you might get routed across the country so start with the assumption that _all_ connections get encrypted even if the connection is to localhost.

backup ==> zip/rar => encrypt with pgp or whatever => split => upload various parts to different cloud storage providers => wipe device => pass checkpoint => download => combine => decrpy => uncompress => restore.

its not trivial, but its sure easy to do in this day and age.

What data is likely on someone's phone that is not also in the cloud one way or another?

I wonder this too. The only personal data on my phone are my text and email messages. I'm not sure how other data would get onto the phone.

Wiping the phone doesn't help you. Using the strong password renders the information inaccessible, at least as inaccessible as your phone backup is. Touch ID isn't re-enabled until the phone's passcode is used. Presumably if the authorities have access to your phone's memory they also have access to your laptops, and neither will do them any damn good.

And it's paranoia if there's a legitimate threat, that's just called due diligence. ;)

> Touch ID isn't re-enabled until the phone's passcode is used.

Do the docs confirm that there is no way around this? I'd guess generating the encryption key requires the passcode, which is discarded immediately, and Touch ID can only "unlock" a temporarily re-encrypted version which never leaves ephemeral storage?

From the iOS Security Guide - How Touch ID unlocks an iOS device;

  If Touch ID is turned off, when a device locks, the keys for Data Protection class
  Complete, which are held in the Secure Enclave, are discarded. The files and keychain
  items in that class are inaccessible until the user unlocks the device by entering his
  or her passcode.

  With Touch ID turned on, the keys are not discarded when the device locks; instead,
  they’re wrapped with a key that is given to the Touch ID subsystem inside the Secure
  Enclave. When a user attempts to unlock the device, if Touch ID recognizes the user’s
  fingerprint, it provides the key for unwrapping the Data Protection keys, and the
  device is unlocked. This process provides additional protection by requiring the
  Data Protection and Touch ID subsystems to cooperate in order to unlock the device.
  The keys needed for Touch ID to unlock the device are lost if the device reboots
  and are discarded by the Secure Enclave after 48 hours or five failed Touch ID
  recognition attempts.

TouchID I believe unlocks the passcode so the phone can use it to login, but TouchID itself is not enabled until you enter it once, presumably because it isn't actually stored on the device in a readable way.

OK, I guess the effect is the same (as long as the passcode isn't recoverable until after startup). Thanks.

Could the "code equivalent" of your fingerprint be stolen by a rogue app if it's allowed to read it? I don't have a touchId phone but have wondered what would happen if your "print" is stolen -- passwords can at least be changed.

Speaking as an App Developer, we cannot touch stuff like that. We're allowed to ask Touch ID to verify things and process the results, but we don't actually get to use the Touch ID system. It's similar to how the shared keychain is used: We can ask iOS to do things, but then must handle any one of many possible answers. We don't actually see your fingerprint in any way.

Now Cydia and 3rd party stuff? I have no clue.

iOS itself does not see fingerprints, it refers to SE.

Wouldn't surprise me if true, iOS as a whole is built in a very modular fashion when it comes to the different components of the OS and developers only get access to what Apple deems us worthy of, hehe. Not that I want access to Touch ID, I much prefer to not have access to that...

Can non-US citizens be coerced into giving up their passcode?

Depends on if they're at a border crossing or in the interior of the country. Laws apply to citizens and non-citizens alike. If you haven't been admitted to the country, about the most they can do is turn you away at the border checkpoint and put you on the next flight back to your home country.

and if you're a citizen of the country you're trying to enter...

Then the TSA drops a paper clip while you bend over and pick it up

No, at least, not by the DOJ, and not for any use in a court of law.

We wrote about this in our border search guide and concluded that there is a risk of being refused admission to the U.S. in this case (in the border search context) because the CBP agents performing the inspection have extremely broad discretion on "admissibility" of non-citizens and non-permanent residents, and refusing to cooperate with what they see as a part of the inspection could be something that would lead them to turn someone away. (However, this is still not quite the same as forcing someone to answer in the sense that they don't obviously get to impose penal sanctions on people for saying no.)

One reason I'll never visit the states.

If I absolutely had to I just wouldn't take a phone/laptop with me.

" they don't obviously get to impose penal sanctions on people for saying no"

I wonder if there is any negative effects associated with being refused entry by a CBP? Could it be the case that if you are refused entry once, that in the future they will be more likely to refuse you entry? If so, that's a fairly significant penalty/power that the CBP person has.

> I wonder if there is any negative effects associated with being refused entry by a CBP? Could it be the case that if you are refused entry once, that in the future they will be more likely to refuse you entry? If so, that's a fairly significant penalty/power that the CBP person has.

Yes, some categories of non-citizen visitors (I don't remember which) are asked on the form if they have ever been refused entry to the U.S. (and are required to answer yes or no). If they're using the same passport number as before, CBP likely also has access to a computerized record of the previous interaction.

Plenty of countries will ask if you've ever been refused entry to any country. And you're also generally automatically excluded from any Visa Waiver Programme from then on too. So it's a major issue.

> If they're using the same passport number as before, CBP likely also has access to a computerized record of the previous interaction.

(They might also be able to search their database by biographical details such as date of birth, so getting a different passport may not prevent them from guessing that you're the same person.)

It is not a good bet if you're pulled over by the authorities to be doing something with your hands that they can't reliably identify as different from preparing a weapon. Particularly if not white.

This would prevent people from recording police abuse ...

Power-cycling can be done relatively quickly - in 10sec with two fingers (no swipe), or 5 sec + swipe if you only have one hand available.

> "Copying a good fingerprint from a dead finger or a randomly placed print is not easy [2]. It's hard, doable but you get 5 tries so if you screw up, you have thrown away all the hard work of the print transfer."

You get plenty of tries to perfect the technique, before using it on the actual device.

You acquire identical hardware and "dead finger countermeasures" (does the iphone employ any? Some readers look for pulses and whatnot, I don't know if the iphone does). You then practice reading the fingerprint on that hardware until you are able to reliably get a clean print and bypass any countermeasures. Only then do you try using the finger on the target phone.

You might still fuck it up, and you only get 5 chances on the target hardware. But with practice on the right hardware, I see no reason why you couldn't get it.

There's also a 48 hour window and touch ID doesn't work initially after booting.

https://support.apple.com/en-us/HT204587

Great design.

Not only the amount of work, technology and thought that have gone into this, but also how well this has been implemented is mind-blowing.

It really shows the staggering difference between having a Samsung phone with fingerprint security versus an iPhone.

Is it only five fails on TouchID to delete data? I don't have the option to delete the data enabled on my iPhone... but it often takes more than five tries to just get it to work on my finger that is legitimately registered in touchID.

After five failures the you cannot use Touch ID to unlock and will instead need the passcode to access the phone again. This means that any approach to fooling the fingerprint reader will need to be done within five tries.

No, it's five fails before Touch ID stops working until after a passcode is entered again.

You should overtrain your TouchID: http://www.imore.com/touch-id-not-working-you-heres-fix

Given the 6 tries, is there any benefit to a strong password?

It's my understanding that the current battle is about the request to bypass the retry cap.

  All bets are off if the iPhone is power-cycled.

Except, you don't have explicit control over the iPhone's battery, so how do you know if the power is actually cycled?

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