
Using Face ID to unlock brother’s iPhone X after entering PIN - codesternews
https://www.reddit.com/r/iphone/comments/7anj9f/iphonex_face_id_fail/
======
gtsteve
It would appear that if you enter the PIN, it rescans your face; presumably as
their faces are rather similar it can be trained to accept two faces. The OP
wrote an extra comment explaining this:

[https://www.reddit.com/r/iphone/comments/7anj9f/iphonex_face...](https://www.reddit.com/r/iphone/comments/7anj9f/iphonex_face_id_fail/dpcih16/)

Edit: Oh, it seems they posted a follow-up video which explains the behaviour:

[https://www.reddit.com/r/iphone/comments/7atwap/update_iphon...](https://www.reddit.com/r/iphone/comments/7atwap/update_iphonex_face_id_fail/)

It hasn't stopped news sites from reporting this however.

~~~
Geee
It doesn't actually matter if it's a bug or a feature. If you share your
passcode with someone, they might as well get in with their face. It's not a
security risk.

~~~
viraptor
Until you change your passcode to lock them out and they will have access via
faceid. If they have an irrevocable access you don't know about, it's a
security issue.

~~~
ballenf
I don't think this is going to be an issue after even a few days' usage and
training, but it's too soon to tell. As the brothers point out this seemed to
only work on newly reset Face ID phones.

What bothers me more about all this is what a pain it is to pass a phone to my
spouse now since you can't intentionally train more than one face. Wife and I
routinely use each others phones and while we know the PIN codes, it sure is
nice to avoid that hassle.

------
tribby
this appears to be a trick of sorts. according to a comment by one of the
brothers, faceid only acknowledged the new user after the phone had been
unlocked via PIN while looking at it. that sounds a bit like an intentional
feature for training the facial recognition?

~~~
lttlrck
What happens when an untrusted person that uses your PIN on a regular basis
for legitimate reasons becomes untrusted? Now you need to reset your PIN and
retrain FaceID? I hope IOS gives a warning when changing the PIN that if you
think FaceID has been compromised to retrain FaceID. edit: because the idea
that FaceID could be compromised like this is non-obvious

~~~
skywhopper
Sounds like it will only happen if the faces are similar. So if the threshold
for matching is 95% match to the internal model, but the faces are 90%
similar, and then the new face enters the correct PIN, then the new face will
be used to tweak the model, which will move the error to inbetween the
features of both. So if their faces are similar to within twice the margin-of-
error of the detection algorithm, then you can probably get this effect.

All that said "an untrusted person that uses your PIN" knows your PIN... so
they are a trusted person as far as the OS is concerned. There's nothing you
can do with FaceID/TouchID that you can't do with the PIN. All FaceID/TouchID
do is decrypt the PIN from the secure enclave. So if you've shared your PIN
with them, then this is a weird thing, but not actually a security violation.

~~~
dTal
The difference is that it's easy to change a PIN, but hard to retrain FaceID.
So sharing a PIN is reasonable in the knowledge that it can be changed, but
you might not be aware that it has more ramifications under opaque and unclear
circumstances.

~~~
zwily
Retraining FaceID takes about 20 seconds. How is that hard?

~~~
ProblemFactory
The hardest part might be noticing in the first place that your FaceID model
has drifted away from only your face.

~~~
dpkonofa
That's the thing, though... it would only drift from your face if the face it
was drifting too looked similarly enough to your own.

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ballenf
Thinking about unlocking as an application of the Birthday Problem (or
Paradox), can someone with better math skills than me calculate the # of
iPhone X users in a room necessary to get to 50% chance that someone can
unlock someone else's phone? This would ignore the problem in the article and
assume 1 in 1e6 odds.

[https://en.wikipedia.org/wiki/Birthday_problem](https://en.wikipedia.org/wiki/Birthday_problem)

~~~
crindy
This seems like a silly way to think about FaceID. You’d need 1000+ people to
_all_ try their faces on each other’s 1000+ phones to get the 50% chance of
unlocking. That’s not the scenario biometric authentication is built for,
which is why the phone would require a password after 5 failed attempts.

~~~
mjevans
The problem with that is the ease with which anyone can compare their input to
the 'key'; externally.

You could very quickly rule out 95% of the field with little effort, and
people already do things like say "you look so much like X": we have a short
list of collisions already.

~~~
katastic
Exactly. I'm more worried about if someone can make a mask of someone's face
(or even a print out) and get it to work.

But at least it's not like people have pictures of their faces plastered
across every social network...

... crap.

~~~
gnicholas
As others have said, those who have tried masks haven't worked. But I wonder
if normal masks have different heat signatures than real faces, which an IR
array can detect. It's possible that something as simple as standard mask +
heat would fool the system. Hopefully not!

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alkonaut
Is the feature that it will "re-train" on a new but similar face once
unlocked, and this is in order to handle normal slow change of people's faces?

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hajile
Facebook says one in a million people will match (vs one in 50k for
fingerprints). I'd guess that close family generally have a better shot of
being that face match compared to a complete stranger (unlike fingerprints
which don't seem to have familial features).

~~~
addicted
That’s the issue I’ve had with Apple’s claims about FaceID being X times more
secure than TouchID.

Your facial features are very likely to be similar to people who live around
you. I don’t believe this is true of fingerprints.

So it seems it’s far more likely that the 1 in million chance of an overlap
will be around your phone than the 1 in 50000 chance in case of TouchID.

~~~
weego
It's also far more likely that those people do not pose a genuine malicious
threat to your data and security

~~~
jonlucc
I think parents who have had their kids purchase things from the app store
without their approval might disagree.

~~~
tedunangst
Does FaceID recognize children as their parents?

~~~
dpkonofa
Only if the parents have given their child the PIN and they also look similar
enough to trigger against the existing facial model.

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PebblesHD
On a related note, I tried face ID with my identical twin’s iphone X, and sure
enough it lets me in pretty much every time without any trickery with the PIN.
It’s made me quite uncomfortable with the security it offers as we aren’t so
identical as to be mistaken frequently, yet the phone unlocks almost every
time...

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zitterbewegung
I have a twin and when we tried the Face ID demo with my face loaded in my
brother could have it say 'face recognised'.

This would be conveinent for me because since we both commute to work I have
to queue up a playlist or read his messages / email. But, I believe this was a
design compromise that was pointed out in the product launch event.

~~~
alkonaut
If you have an identical twin you could have fooled a DNA test. I don't think
it's a reasonable bar for an unlock-convenience to be more secure than that.

~~~
mikeash
I agree, but to be fair, identical twins will be read as different people with
a fingerprint scanner.

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moogly
I'm more concerned about the fact that it seems you have to do a pointless
finger swipe to get away from the lock screen even though the phone is
actually unlocked. I'd be furious.

~~~
Geee
What if you want to check the time or notifications?

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coldtea
> _IPhoneX Face ID fail?_

Obviously not, since apart from the hair (or lack thereof), the two brothers
look almost identical.

Apple itself said, and not just in some support document, but in the keynote,
that it will fail if you have an "evil twin" or, well, an actual twin.

~~~
the_common_man
To me all arabs/chinese/Japanese look the same as well. I asked an Indian
friend and he said they are not similar.

~~~
coldtea
I don't have difficulty telling Indians (or Chinese etc. for that matter)
apart -- I'm also not American myself, and have worked in Asian countries.

They just look very similar to me -- and apparently to Face ID too, and after
all, they _are_ siblings.

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dmitriid
This was addressed in the keynote in no uncertain terms. Starting at 12:12
here: [https://youtu.be/eRvBU_tKGjE](https://youtu.be/eRvBU_tKGjE)

Why this is such news to some is a mystery to me

~~~
robert_foss
Because of the reasonable expectation of security?

~~~
dmitriid
Because people are fools and can’t remember what the company specifically
addressed in their own keynote on the actual tech barely a month after said
keynote

------
joering2
Said that 53 days ago...

[https://news.ycombinator.com/item?id=15232739](https://news.ycombinator.com/item?id=15232739)

What was Apple thinking??

~~~
coldtea
That since this requires both a PIN and an unlikely similar face (brothers
that look more like twins) it's a moot point?

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sandworm101
Free legal advice: dont lock your phone using biometrics like face id. A
password is subject to constitutional protections. Your face is not.

Free first aid advice from a lawyer in the armed forces: good luck unlocking
your phone after a head/face injury. Hospital will be so much more fun with
your phone locked in emergency mode because it wont recognize your swollen
face.

~~~
BoorishBears
You realize you can still use your pin to open it it right?

And you can disable the biometrics with a simple key combination.

~~~
sandworm101
And when the police sieze your phone and use your face to unlock it before you
can disable it? Ever wonder why apple allows for five tries with the
fingerprint reader? They can guess whether you are right handed. After that
there are only five digits to test.

As for if injured: go with something like a pin or pattern that doesn't
require any paticular body part. My fingurprints never scan properly after
swimming or rock climbing.

~~~
sdtransier
Apple added an Emergency mode in iOS 11 that’s accessible by clicking the
sleep/wake button five times. It also disables Touch ID/Face ID and requires
the passcode after that. So if you think your phone will be seized, it’s a
pretty quick way to disable everything but the passcode.

[https://www.macrumors.com/2017/08/17/ios-11-emergency-sos-
di...](https://www.macrumors.com/2017/08/17/ios-11-emergency-sos-disables-
touch-id/)

~~~
mschuster91
> So if you think your phone will be seized, it’s a pretty quick way to
> disable everything but the passcode.

Good luck if the cops assault you from behind or early in the morning...

~~~
BoorishBears
By that logic they can also just assult you while the phone is unlocked...
which is probably many more times than early in morning.

------
hungerstrike
Face ID is going to be a monumental failure. It's going to annoy everybody who
likes things to happen fast all the time because Face ID will definitely cause
a delay and frustrate every user at some point.

Here are quotes from 2 of the very first reviews of this device:

"I will admit I have not tried Face ID yet, but it's hard to imagine a facial
recognition system that solves the problem of having to carefully aim a phone
at your face." \- [https://arstechnica.com/gadgets/2017/09/face-id-on-the-
iphon...](https://arstechnica.com/gadgets/2017/09/face-id-on-the-iphone-x-is-
probably-going-to-suck/) "[Face ID] worked the vast majority of times I tried
it"... (NOTE: Not ALL the time) - and "...it’s definitely faster than the
first generation of Touch ID, though perhaps slightly slower than the second
gen." \- [https://techcrunch.com/2017/10/31/review-the-iphone-x-
goes-t...](https://techcrunch.com/2017/10/31/review-the-iphone-x-goes-to-
disneyland/)

And while everyone is holding their breath to see if Face ID works, I can see
a bigger problem - The lack of a home button is probably the worst design
decision. They should have gone with dedicated virtual home button or better
yet, stick with the iPhone 7 style home button. iOS 10 and 11 already has too
many problems distinguishing between "global gestures" and "application
gestures". Half the time when I start scrolling near the bottom of the screen
the control center shows up. I'm looking forward to Apple's time being over.
They are already obviously struggling to keep their market share because they
can't come up with innovations that people actually want.

~~~
54mf
"It's going to annoy everybody who likes things to happen fast all the time
because Face ID will definitely cause a delay and frustrate every user at some
point."

It doesn't. FaceID is faster and as reliable as TouchID was for me. Not to
mention, with winter coming, have you tried using TouchID with cold fingers?
Spoiler alert: it mostly fails.

"The lack of a home button is probably the worst design decision."

Disagree. App switching is faster than ever, the new gestures stick after ~30
minutes of use, unlocking my phone takes less time.

"Half the time when I start scrolling near the bottom of the screen the
control center shows up."

The control center isn't accessed by swiping up on iPhone X, it's accessed by
swiping down from the upper right "ear" of the screen. So this is a non-
starter.

Source: I've been using my iPhone X with FaceID since Friday afternoon, iPhone
user since 2008.

~~~
ReverseCold
Every time anyone says Apple is going downhill, they have their best quarter
ever.

