
Researchers Created Fake 'Master' Fingerprints to Unlock Smartphones - known
https://motherboard.vice.com/en_us/article/bjenyd/researchers-created-fake-master-fingerprints-to-unlock-smartphones
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fpgaminer
Really interesting work. Snippet from the paper's summary for the lazy:

> The proposed method [...] is based on training a Generative Adversarial
> Network on a set of real fingerprint images. Stochastic search [...] is then
> used to search for latent input variables to the generator network that can
> maximize the number of impostor matches as assessed by a fingerprint
> recognizer.

So I hadn't heard about "MasterPrints"; the idea that there are fingerprints
(synthetic or otherwise) that just happen to have a lot of false matches.
That's not intuitive, at least for people like me who know nothing about
fingerprint matching algorithms.

Also an interesting application of GANs.

As noted, this research was done in software. I'm not sure if you can apply
something similar to physical sensor hardware. Especially since you only get a
couple attempts on real hardware before most phones lock out to your pin code.
And attacking real hardware would require either A) some kind of physical
fingerprint simulator to interface with the sensor or B) opening the phone to
get direct access to the I/O (which might then fall afoul of tamper detection,
if such a thing exists on phones). But it's cool research regardless.

Now I'm curious if similar techniques can be applied to faces. Are there
"MasterFaces"? Do some people have faces that generate more false positives
than others?

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pbhjpbhj
Presumably an eigen-face acts as a master-face of sorts?

~~~
NarcolepticFrog
Why would it? Eigen-faces tend to not even look like faces (which makes sense,
given that the goal is to represent a collection of real faces as linear
combinations of the orthogonal eigen-faces). One possibility would be to
generate random faces as random linear combinations of the eigen-face basis,
but this type of attack could be thwarted by rate limiting.

A real "master face" would be a face that looks like many people, and it seems
like you could try to obtain faces like that by playing a two-player game
between a recognizer and a face generator (as is done when training GANs).

~~~
c3534l
The images that screw up image recognition systems to get very high confidence
of very wrong classifications don't look like the thing they're mistaken for
at all. All the GANs I've seen produce what looks like colorful static to a
human eye. I'm not sure where you're getting the info that it would look like
an average face because I've never seen ML systems defeated with GANs like
that.

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ixtli
> Biometric IDs seem to be about as close to a perfect identification system
> as you can get.

This seems a massive assertion that’s not qualified at all in the article. It
was my understanding that biometrics in consumer hardware have always been
easily circumvented and are largely about convenience.

~~~
chongli
And honestly they're not that convenient. The Touch ID in my iPhone 8+ rejects
my print at least a dozen times a day. On some days it rejects it many times
in a row, forcing me to key in my unlock code.

Research like this, while ostensibly threatening an increase in false
positives (due to unauthorized use of fake prints), will in all likelihood
cause vendors to tighten the confidence interval, leading to greatly increased
false negatives. If my print is recognized less than half the time I'm just
going to disable the feature.

~~~
Angostura
Sounds like you should maybe retrain it. My iPhone 6, which has the older
sensor tech is fine: unless my hands are wet

~~~
mauriciob
This is the problem I have. If there’s just a little sweat on my finger, it
stops working.

~~~
tomalpha
Just for another piece of anecdata: mine used not to work if my finger was too
_dry_... I resorted to everything up to and including licking the finger and
retrying. Which, oddly, usually worked.

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coldcode
Not enough detail in the article. There is no discussion of what sensors were
used to "fool". Now everyone will assume it works on all actual devices using
fingerprints, yet there is no information to support that conclusion. If this
technique were applied to actual devices (with fingerprints not included in
the study) and it worked reliably, then this would be a meaningful study.

~~~
brian_herman
Here is the paper on arxiv:
[https://arxiv.org/abs/1705.07386](https://arxiv.org/abs/1705.07386)

~~~
kbumsik
So the experiment is done against VeriFinger [1], which seems like a software
solution for fingerprint identification. No actual device is used in the
paper, and I assume it is less sophisticated then Apple Touch ID or something.

[1]
[https://www.neurotechnology.com/verifinger.html](https://www.neurotechnology.com/verifinger.html)

~~~
ChristianBundy
> I assume it is less sophisticated then Apple Touch ID or something

Why?

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kbumsik
Maybe "less sophisticated" is overreaction but I thought that because there is
no dedicated hardware setup that can contribute to better accurarcy/security.

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soohyung
Original paper can be found here
[https://arxiv.org/abs/1705.07386](https://arxiv.org/abs/1705.07386)

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exabrial
I'm fine with "casual" security like my fingerprints for my phone and laptop
as primary authentication. It annoys me I have to enter a password first from
a user experience perspective.

There's definitely need for very hardened phones from physical attack
(journalists, canaries, whistleblowers, etc). I'm just not that important so I
wish I could choose my security level.

~~~
rvense
It's still very important to know that these owls aren't necessarily what they
seem. People will hear the phrase "fingerprint recognition" and think "Oh
that's clever because I'm the only one with these fingerprints!" and assume
that that makes it secure. But of course the reality is more complicated than
that, and personally I prefer a passphrase because I understand much better
how that works and what the potential points of failure are.

~~~
exabrial
Exactly, actually. My point being that swiping my fingerprints is a big enough
pain in the butt for relatively low value of return, and it doesn't scale
across users.

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rvense
Personally, I'm not at all surprised something like this can exist. We know
object-recognizing neural networks have issues like this, why shouldn't
fingerprint readers? It seems obvious that advanced, semi-opaque maths like
what's in a fingerprint reader will have strange and unpredictable failure
modes.

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nneonneo
Speaking of biometrics: anyone remember that Vietnamese shop (Bkav) who made a
big stir out of breaking Face ID a week after launch? Was that ever
independently verified, or has anyone else broken Face ID a year later?

I remember there being a lot of skepticism about their claim because they
didn’t go into that much technical detail, but rather seemed more interested
in winning press and fame (as well as being incredibly boastful about it).

Hopefully someone knows about the current state of Face ID security better
than I do, since I’ve been a little out of the loop.

~~~
BugsJustFindMe
Bkav seem to be a bunch of fear-peddling shysters. Their antivirus software is
notorious for false positives.

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vermaden
One more time to repeat and remember.

Fingerprint is at MOST 'username'. Never a 'password'.

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leeoniya
i wonder if you can just chop up 50 fingerprints an feed them to
[https://github.com/mxgmn/WaveFunctionCollapse](https://github.com/mxgmn/WaveFunctionCollapse)

~~~
extracoffeeplz
That's pretty amazing, though the fact that fingerprints are much less
symmetrical would be an issue for how it works, so my guess is no.

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westmeal
I always get a kick out of technical methods like this because all you would
really have to do is punch the owner in the face and use his or her
fingerprint to unlock the device. It's sort of like the 5 dollar crowbar from
xkcd.

~~~
gnicholas
True, although these methods can be used more clandestinely. If you punch
someone in the face and use their fingerprint, they know it.

If you compromise their accounts from the other side of the world by tricking
a fingerprint reader, they won’t know immediately. And you’ll have broken
fewer laws, and possibly be located in a country without extradition.

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mbrumlow
There actually is no proof that finger prints are unique. Last time I looked
into it. The same goes for DNA.

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electrograv
How could DNA be non-unique, except for identical twins or clones?

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tedunangst
There's a 1 in 2^46 chance that siblings born separately will have mostly
identical DNA, minus a few random mutations.

~~~
smolder
Even born separately from the same parents, or from different parents with the
same available genes to generate the same haploids?

~~~
tedunangst
Yeah, plus some infinitesimal chance your aunt marries your uncle and your
cousin comes out just like you, etc.

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justas
As a scientist I hate to find such mistakes in publications: "The test set is
used for scoring the candidate DeepMasterPrints during optimization. The
attack should be successful against these fingerprints as it is directly
optimized for them." Even if that's a typo..

Disclaimer. My team at Neurotechnology develops fingerprint recognition
algorithm VeriFinger which was used in this publication to look for
vulnerabilities of small area fingerprint sensors.

