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Comment by klodolph | Hacker News Reader

I was under the impression that a 3D print was overkill, that you could do this much more easily. Have the sensors gotten that much better?

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It's not only overkill, it probably doesn't work because the resolution is typically way to big.

http://qz.com/631697/a-regular-inkjet-printer-can-spoof-a-fi...

It should be noted that these are the same researchers in both articles. I would guess that the inkjet method didn't work otherwise they are just ripping off the police department?

It's overkill by a whole dimension; fingerprints are 2D.

No it's not overkill, and no, fingerprints are not 2D. The fingerprint scanners on iPhones (and I believe other phones as well) are capacitive, meaning they rely on the physical ridges in your fingerprint.

Fingerprints aren't 2D, but the sensor is. The sensor does not directly measure the height of the epidermal ridges. Rather, the varying thickness of the epidermic vary the dielectric between the conductive dermis and sensor. So you can replace the ridges with something completely 2 dimensional but with the same dialectic pattern. A normal home printer ought to be able to do that.

Ought to and can:

http://qz.com/631697/a-regular-inkjet-printer-can-spoof-a-fi...

From the link:

"The spoof worked on the Samsung and Huawei handsets, but not the Apple and Meizu ones"

indeed the iphone fingerprint does check if the objects are capacitive though, but that's a separate check. the "scan" is still just iirc. a infrared 2d cam

cough graphite powder cough

>fingerprints are 2D

>Fingerprints aren't 2D

I doubt very much that you could do it with a 3d print at all. Even direct casts from fingerprints have proved difficult to use to defeat the scanner. I don't think a 3d print would have the necessary resolution.

>I don't think a 3d print would have the necessary resolution.

I bought and run a Projet 3500(http://www.3dsystems.com/3d-printers/professional/projet-350...) at my day job. In the highest resolution mode, which is all we really use, it's 750x750x1600 DPI. You could definitely print an accurate finger with fingerprints on it.

You can almost 3d print at the atom level with the right kind of machinery...

Some FDM printers apparently have resolutions in the low 10s of microns.

This laboratory probably isn't using off-the-shelf consumer-grade 3d printer

One way I've seen it done is to create a PCB with heavy copper, and then use that to cast gelatin or some other skin analog.

http://torkjel.com/projects/attacking_fingerprint_sensors.pd...

Creating PCBs can be with very short turn around times or even in house.

I agree. Just mold and cast the finger.

A bigger question is, why do they need the fingerprint... The phone has a passcode too.

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