Good Thinking

Security keypad designed to thwart thieves – by being transparent

Security keypad designed to th...
Adhered over a door hinge, the input device (although not its screen) would be virtually invisible to thieves
Adhered over a door hinge, the input device (although not its screen) would be virtually invisible to thieves
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Adhered over a door hinge, the input device (although not its screen) would be virtually invisible to thieves
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Adhered over a door hinge, the input device (although not its screen) would be virtually invisible to thieves
Lead scientist Evgeniia Gilshtein works with a prototype
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Lead scientist Evgeniia Gilshtein works with a prototype

In order for a thief to bypass a security system's interface, they generally have to see that interface in the first place. That's why Swiss scientists have designed an access code keypad which is completely transparent.

Created via a collaboration between the Empa research institute, EPFL and the Paul Scherrer Institute, the prototype device consists of a thin clear polymer film substrate, onto which are inkjet-printed numerical buttons and circuits made of transparent ink. That ink contains indium tin oxide nanoparticles, and is electrically conductive.

The production process involves dying the film blue, once the ink has been applied. A high-energy light irradiation process is then used to sinter the buttons and circuits onto that film – this makes the ink considerably more conductive than would otherwise be the case. The blue coloration initially assists by helping the substrate to absorb the light, but that color ultimately disappears as part of the irradiation process, leaving the film transparent once again.

Lead scientist Evgeniia Gilshtein works with a prototype
Lead scientist Evgeniia Gilshtein works with a prototype

The finished product could be adhered to a surface anywhere near a door, safe, or other place with restricted access – as long as a power supply was available. As with traditional systems, punching in the correct code would cause the door, etc to unlock.

Only authorized personnel would know where the keypad was located, plus only they would know which buttons to press, in what order. Because the buttons themselves aren't visible, however, a nearby electronic display would help by showing users which numbers were being selected.

The lead scientist, Empa's Evgeniia Gilshtein, demonstrates the technology in the following video.

Source: Empa

Transparent security due to printed electronics

3 comments
3 comments
Oirinth
Security through obscurity ... never a good idea
Daishi
The tradeoff is apparent in the demo where there are just 4 keys making the pass key much simpler to guess as there are only 256 possibilities. Looking closely at it would tell you if some of the keys are not used at all or are used frequently lowering the search space even more. If the password was "1123" you could basically tell just by looking at it. This sounds useful in theory but in practice it would be less secure than the luggage from Space Balls. People needing to secure anything should probably start with NIST Special Publication 800-63B as a reference even though it doesn't translate exactly to this use-case.
Worzel
The surface reflection from either side of the hinge would be different, and easily detectable.
Alternatively, shining a pocket light onto the surfaces, would expose it.