USB Drive Keeps Your Secrets… As Long As Your Fingers Are Wet?

[Walker] has a incredibly fascinating new undertaking: a completely diverse get on a self-destructing USB generate. Alternatively of relying on encryption or other “visible” protection options, this device seems and performs like an completely normal USB drive. The only variance is this: if an unauthorized man or woman plugs it in, there’s no info. What separates approved access from unauthorized? Damp fingers.

It appears weird, but let us stroll by way of the wondering driving the principle. Initial, encryption is of class the technologically sound and right option to knowledge security. But in some environments, the mere existence of encryption engineering can be viewed as incriminating. In these environments, it is superior for the travel to show up fully normal.

The next aspect is the entry command the “wet fingers” element. [Walker] designs to have hidden electrodes surreptitiously evaluate the resistance of a user’s finger when it is becoming plugged in. He suggests a dry finger ought to be about 1.5 MΩ, but wet fingers are much more like 500 kΩ.

But why detect a damp finger as element of obtain handle? Nicely, what is a little something no normal particular person would do ideal ahead of plugging in a USB push? Lick their finger. And what’s a thing a microcontroller need to be equipped to detect very easily without the need of a ton of more components? A freshly-licked finger.

Of class, detecting soaked skin is only 50 % the equation. You still need to put into action a USB Mass Storage unit, and that’s the place matters get specifically interesting. Even if you aren’t into the covert factor of this gadget, the study [Walker] has accomplished into USB storage controllers and flash chips, blended with the KiCad footprints he’s already place with each other means this open resource task will be a good case in point for any individual looking to roll their personal USB flash drives.

Normal readers could remember that [Walker] was formerly doing work on a very extraordinary Linux “wall wart” intended for penetration testers, but the chip lack has place that ambitious project on hold for the time getting. As this establish seems to be to benefit from a lot less exotic factors, ideally it can prevent a comparable fate.