USB memory that self-destructs unless you lick your finger and insert it

Most people choose encryption when they want to keep the contents of their USB memory safe. As an idea that sets it apart from such ordinary methods, an engineer from Interrupt Labs, a Canadian company that handles custom-made embedded systems, challenged the design of `` a USB memory that must be touched with a wet finger ''.

I'm Building a Self-Destructing USB Drive - Interrupt Labs Blog

I'm Building a Self-Destructing USB Drive Part 2 - Interrupt Labs Blog

Interrupt Labs' Ryan Walker was inspired to create a quirky self-destructing USB stick by imagining becoming a journalist cutting into political corruption in a dangerous country. Since data encryption in such areas is never safe, Mr. Walker thought, 'I want to make a flash drive that requires a procedure that a decent person would never do.'

So what Mr. Walker came up with was the act of 'licking his fingers'. Specifically, it measures the resistance value of a finger when inserting an electrode into a USB drive, and if the finger is not wet, the data on the drive is blanked or the drive is destroyed. According to Mr. Walker, the resistance of a human finger is about 1.5 , but when the finger is wet, it drops to about 500 kΩ, so the point of Mr. Walker's idea is to use this resistance difference. is.

Flash drives are generally made up of a flash chip, outlined in red, which stores data, and a USB controller, outlined in blue, which is responsible for controlling data and connections. Walker planned to use this USB controller and a small microcontroller to read the electrodes and control the flash chip.

Mr. Walker, who immediately started looking for a USB controller, chose '

SM3257EN ' because it had a proper data sheet. I decided to use ' ATTINY24 ' for the microcontroller used to read the electrodes.

Below is a block diagram of the SM3257EN.

Mr. Walker next designed the outer parts of the USB memory while referring to the case of the flash drive sold without contents.

It will look like this.

Initially, Walker envisioned a flash drive in which the data would not be visible if the fingers were not wet, but after receiving feedback from blog readers that ``it cannot be said to be self-destruction,'' the data was cleared. It is now possible to switch between a mode that kills and a mode that physically self-destructs.

There are various methods of physical self-destruction, such as exploding or releasing a solvent or corrosive substance, but Walker chose a method that puts excessive voltage on the flash memory. It is said that 4.6V or more is required to disable the USB memory, and the circuit diagram is as follows.

And the circuit diagram of the device that detects whether the finger is wet looks like this.

Mr. Walker, who designed a self-destructing USB memory in this way, assembled a circuit with a

breadboard and tested it. First of all, if your fingers aren't wet, nothing happens.

However, when I licked my finger and touched it, the LED lit up to indicate that it worked. A GIF animation of the test can be seen from

this link .

Walker plans to fully document the self-destructing USB stick in an upcoming blog post and publish it as an open source project. He also said that he is planning a small crowdfunding to make the device.

GitHub - Machine-Hum/ovrdrive: The one and only, exploding USB drive

in Hardware, Posted by log1l_ks