So How Do You Make A Self-Destructing Flash Drive?

A self-destructing storage device that vaporizes its contents at the first sign of trouble would be an invaluable tool for many people, but good luck getting your hands on such a thing if you don’t work for a three-letter agency. Or at least, that’s what we would have said before [Walker] got on the case. He’s working on an open source self-destructing USB flash drive for journalists, security researchers, whistleblowers, or anyone else who really values their privacy.

When we previously covered this project in July, [Walker] had only planned to make the flash drive hide its contents unless you knew to wet your fingers before plugging it in. We admit it sounds a little weird, but as far as clandestine methods of activating something goes, it’s pretty clever. But based on the feedback he received, he decided to go all-in and make the USB drive literally trash itself should it be accessed by somebody who doesn’t know the secret.

An elegant weapon for a more civilized age.

But how exactly do you pull that off? Sure we’d love to see a small thermite charge or vial of acid packed in there, but obviously that’s not very practical. It needs to be safe to carry around, and just as importantly, unlikely to get you into even more trouble with whoever is searching through your belongings. To that end, [Walker] thinks he’s come up with an elegant solution.

The datasheet for his flash memory chip says the maximum voltage it can handle before releasing the Magic Smoke is a meager 4.6 V. So he figures running a voltage doubler on the nominal 5 V coming from a USB port should disable the chip nicely with a minimum of external drama. Will it be enough to prevent the data from being recovered forensically? We don’t know, but we’re eager to find out.

In the write-up, [Walker] takes readers through the circuit designs he’s come up so far, and shows off the source code that will run on the ATtiny25 to determine when it’s time to toast the flash. He says by the next post he should have the entire flash drive built and documented, so stay tuned.

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

[Walker] has a very interesting new project: a completely different take on a self-destructing USB drive. Instead of relying on encryption or other “visible” security features, this device looks and works like an utterly normal USB drive. The only difference is this: if an unauthorized person plugs it in, there’s no data. What separates authorized access from unauthorized? Wet fingers.

It sounds weird, but let’s walk through the thinking behind the concept. First, encryption is of course the technologically sound and correct solution to data security. But in some environments, the mere presence of encryption technology can be considered incriminating. In such environments, it is better for the drive to appear completely normal.

Toggling the chip enable (CE) pin will hide the drive’s contents.

The second part is the access control; the “wet fingers” part. [Walker] plans to have hidden electrodes surreptitiously measure the resistance of a user’s finger when it’s being plugged in. He says a dry finger should be around 1.5 MΩ, but wet fingers are more like 500 kΩ.

But why detect a wet finger as part of access control? Well, what’s something no normal person would do right before plugging in a USB drive? Lick their finger. And what’s something a microcontroller should be able to detect easily without a lot of extra parts? A freshly-licked finger.

Of course, detecting wet skin is only half the equation. You still need to implement a USB Mass Storage device, and that’s where things get particularly interesting. Even if you aren’t into the covert aspect of this device, the research [Walker] has done into USB storage controllers and flash chips, combined with the KiCad footprints he’s already put together means this open source project will be a great example for anyone looking to roll their own USB flash drives.

Regular readers may recall that [Walker] was previously working on a very impressive Linux “wall wart” intended for penetration testers, but the chip shortage has put that ambitious project on hold for the time being. As this build looks to utilize less exotic components, hopefully it can avoid a similar fate.

A Very Buttoned Up Raspberry Pi Media Server

Projects that turn the Raspberry Pi into a low-cost Network Attached Storage (NAS) solution are very common; all you need is the right software, the Pi itself, and some USB storage devices. But unless you particularly like the “Medusa” look, with loose cables running all over the place, you’ll probably want to put the hardware into a suitable enclosure. Unfortunately, that’s where the somewhat unusual layout of the Pi can make things tricky.

Which is why [AraymBox] came up with this unique “capsule” enclosure for the Raspberry Pi and two USB-attached hard drives. Every effort has been made to keep the outside of this design as clean and streamlined as possible. The asymmetrical loops of wires that we so often see on other projects are gone, with everything been brought inside thanks to some clever wiring. This enclosure looks like a professional product, and if you’re willing to put in the effort, you can have one to call your own.

The good news is that the 3D printed enclosure only has four parts, albeit rather large ones, and none of which require support material. So it should be an easy print even on a relatively low-end machine. Of course, you’re not going to get that futuristic metallic look without a little work. You’ll need to do a considerable amount of sanding, filling, and paint work to get that kind of a surface finish. Then again, that rough “just printed” look has a certain cyberpunk appeal to it as well.

But the printed enclosure is only half the battle. Inside, [AraymBox] has soldered the USB to SATA adapter cables directly to the Raspberry Pi to keep things tight and compact. A micro USB breakout board was then used to add a power connector on the back of the device where the Ethernet and USB ports are, solving the issue of having one lonely USB cable coming out of the side of the case.

In the past we’ve seen other attempts to create a 3D printable enclosure for Pi servers, with varying levels of success. While some would argue that the better solution is to just throw the Pi and the drives in a large enough enclosure that it doesn’t matter what the wiring looks like, we appreciate the effort that some hackers are willing to put in to make something custom.

Dead HDD Smartphone Stand Still Holds Secret Data

We’ve actually got a few dead hard drives collecting dust so when we hear about a project that finds a use for one we perk up a bit. But we were somewhat disappointed when we discovered this was a smartphone stand, pen holder, and LED lamp in one. We just don’t have a use for this kind of triple-tasker. But wait… the dead drive has a secret. It still serves as data storage, if you know how to enabling the drive within.

As you can seen, [Samimiy] removed all the guts of the HDD, repurposing the platters and mounting brackets as the phone holder, and mounting plate for a couple handfuls of LEDs. The lamp portion can be adjusted thanks to the articulated based from a small desk lamp he had in his parts bin. The device receives power from the USB connector you can see in the upper right. That’s where the first part of the secret comes in. This isn’t just supplying power, it provides a USB connection to the thumb drive hidden inside the HDD case. But just connecting it to your computer won’t mount it. [Samimy] took the light sensor from an automatic nightlight and set it up below the pen holder. If you shine a flashlight down the hole in that piece of wood it will routed power to the secret USB drive causing it to enumerate on your system. Pretty clever! Take a look at his build video after the break.

We wonder if there’s a way to incorporate this light-based lock system into that mouse-mounted thumb drive.

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