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

interruptlabs.ca

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Re: I'm Building a Self-Destructing USB Drive Part 2

#51

Post by alister »

How about authenticating with an accelerometer rather than through skin conductivity? To unlock your USB device, or to avoid the self-destruct, you would wave it, tap it, spin it, or rotate it in a specific way before plugging it in.

Accelerometers are widely used by smartphones so I assume that the ICs are common and inexpensive (at least if bought in volume). A tiny battery would be needed as well.

Carrying the idea even further, maybe you could even do key entry this way. Imagine that the USB device stores encrypted data and you enter a short decryption key by tapping out a particular bit of music before plugging it in.

To get even fancier, maybe you can enter a hexadecimal key (0123456789ABCDEF) through various motions. For example, spinning the USB clockwise on your desk is a 0, flipping it from horizontal to vertical is a 1, waving it through a figure eight loop is an 8, rolling it along the long axis is a B, etc.

Re: I'm Building a Self-Destructing USB Drive Part 2

#52

Post by hakfoo »

_Adam wrote: post #34
mindslight wrote: post #16

First, a specification for Maximum Voltage does not imply that it is also a contract for the Minimum Voltage Required to Destroy Device. And even if it were, you're still missing a spec for the current/power required to destroy the device. I would guess that the maximum voltage spec is based on the forward/reverse voltages of the body diode (hence the alternative -0.6v rating that would actually be easier to hit with…

Exactly - and that maximum is the "minimum maximum" across all batches of the device. You might get a particularly resilient one that handles the 10V just fine. The encryption idea makes way more sense, and the means to short out the cap doesn't even require the device to be powered. The only implementation challenge is that now instead of combining a simple circuit with an off-the-shelf mass storage controller, you…

Back in ~2014, I had a newish 32Gb USB3 flash drive. At that time, premium mainboards had FireWire headers for front panel connectors, on board as well as USB2. Both are 2x5 headers and can easily be smashed on if the connector keying isn't really well done. The FireWire header can deliver 12v (apparently it can be "8-30v" but real PCs tended to deliver the voltage they had available). You can see where this went.

After being inserted in, the drive was dead on USB2. On USB3 it would work for a few minutes at a time. This became relevant when I discovered the drive still worked in that few-minutes-at-a-time fashion in 2021 and contained my old wallet with 30,000 Dogecoin on it.

Re: I'm Building a Self-Destructing USB Drive Part 2

#54

Post by microtherion »

russdill wrote: post #49
bArray wrote: post #40

Earlier quoted context omitted.

> Thus you're going to need a lot of energy to create the heat required to cook the silicon. Your chip may desolder itself from the board before it's been appreciably damaged. Yeah, this is a really weird and unreliable method for killing the flash. I would be more inclined to go the route of super high voltage. > Encrypt the bulk flash memory, store the key in supercap backed SRAM, and then zero out and short the RA…

Bonus points for a USB stick that with the correct knock algorithm (plug in 3 times, unplug for 10 seconds, plug in again) presents a secret partition, otherwise presents a dummy partition.

With an USB C stick, you could have a knock algorithm that involves plugging it in with a particular orientation pattern as well.

Re: I'm Building a Self-Destructing USB Drive Part 2

#55

Post by SexyCyborg »

jrootabega wrote: post #50
SpikeDad wrote: post #46

Earlier quoted context omitted.

I think it's more for Chinese communist police raiding her home. Since she runs mains voltage through the USB drive the thing would have to be plugged in.

wouldn't the act of destroying the drive be enough to convict anyway?

Yes, but they could not, for instance get data on or conversations I've had with other people and go after them. A firestop of sorts. It's far from a universal solution, just a very low tech, very theatrical option for very specific threat models

Re: I'm Building a Self-Destructing USB Drive Part 2

#56

Post by bArray »

microtherion wrote: post #54
russdill wrote: post #49

Earlier quoted context omitted.

Bonus points for a USB stick that with the correct knock algorithm (plug in 3 times, unplug for 10 seconds, plug in again) presents a secret partition, otherwise presents a dummy partition.

With an USB C stick, you could have a knock algorithm that involves plugging it in with a particular orientation pattern as well.

Technically speaking, you could probably also develop a USB-A that could do the same thing with a little mechanical and electric configuration.

Re: I'm Building a Self-Destructing USB Drive Part 2

#57

Post by mindslight »

russdill wrote: post #47
mindslight wrote: post #16

First, a specification for Maximum Voltage does not imply that it is also a contract for the Minimum Voltage Required to Destroy Device. And even if it were, you're still missing a spec for the current/power required to destroy the device. I would guess that the maximum voltage spec is based on the forward/reverse voltages of the body diode (hence the alternative -0.6v rating that would actually be easier to hit with…

eMMC already contains an area that can be used for this sort of thing: https://en.wikipedia.org/wiki/Replay_Protected_Memory_Block

By that Wikipedia description I don't really see how it could be used for such.
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