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I know about the USB devices that have a write protection switch that disables writing on the device side, are there devices that have a similar hardware switch that permanently erases the devices memory, or another method that can verifiably erase the data?

After watching this video I got the feeling that even snapping a micro SD card in half may not permanently erase the device, so I was looking for an alternative.

A switch or method to irreversibly destroy the memory could also partially answer this question but I worry that it would be harder to verify, since it is a trick you can only do once. Even devices that have a self destruct method of forgetting the devices encryption key require some trust from the user and the device to be plugged in at the time, the best answer would be a button that resets all the memory to 0.

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  • You could use thermite or acid to permanently delete the information.
    – anon
    May 29, 2017 at 13:25
  • @anon but you couldn't get on a plane with it then.
    – daniel
    May 29, 2017 at 13:26
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    this question sounds like a product feature overview - which makes it not a security question
    – schroeder ♦
    May 29, 2017 at 14:36
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    a raspberry pi with a ramdisk and usb host would allow destruction via removing power
    – dandavis
    May 30, 2017 at 18:58
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    Carrying a fully encrypted USB-Thumbdrive, assuming decent encryption, would be non distinguashable from a thumbdrive overwritten with random data (so it will be "erased" in advance).
    – Jonas Köritz
    May 31, 2017 at 6:56

2 Answers 2

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Tamper-resistant devices, like the PIN pads you see at cash registers, often store their keys in a CMOS chip that requires a battery to keep the storage refreshed. If the circuit detects tampering (someone removes a screw, or drills the PCB, or breaks a tripwire cutting into the epoxy, or trips whatever other sensors the manufacturer included), the battery power is cut and the memory is drained. The chips used for this are often in a BGA package, making it that much more difficult to access the interior pins. Adding a push-button kill switch into the tamper detection circuit would not be a problem, if one was needed.

The Mooltipass Mini offers securely encrypted password storage in a pocket-sized tamper resistant package. Three wrong guesses at the PIN and the master key is wiped. But it doesn't have a kill switch, and it acts as a keyboard, not a mass storage device.

I have never seen a tamper-resistant mass storage device of the kind you seek. That doesn't mean they don't exist; just that if they do, they have very poor marketing.

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  • This is useful, CMOS SRAM would take a little battery, it would forget what its holding quickly when disconnected (seconds or minutes at room temperature), and it looks like you can get 8 megabytes on a chip nowadays.
    – daniel
    Jun 7, 2017 at 20:04
  • @daniel, if you are interested in building your own solution, there are many extremely tiny Linux boards available now. Pick one, mount a MicroSD card, load up a mass storage USB emulator, and add an encrypting file system. Add a push button as a kill switch to wipe the on-board key, and you're set. (Designing and implementing tamper resistant packaging is left as an exercise to the reader.)
    – John Deters
    Jun 7, 2017 at 22:00
  • Deleting a key leaves me the problem of explaining a large encrypted file I cant open, or possibly having NOBUS open it later. so I'm looking for an instant or quick way of zeroing a large volume without damaging the memory.
    – daniel
    Jun 7, 2017 at 22:13
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There is no inexpensive commercially available device like this. The only devices that would provide unpowered data destruction would either be hazardous or of extremely low data density (128 bits).

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  • as dandavis said DRAM in a raspberry pi would lose its data quickly when power is removed. But that doesn't look like a commercial product anymore, its carrying around a mini computer in your pocket.
    – daniel
    May 31, 2017 at 6:41
  • There are lots of potential answers, but given the implied criteria of replacing a micro SD card, there are no solutions of appropriate size, capacity, and cost.
    – this.josh
    May 31, 2017 at 6:46
  • 128-bits is enough if the USB has hardware encryption and the key is placed in that 128-bit sector.
    – Lie Ryan
    Jun 5, 2017 at 3:11

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