Build in 2 flashdrives - don't lick your fingers, you see the regular drive with innocuous crap. Lick, and you see the real deal. Better, have a magnetic key or transponder that unlocks the real drive (and hides the innocuous one.) Doesn't draw the attention that a mysteriously not working drive does.
I'm Building a Self-Destructing USB Drive Part 2
41–50 of 57 posts
Re: I'm Building a Self-Destructing USB Drive Part 2
#42I don't like how it's engineered: the uC is completely overkill as the high voltage could be generated by a single transistor switcher that charges a capacitor, not unlike those "Joule thief" circuits used to light higher voltage leds with small batteries. The mosfet would then just switch that voltage, which could well be tens of volts or more. However, the working principle assumes the user's skin would be normally…
I don't like the initial assumptions: that a cop would never have wet fingers, or that you'd never miss the contacts or have partially dry fingers when plugging it in.
I would like to have seen something that triggers when the user says "by all means, have a look; I have nothing to hide".
Re: I'm Building a Self-Destructing USB Drive Part 2
#43Earlier quoted context omitted.
It would probably be better if the device self-destructed automatically if some kind of dead-man switch signal isn't given. Like having to press a button at least once a day or maintain reception at least once a day with an implant inside the owner's body; else it self-destructs. That way you aren't doing anything, it's their act of arresting you or sneezing your device that causes the destruction. If they want to ke…
Unless there is ample precedent or case law showing that this kind of rules-lawyering is acceptable, always assume judges would frown upon obvious attempts to subvert the intent of law by using the wording of the law. Unless of course you are a big company, in which case that seems to be the expectation. So the real advice here is just to be a very important person.
I mean, I would comply, the device just exists, is designed in a certain way, and wasn't designed by me.
If the law forcefully and physically separates the device from me, the device self-destructs of its own design. The law enforcers would be the ones at fault for destroying the evidence.
Re: I'm Building a Self-Destructing USB Drive Part 2
#44I have the flash drive pictured in the first image of Part 1, and I'd say it, almost self-destructs on its own purely from overheating. If you plug it in or read it, it gets hot, and if you write to it it gets rapidly hotter. I've never tried writing gigabytes, but some people online say it gets so hot the drive slows down and eventually starts throwing errors instead of writing data, until it gets a chance to cool down.
Re: I'm Building a Self-Destructing USB Drive Part 2
#45Why use a micro at all? You could have implemented the entire circuit with a couple extra discrete components to reduce complexity.
Re: I'm Building a Self-Destructing USB Drive Part 2
#46Earlier quoted context omitted.
I believe it's her "Emergency USB Drive Destroyer" https://www.youtube.com/watch?v=Gg0sdeAwN5A
Ah, yeah, I could see how that might help if it's robbers trying to get your bank pw/wallet key.
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.
Re: I'm Building a Self-Destructing USB Drive Part 2
#47First, 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:
Re: I'm Building a Self-Destructing USB Drive Part 2
#48First, 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…
I really like the idea of a failsafe, where if the device is locked in a cabinet for a month it becomes unusable.
Re: I'm Building a Self-Destructing USB Drive Part 2
#49First, 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…
> 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.
Re: I'm Building a Self-Destructing USB Drive Part 2
#50Earlier quoted context omitted.
Ah, yeah, I could see how that might help if it's robbers trying to get your bank pw/wallet key.
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?