SD card destruction

Projects General Guidance
1

Hi,

A recent posting has re-kindled my interest in old arduino project that I worked on several years ago but never quite perfected, maybe someone on this forum can help?

My question is, how can I automate the processes of physically destroying a SD card?

A few years ago I built a data-safe for SD cards, the idea was to build a tiny little arduino-controlled safe that would hold one or two micro SD cards. If the safe was tampered with (or even just moved) then the user would have 30 seconds to enter the correct code or the SD card(s) inside the safe would be destroyed.

The coding and electronics I managed without too many problems, making a suitable safe wasn't too hard either. The problem was how to destroy the SD card 100% reliably without any danger of damage/injury.

My first version used a tiny amount of home-made thermite. I wasn't too happy with this, the thermite was potentially very dangerous, hard to ignite automatically, and tended to destroy a lot more than just the SD card.

The 2nd version used an induction heater, this only worked with a mains electric supply, or a set of internal batteries which required constant charging. When playing with this version I discovered that some SD cards can take a surprising amount of heat before they stop working.

Neither method was ideal, is there a better way?

Here are some of the basic criteria I'm after...
I want to destroy a memory card - not burn down my house!
I don't want to hurt anyone who's near the safe when it burns the card (since it's most likely to be me!)
I don't want the safe to destroy itself, just the SD card.
Needs to be battery powered, not mains.
A micro SD card is tiny - so only a small volume needs to be destroyed.
I'd prefer a solution that doesn't involve dangerous chemicals (dunking in an acid bath for example)
No explosives! - I know they're fun, but I'm trying to be practical!

To forestall one of the obvious questions, my data isn't really that valuable - it just seemed like a fun project! (but you never know when MI6, the CIA or the WI might come after you.......)

I guess the best solution would be mechanical - something like an electric coffee bean grinder - if the safe is tampered with, the SD card get's dropped into a grinder and pulverised.

All suggestions gratefully received!

2

What about rigging up a miniature blow torch to melt it? Something like this....http://i596.photobucket.com/albums/tt49/bigbadbobby/e%20cig/DSC05892_zps5383d74f.jpg:original

3

As you appear to want to destroy only one SD card, why not have it in a carrier that has a high voltage battery switched to it to destroy it?

Weedpharma

4

rigging up a miniature blow torch to melt it?

That might work, would need to work out some way of pressing the button (servo?) and then checking it has actually lit (thermocouple?). Theoretically if someone knew the safe worked this way, then they could defeat it by blocking up any vents and starving it of oxygen.

high voltage battery switched to it to destroy it?

I had though of this, but wasn't sure a high voltage would be guaranteed to destroy all data - it might stop the memory from being read by normal means but maybe a professional could still extract some data? The advantage of completely melting the card means that you could be 100% sure the data is absolutely destroyed

5

Tape it to a small LiPo battery and short the battery. That will generate a lot of heat quickly, followed by a POP!

6

What about rigging up a miniature blow torch to melt it?

I love the creativity from engineers on this forum. Always very interesting to see what goes through their minds.

I recommend two safer, easier alternatives.

  • One, use a magnetic coil (place the sd card on the coil). If the arduino sends power through the coil it becomes magnetized, and it will wipe the sd card safely. it may even be reusable afterwards, but the data on the sd card will surely be corrupt and unreadable.
  • The second way is to buy a WTV020-SD-16P sound module you will need to hook up the circuit red wire to a relay, Part A (see attachment), and you will need to connect a PartB to 5 volts on the arduino. PartC will need to go to where the red wire leads in the schematic on the link I posted. PartE, hook to any pin you want, and PartD hook to ground. When PartE is energized, the relay is flipped, and the sd card gets 5.5volts, which overloads it within 30 seconds, and possibly the WTC020-SD-16P as well fries the sd card circuits from the inside out. No blow torch needed.

Relay.jpg

7

Silicium is extremely hard. A coffe been grinder should not be happy !

Think of the way some needle destroyers work : just a grinder wheel. What material ? To be tested : silicium carbide or diamond.

It will destroy the card, the chip, and produce a lot of heat.

8

use a magnetic coil

I believe this is a common fallacy, in reality a magnetic field will not damage an SD card - it's not a floppy disk!

9

I believe this is a common fallacy, in reality a magnetic field will not damage an SD card - it's not a floppy disk!

But holding a magnetic to a computer will wipe the memory and render the computer unusable correct? What is the difference? Does the sd memory work any different than the computers memory?

10

magnetic core memories are rarely used since... at least 50 years...

11

But holding a magnetic to a computer will wipe the memory and render the computer unusable correct?

A hard disk will be damaged by strong magnetic fields, SD cards use solid state memory which aren't effected. Google it, there's lots of threads on this subject.

12

Well scratch that idea, and forgive me for my failure.
How big is the safe? Why not put a cheap old school microwave in it(should be able to find one for $5 at a jockey lot) and use arduino to turn on the microwave?

Will a microwave mess up the sd card, or are sd cards immune to radiation too now?

13

Capacitor bomb. electromagnetic pulse.

localized, inside of the faraday cage that is the safe.

14

just a note, but everything you do on the net is recorded.
NSA monitors all activity, so any files you downloaded will be able to be received in the event your entire everything is wiped out.

yes, the gov't does have every single e-mail Hillary has ever sent, so, anyone who thinks they are gone, you would be mistaken. of course, the access to that archive is beyond top security.

15

Why not put a cheap old school microwave in it

I was hoping for a smaller solution - it also needs to be something battery powered, otherwise the potential data-thief could simply unplug the safe before breaking into it!

16

Any reason this wouldn't work then?

The second way is to buy a WTV020-SD-16P sound module you will need to hook up the circuit red wire to a relay, Part A (see attachment), and you will need to connect a PartB to 5 volts on the arduino. PartC will need to go to where the red wire leads in the schematic on the link I posted. PartE, hook to any pin you want, and PartD hook to ground. When PartE is energized, the relay is flipped, and the sd card gets 5.5volts, which overloads it within 30 seconds, and possibly the WTC020-SD-16P as well fries the sd card circuits from the inside out. No blow torch needed.

9 volt battery would be enough to do the job.

17

it took two days for the FBI to retrieve every text and every IM and every F.B. post from the Boston brothers. just in case you forgot about that. they interviewed every person they IM'd and then interviewed everyone those people IM'd.....

if your PC or Phone is connected to the NET, there is a copy of your data that is safely tucked away in the hands of the NSA, so you know it is safe from prying eyes.

if your project is to just prevent someone that you know from reading the data, a simple electric jolt will fry enough of the circuits to make it unusable.

if you are trying to rig a way to destroy data that the FBI and NSA might want, like files that Obama or Hillary, or any political figure from any political party or gov't or terrorist organization, or even any of the non-government crime organizations, then the chemicals might be more appropriate. don't forget to pre-destroy your card by removing the protective outer layers so that the innards can be accessed faster.

18

Yes, a little container of acid that's active against silicon (and the epoxy layers over the chip.) Then the 'destroy card if moved' function can be totally mechanical - the acid spills onto the card. It does make it difficult to move wen unlocked too.

19

Capacitor bomb. electromagnetic pulse.

localized, inside of the faraday cage that is the safe.

Hadn't thought of that one, but a quick google suggest that whilst an EMP will probablywipe solid state memory it's not guaranteed.

I've been doing some experiments since I posted my original thread, - wrap an SD card in a few centimeters of nichrome wire and pass about 10 amps for ten seconds through the wire and SD card starts to melt. That's similar to the induction heater I originally tried, but a lot simplier and should be within the power capabilities of a good battery.

But keep the ideas coming if there's a better one!

20

Yes, a little container of acid

I've heard they used to use something similar during WWI - sensitive documents (paper) would be stored in a filing cabinet with a glass container of acid at the top, if it was roughly handled, the glass would break, the acid would pour onto the documents and the secrets would be safe.