Little knowledge, just an idea, need a learning starting point

[dumbnoobidiot]

I know very little about computers. I know enough that I was able to put together my own desktop, and I have a pretty good grasp of programming (I've played around with Unity here and there), but beyond that, I don't even know what I don't know. And I got this idea that, at the very least, I think would be cool. (A matter of opinion, of course.)

The idea goes like this: You have a battery powered device attached to a usb flash drive. While the device is off, you can use the flash drive normally. However, with the flip of a switch, the device turns on and erases everything on the flash drive.

I do believe I could cobble something together... eventually? But there would be a lot of grasping in the dark before I had something that wasn't completely embarrassing to look at.

So, my question is this: What do I need to learn so that I can make this as small and simple as possible?

[topguy]

Will the flash drive be in use when you turn the switch on ? or can you guarantee that will not happen ? Will the flashdrive be selfpowered ?

You will have to make sure that you dont have two compunters accessing the flashdisk at the same time so you would have to learn to electricly isolate the usb data-lines. So your task is more electronics than computers IMO.

[W. H. Heydt]

Do you care whether you *erase* the contents of the USB stick, or will *destroying* the USB stick meet the goal?

[thagrol]

Consider this approach.

Instead of using an off the shelf USB flash drive use a large SD card and a Pi zero.

1. Install raspbian lite on the SD card and do the usual first boot stuff.
2. Create a big file somewhere on the SD card. As big as you want your virtual USB stick to appear to be on the host.
3. Set up the zero as a USB mass storage gadget using the file created above as its backing store.
4. Have a script running on the zero to wait for a button press then do this:
   1. Kill/rmmod the g_mass_storage module. That stops access from the USB host. We don't care whether the host has unwritten data in its write cache as we're going to erase the backing store anyway.
   2. Run a secure erase on the backing store. This will take a while and may need the storage to be mounted locally first.
   3. Optionally, repartition and reformat the backing store ready for the next use.

The above is just the essense of what you're trying to do. There are a whole host of other issues you'd need to deal with to make it robust and fully secure many of which would also apply if using a Pi as a middle man between the USB host and the USB flash drive.

[mwrich4]

Truly erasing flash take TIME.

If this is a panic mode ability, I suppose it's technically viable with another small autonomous processor. But it's a LOT of design work as stated above.

Otherwise, most of us just insert and delete in a system.

[Botspot]

You have a battery powered device attached to a usb flash drive. While the device is off, you can use the flash drive normally. However, with the flip of a switch, the device turns on and erases everything on the flash drive.

Question: Does this "battery powered device" NEED to be attached to the usb flash drive AT ALL TIMES? If so it needs to be very small.

Sounds like you want a device that will erase everything on the usb device. How about a standalone device? Plug in any usb storage device, push the button, and >BOOM<, contents erased.

Diagram:

usb_eraser.png (24.07 KiB) Viewed 108 times