Low-level Floppy Wipe

[Jubbens]

Since I'm not using a filesystem in a traditional sense, I need a way to wipe a floppy clean. It's not a format, because it doesn't write a format to the disk. It's more like writing 0's to every bit on the disk?

Is there and tool out there that can do this? Thanks.

[Candy]

Naturally unix has a tool that's 100% fit for the purpose.

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 dd if=/dev/zero of=/dev/fd0 

Get zeroes, write to disk.

For windows, you could try Winhex, it has a disk wiping utility, although I think they want you to pay. Of course you could try a free disk writer and feed it a 1474660 byte block of zeroes...

[Pype.Clicker]

Of course you could try a free disk writer and feed it a 1474660 byte block of zeroes...

Are you 100% confident in that number it seems not to be a multiple of 1024 (i expected the floppy to have an integer number of sectors and the same number of sectors on both side ...) 1474560 seems closer to a good value to me.

Which nicely means

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head -b 1440k /dev/zero >/dev/floppy

makes it too (still on unix systems ... and no, i quite don't like the dd things)

[Candy]

ok... my headache is worse than I thought! screwed up a numerical constant!

The 1474560 is better yes.

[smiddy]

Well, actually, if we're talking TPI, and REAL LOW LEVEL, then you would want to write zeros to every aspect of the disk, essentially unformating it. And if you're paranoid, then you'll want to ensure that you do it at least seven times with zeros and ones. Its too early in the morning to think of the actual numbers, but essentually you'd want to make one sector per track, then write all zeros, then all ones, seven times. Then reformat it back to whatever OS you're using. Oh, and don't forget the gaps, and interleaving depending on what you REALLY want to do.

[Candy]

If you want to erase it for security's sake, nothing beats a 1+ tesla magnet. Don't expect to use it afterward though... For normal erasure, you can probably use a fridge magnet

[smiddy]

Agreed!

[Solar]

If you want to erase it for security's sake, nothing beats a 1+ tesla magnet.

I can't judge the strength of 1 Tesla, but in what I've read on cryptography so far, repeatedly overwriting with random data is considered superior to using magnets.

[distantvoices]

@solar: I suppose thats the measure for: "sticking it to iron/steel and not being able to get it off afterwards." *rofl*

[Solar]

I did that with a 5,25" disk in the olden times, using a horseshoe magnet that fitted that description.

I was still able to hex-dump some of the contents using nothing but my C128, a 1571 floppy drive, and some hackish tools.

I don't trust magnets for reliably destroying data.

[smiddy]

For magnets to be effective, and why writing differing data to disk works better, you have to change the polarity of the field, hence the difference between a 0 and a 1. Most people only place a magnet on one way. Sure it destroys the field, but only in the one direction, once. You have to alter the field several times in order to be effective, hence writing ones, then writing zeros, opposite magnetic signatures due to the field differences. So when you plug a magnet into the socket and attach it to the floppy, turn it off and turn the floppy 90 degrees, do it all over again, at least seven times. ;D

[Jubbens]

The best solution for security purposes is a 9" butcher knife.

Since I'm deving under Windows 2000 pro, can you suggest one of those "free disk writers"? I googled it and got nothing.

I'd like to have the floppy wiping part of the same batch file that compiles it, so booting into Linux/BSD isn't an option.

[B.E]

Make a Image with all bytes being zero. Then use partdisk(or what ever you use to copy you files) to copy the hole Image to the floppy disk.

Realy to delete the data for good. I would leave it in a fire.

[Jubbens]

How would I make an image that's all 0's?

How big would it have to be? Isn't an unformatted disk about 2MB?

[AR]

A standard 2 sided floppy is 1440KB exactly.

As for how to generate an image, I would just write a simple C program but there should be a builtin way to do it.