Wiping Data and probability
Slartibartfast
Global Moderator-__-
I have a large amount of hard-drives i no longer use. I've been disposing of them. Having received a lot of used drives with data still on them in the past, I've been very careful to wipe my drives before i give or throw them away.
The way i do it, is by writing 0's over the drives 5 times (dcfldd if=/dev/zero of=/dev/sdX bs=4M)
I've always been told 5 times is good enough, knowing how hard-drives work i've always thought twice was more than enough.
In the face of wiping so much data, I've decided to do some research; turns out i'm right.
Here's a table:
remember 8-bits is one character. In court things must be proven "beyond reasonable doubt".
The paper in itself if pretty interesting: http://www.springerlink.com/content/408263ql11460147/fulltext.pdf
It goes on to specify old drives and new drives but the data is pretty much similar.
EDIT: The link seems to work in campus, must track the IP or something. Will upload it tomorrow.
The way i do it, is by writing 0's over the drives 5 times (dcfldd if=/dev/zero of=/dev/sdX bs=4M)
I've always been told 5 times is good enough, knowing how hard-drives work i've always thought twice was more than enough.
In the face of wiping so much data, I've decided to do some research; turns out i'm right.
Here's a table:
remember 8-bits is one character. In court things must be proven "beyond reasonable doubt".
The paper in itself if pretty interesting: http://www.springerlink.com/content/408263ql11460147/fulltext.pdf
It goes on to specify old drives and new drives but the data is pretty much similar.
EDIT: The link seems to work in campus, must track the IP or something. Will upload it tomorrow.
Comments
On a side note, most secure erase programs do at least 1 pass. The Flame Worm/Trojan/GOD randomly writes data and then delete it's file thereby removing any trace. Hopefully, I would write about it in detail when I wake up.
What you described is very similar to the shred utility, although i cant see how it can overwrite its own memory location without segfaulting before it completes.
I would then take a 5 pound sledge hammer with a chisel face on one side of the head and a short handle like this;
Zeroing out HDD's before getting rid of them, DBAN is a good tool to use.
Okay, so if I REALLY wanted to get rid of a hard drive (this is all true. We did this when my Nan wanted to get rid of her computer...)
I'd run a 35-pass gutmann on the sensitive files, then zero out the drive with DBAN. I'd then take the thing apart and remove the internal components making sure to run those ultra strong neodymium magnets across the platters a few times. Then I'd scrape the fuck out of the platters with the screwdriver I used to take the thing apart with initially (yes, I've actually done this before, I'll see if I can find the pictures) and frisbee it all out of the window, into the back yard. This is where I'd call up my friend so that we could sit in the garden and take shots at the platters with his high powered air-rifle, before throwing the lot into a metal shredder.
Might as well have fun when you're destroying data
If you want to delete something securely, don't use the recycle bin. I'm sure you understand how deleting a file conventionally doesn't actually delete the file, it just tells the HDD that the particular section of memory can be written to :thumbsup:
Stay safe!
If worst came to worst, I'd use the Thermite in my room to destroy my laptop HDD with a few hammer blows to the external Hard Drives and put them under the laptop so the thermite fucks them over, too. So what if it burns through the floor...
https://www.dropbox.com/s/7c34ezgjx8d5v8p/fulltext.pdf