Hey Sup Forums why do i have to write random numbers all over my harddrive multiple times to wipe all the data? Why isnt writing a 1 in every "memoryslot" enough to make everything non restorable?
Hey Sup Forums why do i have to write random numbers all over my harddrive multiple times to wipe all the data...
Oliver Roberts
Hunter Bell
Id really like to know why i have to let my laptop clear itself for over 90 hours and why even that might not be enough
Mason Williams
Zachary Roberts
cat /dev/one > /dev/sda
Michael Long
i read the whole article and my question remains. maybe its there and im just too stupid to understand it tho.
and this is just random letters to me. it seems to have something to do with linux and overwriting i guess but i dont understand the statement
Jordan Wilson
Because you have to garble the data that sits there to make the old data as unreadable as possible. When you delete a file, the data doesn't actually leave the hard drive. It just sits there until it's overwritten. A lot of people just do degaussing, but that doesn't always work. The best way to clear data is just to overwrite it with random 1s and 0s, through 7 passes. This is a standard that the Department of Defense uses on all of their drives with sensitive data once it's no longer needed.
Nolan Jackson
Aside from completely destroying the drive if it no longer functions correctly, mainly because it is still entirely possible to get data off of it.
Tyler Cox
yes i know that. i just didnt understand why overwriting it once isnt enough? but i guess if i change the magnetic state from 1 to 0 it might end up as something like 0.0001 and then someone would be able to interpret it as a 1 before the overwrite happened. i didnt think analog enough when i asked my question
Easton Wright
Because the way the disk wiping software works. You will never be able to fully wipe a drive in one pass. Hard drives are simply too big for that, and if they are FILLED with data, then you seriously need to make at least 7 passes. It'll never happen, at least for now.
Now, I don't have any experience recovering data from drives that have been passed through at least once, but I do have experience in wiping disks. The only way to completely "wipe" a HDD is to physically destroy the platters. Degaussing and wiping disks has never been completely foolproof.
Bentley Nguyen
People in this thread are dummies, OP. On a HDD, each bit is made up of many many atoms. Every last one doesn't get its magnetization changed when you change the bit, and those left over ones can reveal what was there before.
Charles Lopez
yea i figured, thank you
Sebastian Phillips
>dd if=/dev/zero of=/dev/sda
I'd like to see some proof that after this operation any data is recoverable. Even if the old state of a few bits could be read it wont be enough to reconstruct the file system or any files on it.
There are some tinfoil theories but nothing else. If you ask a data recovery company to recover a dd zeroed disk they'll tell you that it is not possible.
David Morris
Not everyone is using Linux though m8.
William Moore
it might have been possible to recover something 20 years ago (1996), impossible with today's ultra-high density drives.
Colton Ward
t. NSA agent
Robert Gonzalez
Learn to ATA secure erase.
With decent disks you can get a completely secure wipe in under 5 minutes.
Lincoln Walker
It is basically writing the whole disk with zero bits once. Equivalent to what OP asked and the standard for wiping a disk.
Some people in this thread are claiming that multiple passes or random data is required but I've seen no evidence that it is required.
Aaron Bennett
you might as well just smash your drive right away instead of waiting for it to be wrecked by 35 overwrites.
t. NASA astronaut
Ayden Ortiz
I don't think you do if it's an SSD.
as for a magnetic drive, picture (depending on how old you are) recording over a cassette tape and hearing the original faintly in the background.
I don't really know what I'm talking about but I imagine it's something like that
Charles Peterson
i've certainly used cassettes in my youth but i never encountered this phenomenom. but ur probably right!
u have a point there. i scheduled 35 overwrites and its currently at the 6th. will my harddrive really suffer that much from it? maybe i should cancel after the seventh wipe.
Xavier Miller
seven should be more than enough.
Christopher Kelly
Residual magnetism. The bits on harddrive aren't truly digital: there's merely a threshold on the charge each bit has: if the charge is above the threshold, it's a 1, if it's below, it's a 0. Zeroing the HDD doesn't actually ensure that there is no charge, it just means that there's no charge over the threshold. Zeroing it twice leaves less charge than zeroing it once. Therefore, if you have sensitive enough instruments, it's at least theoretically possible to figure out whether a particular bit was 1 or 0 before it was zeroed. Whether it's actually possible to do this on a multi-terabyte HDD with modern instruments(and do it in a practical manner, no less) is something you'd have to ask from an intelligence organization like NSA, but the theoretical basis for doing it does exist.
Nolan Butler
>Whether it's actually possible to do this on a multi-terabyte HDD with modern instruments(and do it in a practical manner, no less) is something you'd have to ask from an intelligence organization like NSA, but the theoretical basis for doing it does exist.
Not very worried about this. I'd expect NSA and similar organisations to focus on hacking rather than hoping they land a single zeroed drive with no encryption.
I haven't seen commercial companies offering data recovery from a single zeroed drive so to me it seems that it is super hard to impossibe..
Elijah Allen
This is how file deletion works (more or less)
youtube.com
And that is why you should write random bits to your drive
See more here
wiki.archlinux.org
wiki.archlinux.org
James Butler
you don't have to write random bits to wipe the data. a single pass of 0x1 or 0x0 is enough on modern HDD. the myth of needing to write multiple times comes from ancient disks that didn't use the magnetic surface efficiently enough, so there could be left over information
damaged sectors can still retain data, but the ATA secure erase command will wipe those too.
writing random data is useful if you're going to be encrypting the drive, because it makes it harder to determine information about the data you are now storing encrypted on the device. /dev/urandom is suitable for this
Asher Anderson
There's also the fact that the DoD still requires a certain number of passes (regardless of whether it's actually necessary), and if the military does it, then it's "good enough" for everyone else.
Kind of like NIST. There are technically no regulations that state cryptographic applications and/or companies/industries are required to use AES for the encryption algorithm, but because that standard is what NIST recommends for government usage, it becomes the "defacto" standard for private industry which trickles down to us consumers.