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post #11 of 15
doing dd from one of the useful fake devices is a really awesome way to do it from just a simple linux boot disc smile.gif id use that just cause its creative than booting up a disc built for it... and it probably works better lol
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post #12 of 15
As others have said, what you want to do is open a ROOT terminal then:

Code:
dd if=/dev/zero of=/dev/sdx

where sdx is the hard drive you want to wipe.  It will be most likely sda.
One pass is all you need to make a modern hard drive's data unrecoverable. Ask any data recovery firm. Once data has been overwritten once it is *not* going to be recovered.
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post #13 of 15
Quote:
Originally Posted by thiussat View Post
As others have said, what you want to do is open a ROOT terminal then:

Code:
dd if=/dev/zero of=/dev/sdx

where sdx is the hard drive you want to wipe.  It will be most likely sda.
One pass is all you need to make a modern hard drive's data unrecoverable. Ask any data recovery firm. Once data has been overwritten once it is *not* going to be recovered.
one pass is suggested but ive heard even that is POSSIBLY recoverable... but not cheap and in no way or form possible for anyone without a clean room and lots of time...

7 passes is the NSA standard, every hard drive with classified data the military gets rid of has to be over written with 7 passes to be declassified so i always stick to 7 just because... or 35 if im in windows and using an awesome file shredder that supports gutmann

average person should be perfectly fine with one pass though
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post #14 of 15
Quote:
Originally Posted by EntTheGod View Post
one pass is suggested but ive heard even that is POSSIBLY recoverable... but not cheap and in no way or form possible for anyone without a clean room and lots of time...
Highly unlikely even with a clean room and MFM's.

Quote:
7 passes is the NSA standard, every hard drive with classified data the military gets rid of has to be over written with 7 passes to be declassified
1) It's a DoD standard (not NSA), and it says nothing about 7 passes. You can read the document for yourself: DoD 5220.22-M. Where 7 passes came from is a mystery.

2) The NIST has said that one pass is enough:

Quote:
According to the 2006 NIST Special Publication 800-88 (p. 7): "Studies have shown that most of today’s media can be effectively cleared by one overwrite" and "for ATA disk drives manufactured after 2001 (over 15 GB) the terms clearing and purging have converged."
Quote:
so i always stick to 7 just because... or 35 if im in windows and using an awesome file shredder that supports gutmann
Gutmann himself has never advocated 35 passes. He has made it clear that this is a misinterpretation of his paper. A quote from him:

Quote:
"In the time since this paper was published, some people have treated the 35-pass overwrite technique described in it more as a kind of voodoo incantation to banish evil spirits than the result of a technical analysis of drive encoding techniques. As a result, they advocate applying the voodoo to PRML and EPRML drives even though it will have no more effect than a simple scrubbing with random data. In fact performing the full 35-pass overwrite is pointless for any drive since it targets a blend of scenarios involving all types of (normally-used) encoding technology, which covers everything back to 30+-year-old MFM methods (if you don't understand that statement, re-read the paper). If you're using a drive which uses encoding technology X, you only need to perform the passes specific to X, and you never need to perform all 35 passes. For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do. As the paper says, "A good scrubbing with random data will do about as well as can be expected". This was true in 1996, and is still true now."

...In particular the drives in use at the time that this paper was originally written are long since extinct, so the methods that applied specifically to the older, lower-density technology don't apply any more. Conversely, with modern high-density drives, even if you've got 10KB of sensitive data on a drive and can't erase it with 100% certainty, the chances of an adversary being able to find the erased traces of that 10KB in 200GB of other erased traces are close to zero.
Quote:
average person should be perfectly fine with one pass though
Until someone can provide even one example of someone recovering meaningful data that has been overwritten, I will continue to do one pass.
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post #15 of 15
Quote:
Originally Posted by thiussat View Post
Until someone can provide even one example of someone recovering meaningful data that has been overwritten, I will continue to do one pass.
Maybe on one of those ancient Seagate drives from the 80's that are still kicking around. You definitely need the voodoo to erase those.

Otherwise, it's utterly pointless. Though as one of the very few anti-voodoo people on this forum, I'll warn you that most people around here LIKE their voodoo and won't easily give it up. I suspect this comes at least in part from their Windows upbringing, where it's frequently impossible to understand what's actually going on, and fixing problems often looks a lot like voodoo.

For modern drives (anything in the last 10 years or so) a single pass with zeros is sufficient to make the data unrecoverable without a scanning tunneling electron microscope. In a laboratory that's a seven-digit-plus and months-long undertaking, and isn't going to happen unless you've stolen a nuke or something and some government really REALLY wants to know where it is. If your threat model includes governments at this level, then you must consider physical destruction of the media.

One last note: After you think you've erased a drive, run a data recovery tool on it yourself and see what happens. You may be surprised.
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