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-   -   35 pass erase free disk space disk utility (http://www.mac-forums.com/forums/other-hardware-peripherals/148487-35-pass-erase-free-disk-space-disk-utility.html)

gravitate 04-11-2009 04:21 PM

35 pass erase free disk space disk utility
 
can the previous information EVER be recovered? Even with the highest technology ever invented?

chscag 04-11-2009 06:36 PM

It wouldn't surprise me if it could by the NSA or the CIA. The safest way to destroy the data on a hard drive is to physically destroy the hard drive and then melt what's left over. :)

Besides, a 35 pass erase on a modern hard drive could take days to complete.

Regards.

Santino 04-11-2009 08:14 PM

I recommend you swap or destroy the HD if you're that paranoid to be thinking on a 35 pass erase.

No offense, but as chscag said, deppending on the HD capacity it can go on for days until its done.

gravitate 04-11-2009 10:53 PM

actually guys its after a fresh re install. i am not bothered about time but just wondered if the info could ever be recovered with any technology. also what if the information that you want hidden was overwritten by the os. does this mean that it (or part of it) can be easily be obtained as its only been overwritten once by the os?
all answers are interesting as this subject is very interesting :)

Dysfunction 04-11-2009 11:27 PM

After about 7 passes the chances of it being recovered are rapidly diminished. At 35 it's going to be very difficult and someone would have to have very high end equipment and be determined to do so. That being said, DOD standard is to do the multi-pass erase then physically destroy the disk. There are shredders made specifically for the task ;)


BTW the multiple passes overwrite in 0 and 1 patterns, multiple different patterns each time.

Doug b 03-27-2010 06:24 AM

Microwave oven. Does the trick every time... :o O:)

doug

pigoo3 03-27-2010 11:34 AM

Quote:

Originally Posted by gravitate (Post 831572)
can the previous information EVER be recovered? Even with the highest technology ever invented?

According to this Apple document:

About Disk Utility's secure erase options

The DoD (Department of Defense)...actually only requires a 3-pass erase:

"The 7-Pass Erase option conforms to the DoD 5220.22-M specification. This specification calls for three passes, but Disk Utility performs seven."

So a 35 pass erase (in addition to taking an ungodly amount of time to perform)...would way way exceed what the DoD requires!

- Nick

the8thark 03-27-2010 12:27 PM

National Industrial Security Program - Wikipedia, the free encyclopedia
Quote:

As of the June 2007 edition of the DSS C&SM, overwriting is no longer acceptable for sanitization of magnetic media; only degaussing or physical destruction is acceptable.
So it means the standard now is trash the drive and melt the remains into a sticky blob. Or alternatively you sit it on a desk and place a heap of Neodymium magnets above it. And screw the data on the drive that way.

pigoo3 03-27-2010 03:28 PM

Quote:

Originally Posted by the8thark (Post 1024993)
National Industrial Security Program - Wikipedia, the free encyclopedia

So it means the standard now is trash the drive and melt the remains into a sticky blob. Or alternatively you sit it on a desk and place a heap of Neodymium magnets above it. And screw the data on the drive that way.

Thanks for the updated security procedure. I think that the Apple document I linked was of OS 10.4 "vintage"...so looks like things have changed.

It's certainly much more fun to come up with "physical" ways to make a hard drive unreadable...than simply running "Disk Utilities" over-write procedure 7 or 35 times!;)

- Nick

Jamie-Jamie 03-27-2010 03:35 PM

If you really, really don't want someone to find your old porn and 2008 tax return, take that disk and chop it in half with an axe.

the8thark 03-27-2010 03:47 PM

If your axe swing misses the round data holding circle disk part of the hard disk then they might be able to take the data holding circle disk part, hook it up to another working drive and extract the data that way.

But if you get axe happy and chop it into a million parts or use the magnets :).

But I like your way of thinking JJ. Woot! Let all your frustrations out with an axe.

Jamie-Jamie 03-27-2010 03:53 PM

Yes! A big magnet will work. If the rust particles on the platters are fully randomized, then I think recovery becomes impossible. But just to be safe, chop it up anyway.

Then burn it.

Slydude 03-27-2010 04:11 PM

Wonder if this thread is sufficient enough to convince my wife that I need a blowtorch. axes are definitely out of the question since we have already had one unfortunate incident involving myself, a large kitchen knife, and a knife sharpener.

harryb2448 03-27-2010 05:49 PM

To be doubly doubly sure toss the drive into a furnace. If it has sensitive information, cheaper to just replace.

Jamie-Jamie 03-27-2010 06:34 PM

Make it an atomic furnace just to be absolutely sure. That's also the green choice, since your hard disk becomes renewable energy! :D


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