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Software needed to completely erase a hard drive

The company I work for will be replacing it's desktop PC's in the summer. We would like to sell off the old PC's to staff or private individuals but are concerned that senstive data may still be accessible.

Can anyone recommend a program for completely erasing a hard drive so that nothing is retrievavble, even if somebody has advanced data recovery utilities.

Please only post with products you have first hand experience of.

Cheers

Andy
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metamatic
Asked:
metamatic
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2 Solutions
 
Lee W, MVPTechnology and Business Process AdvisorCommented:
NOTHING is going to make the drive unrecoverable - The US Government simply does NOT discard old hard drives that contain highly critical data.  That said, using software that will wipe things according to the US Department of Defense (USDoD) standard should get your data erased to the point that only the most dedicated theif will be able to recover it - and even then, they may have to wait years for appropriate technology to be developed.

I suggest you use Darik's Boot and Nuke - free and available here:
http://dban.sourceforge.net/

At the bottom of the page there's also links to similar products including commercial ones if you just don't want to trust free software.
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Pete LongConsultantCommented:
>>even if somebody has advanced data recovery utilities.

Unless you work for NATO  or the FBI any DOD standard Drive Wiper will do what you want ie the full version of @ctive Killdisk http://www.killdisk.com/
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Pete LongConsultantCommented:
lee beat me to it :)
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diasfCommented:
Hi metamatic,

You have a free way to do it... not the best or fasteste, I know, but works 100% sure!
- Delete all folders where you have sensible information.
- Pick any large file if may have, with no important information. A movie, maybe that's the best. Large, I mean, several 100's MB. Create copies of that file enough to fill up the full hard disk up to 100%.
- Erase them. Next, you can format the hard disk. If anyone can recover anything, they'll get several copies of the same movie!

As I told, this is not the fastest way. But for sure it works!

diasf
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Lee W, MVPTechnology and Business Process AdvisorCommented:
Actually, it doesn't.  Someone who wants the data can still access it.  You need MULTIPLE writes to get the disk into a state where the data is not practically recoverable.
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Zuhir ElgmatiCommented:
look ....if your data is very senstive there's 2 ways to protect your data ...the 1st way .... some companies destroy the HDD completely to make sure that no body can access to data , specially the HDD is very Low Price , comparison with importent data you want to protect.
2nd way use very high secure erasing softwares  like:  ( wipeinfo ) it's programe come with Norten System Works 2006

((  Back by popular demand, Norton WipeInfo allows users to permanently delete files or entire folders. WipeInfo wipes free and slack space and supports government specifications for secure deletion. WipeInfo is the only way to remove sensitive data from a computer. WipeInfo gives users that confidence that the sensitive data is really gone. WipeInfo integrates into Windows and is accessible from Microsoft Explorer menus. ))
the software is here:
http://www.symantec.com/home_homeoffice/products/system_performance/nsw2006/index.html
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garycaseCommented:
I've had some experience with very sophisticated equipment to recover erased magnetic media, and it's safe to say that if you use a program that erases the drives to DOD 5220.22-M compliance (the "gold standard" for a secure erasure) that you don't have to be worried about your data.

I wrote a fair amount of detail on this topic in my comments to an earlier question:
http://www.experts-exchange.com/Hardware/Q_21604886.html
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garycaseCommented:
... I didn't actually respond to your question, r.e. a specific program to use for this.  For ensuring that no data that's been erased is accessible, I like Hard Disk Scrub from  http://www.summitcn.com/download.html.   Darik's Boot 'n Nuke (dBan) -- as suggested above -- is also good, but has a different focus.

Hard Disk Scrub scrubs (to 5220.22-M compliance) all free areas of a disk.   So if you've erased something, emptied the recycle bin, and then do a Hard Disk Scrub it is GONE -- nobody's ever (realistically) going to recover it.

dBan is booted from a floppy & erases an entire disk (to 5220.22-M compliance).

So which one is better depends on your focus:  dban is easier to simply "kill" an entire disk;  Hard Disk Scrub is better if what you want to do is be sure files you've deleted are absolutely no longer accessible.
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CarlosMMartinsCommented:
What about the method of getting some powerful electro-magnets and swipe them across the disks?
I don't know how recoverable they would be afterwars (and it would depend on the magnet, the "swiping", etc)  - but it would be the fastest way. :)
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Lee W, MVPTechnology and Business Process AdvisorCommented:
You would need a STRONG, STRONG magnet.  Even then, I certainly wouldn't trust that to erase my drive.  Corrupt it, sure, but not erase it.
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diasfCommented:
leew,

You mean that after a complete rewrite to fill the HD to 100%, you can still recover what was there before the rewrite? How can that be possible if every byte in the HD has been rewritten? I'm not saying it's not possible. I just would like to know how is that possible.

diasf
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garycaseCommented:
... read the link I posted above ==> both leew and I posted a fairly extensive amount of detail on this topic in an earlier question (http://www.experts-exchange.com/Hardware/Q_21604886.html)
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Zuhir ElgmatiCommented:
what about  (some companies destroy the HDD completely to make sure that no body can access to data , specially the HDD is very Low Price)
do you agree Experts  garycase & leew
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Lee W, MVPTechnology and Business Process AdvisorCommented:
Read the FAQ on Darik's site:
http://dban.sourceforge.net/faq/index.html
Note and read the links to the papers by Peter Gutmann.

Excerpt from section 2 of "Secure Deletion of Data from Magnetic and Solid-State Memory" by Gutmann

In conventional terms, when a one is written to disk the media records a one, and when a zero is written the media records a zero. However the actual effect is closer to obtaining a 0.95 when a zero is overwritten with a one, and a 1.05 when a one is overwritten with a one. Normal disk circuitry is set up so that both these values are read as ones, but using specialised circuitry it is possible to work out what previous "layers" contained. The recovery of at least one or two layers of overwritten data isn't too hard to perform by reading the signal from the analog head electronics with a high-quality digital sampling oscilloscope, downloading the sampled waveform to a PC, and analysing it in software to recover the previously recorded signal. What the software does is generate an "ideal" read signal and subtract it from what was actually read, leaving as the difference the remnant of the previous signal. Since the analog circuitry in a commercial hard drive is nowhere near the quality of the circuitry in the oscilloscope used to sample the signal, the ability exists to recover a lot of extra information which isn't exploited by the hard drive electronics (although with newer channel coding techniques such as PRML (explained further on) which require extensive amounts of signal processing, the use of simple tools such as an oscilloscope to directly recover the data is no longer possible).
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garycaseCommented:
... lee is also correct that a STRONG magnet would be required to have any notable effect on a drive.   There ARE commercial degaussers specifically designed to do this, and some use sufficiently strong fields that they are approved by DOD and NATO for sanitizing classified data, but they are not inexpensive.   For example:  http://www.datadev.com/v90.html  ($13,995)
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CarlosMMartinsCommented:
Looking forward to reading Gary's Memoirs, when he find the time to write it! :)
Just don't let Hollywood turn it into a blockbuster... hehehe
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garycaseCommented:
" ... some companies destroy the HDD completely to make sure that no body can access to data ..." ==> that's certainly one method to ensure nobody can recover the data.   But it does require destruction of the platters (you can buy shredders designed to actually shred the media).   It's true, however, that at today's prices simply destroying the hard drive is a reasonable approach if you want to be absolutely certain that no new technology might make recovery possible.   Not, in my opinion, necessary to do this -- but it certainly works.

This is, however, largely an academic discussion.   Any drive erased to DoD 5220.22-M standards, particularly if it's ALSO run through a commercial hard drive degausser machine (see my last link) is certainly SAFE from any practical recovery of the data !!
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CarlosMMartinsCommented:
... or throw it inside a crate and stuck it in that wharehouse you can see in the end of "Raiders of the Lost Ark". :)
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metamaticAuthor Commented:
Many thanks for all the replies. I think either of the freeware products (DBAN or Hard Disk scrub) will be suitable. I'd rather not destroy the drives as it will considerably reduce the second hand value of the systems. (which is pretty small anyway!)
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garycaseCommented:
You're most welcome.   I'd agree that either product will work well -- assuming you want to leave the OS intact, I'd just (a) delete all of the data (w/Windows Explorer), and then (b) run Hard Disk Scrub in DOD compliant mode.
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