Destroying a HDD

HDDErase or Active@killdisk one pass zero. If a disk has very sensitive data then it has to go a custom setting with killdisk using 7 pass - Bruce Schneier.

Does a good job - free for zero single pass.

Noticing the 'overkill' and 'paranoia' comments which is probably true at home, in a business and customer environment there are 'rules' that govern data including destruction which is one reason there are standards, for example it maybe a requirement with insurance that a certain destruction method is used.

 

Just drop the HDD in a river/ocean/sea. That way, they can't prove you destroyed the drive, which may raise some suspicions.

 

Interesting topic. I'm wondering if there is a truly definitive answer to this. I've tried researching this subject numerous times and for as many searches I've done there's as many different answers to the question. It would seem to me the best anyone can do is to make it totally impracticable of extraordinarily expensive for anyone to be able to recover data that's been overwritten. Techniques using magnetic detecting microscopes would leave me to believe that ANY data IS recoverable given enough time and money to do so. Too bad misinformation is a key weapon in keeping this subject controversial.

 

What exactly makes you believe this? Cause I am ready to bet that even with the most advanced "magnetic detecting microscope" it would be extremely hard (read it impossible) to retrieve data that has been overwritten.

 

Overwritten how many times is the question, I still place my bet on 7 wipe pass to be safe! That is if you really have something you want to hide

 

Well, of course this is only my opinion. I haven't seen any information or solid proof that data can't be recovered from the most sophisticated hardware/software available to government agencies or law enforcement. Computer forensics is growing in leaps and bounds and I personally do not believe that the authorities are ever going to give anyone the straight goods on what they can and can't do. I do agree however, that data overwriting can make it pretty much impractical or too costly to retrieve. If you wish to call that making it impossible then you're entitled to your opinion. I'm certainly not a physicist but from what I understand, magnetic signatures written to a disk remain on the disk until enough time has elapsed to degrade that magnetism to nothing. (I'm supposing on the order of thousands of years?). How deep can the most sophisticated piece of equipment read that signature? I really don't know. How shredded and fragmented does data have to be in order for it to be 100% impossible to recover? I don't know that either but given that us peons are never told the whole truth and given that authority governing bodies love to mix fact with disinformation leads me to believe on the side of caution. As fast as something new appears on computer technology it's almost obsolete in short order.
Call me paranoid if you want to but as I said, I have found nothing on the web to indicate to me that overwriting data will 100% positively keep a super machine from finding it if you got the time and money to do so.

 

Nitewolf,
my field is not in particular computer forensics, and I am not in any governmental agency, but if you read the famois Gutman's article about recovering overwritten data from magnetic support, you will notice that such recovery is possible because there is a "shadow" left when you overwrite data. I will try to explain myself better:

If on your hard drive you have a 1 (Positive) and you write a 0 (negative), the magnetization level will be higher than a 0 written on a 0. Such difference can be noticed only by very sofisticated equipment. And this is true with old technology hard disks. New and more dense hard disks are much harder to examine.

Please refer to Gutman's article and similar for precise explanation.

 

Thanks for the heads up and I will definitely have a look at that article. It could well be my paranoia is getting in the way of reason but with the way technology is gaining ground faster than a lot of people can grasp, maybe I'm suffering from an over abundant imagination . They can't see through your roof from space yet...... can they?

 

Maybe I'm missing something or Gutman wrote another article with new information but his conclusion is as follows on this page http://www.usenix.org/publications/library/proceedings/sec96/full_papers/gutmann/

To quote:
"Data overwritten once or twice may be recovered by subtracting what is expected to be read from a storage location from what is actually read. Data which is overwritten an arbitrarily large number of times can still be recovered provided that the new data isn't written to the same location as the original data (for magnetic media), or that the recovery attempt is carried out fairly soon after the new data was written (for RAM). For this reason it is effectively impossible to sanitise storage locations by simple overwriting them, no matter how many overwrite passes are made or what data patterns are written. However by using the relatively simple methods presented in this paper the task of an attacker can be made significantly more difficult, if not prohibitively expensive."
end quote.

As I read what he stated in the paper, if a PC's read/write head is slightly misaligned off track to the previous data, that data is still reasonably readable. To what standards are mass produced PC's made? Disk errors happen frequently. He also states that the length of time data is stored on the disk also has a bearing in whether or not the overwrite process would be successful.

 

Agree.

Yes. The story with salt water and hammer is overkill in most situations.

Make several encryptions and 5 up to 10 time 1 pass with different tools and/or random letters.

 

From Wikipedia:

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.

 

Who would pick you from the 6 billion people in the world and spend a fortune of recovering data from your drive?

 

I don't Know! But "They" are out there! You know those little round white
things they put in Asprin bottles?
They say they are to absorb moisture.
HA!!
Dang old Homing beacon! "They" can zip a AGM-114 Hellfire right into your
medicine cabinet,and say your dang old water heater exploded!

 

anyone who has tried to recover lost data on HDDs knows there is a simple equation that tells you what is recoverable and what isn't ............ Photos of the neighbours dog half out of shot = 100% recoverability; Really important data that you can't live without = 0 - ½% recoverability. If that ½% worries you then I'd give the HDD to a child under 5 years of age, preferably male, they are known to be able to destroy anything on the planet as the makers of Pelican cases are well aware going by their Lifetime guarantee

 

Why make several Encryptions? and 5 up to 10 time 1 pass with different tools and/or random letters? Really, you would be wasting hours of your time!

Just choose an Algorithm that fits your needs!

Wiping algorithms are kind of like Encryption, as in the majority of them generate random data!

Example

 

No just make your own algorithm and for free.

 

If it's really needed to go to the extreme, pour some sulfuric acid inside the case over the platter and not even the Hubble Telescope could ever put Humpty-Dumpty back together again.

 

I've always heard that it's not a matter of if but when a HD will go bad... so just keep using it, and soon nothing will be recoverable.

 

Lets see your very own algorithm? and the software you used that was free?

LOL not really, I guess if you ignore the fact the HD can be dismantled, and read!

I use backup drives, then I really don't have anything to worry about when It comes to loosing data on a drive that has been heavily used, I have already gone thru 3 drives, 1 was enough to get me to go and buy a couple backup drives for all of my important data.