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New scientific data on wiping HDDS
There finally is some scientific evidence that one or a very low
number of overwrites is enough to wipe a drive in most situations. The paper "Overwriting Hard Drive Data: The Great Wiping Controversy" by Craig Wright, Dave Kleiman and Shyaam Sundhar R.S. looks at the issue using magnetic microscopy and both older PRML and newer ePRML HDDs. The full paper is available from Springer, but costs 25 USD. An extended abstract is he http://sansforensics.wordpress.com/2...rd-drive-data/ It suggests that one factor is how often a drive area has been written to previously. The authors give probabilities how likely successful recovery of overwtitten data is, depending on data lenght. |
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New scientific data on wiping HDDS
On Jan 17, 2:18*am, Arno Wagner wrote:
There finally is some scientific evidence that one or a very low number of overwrites is enough to wipe a drive in most situations. The paper "Overwriting Hard Drive Data: The Great Wiping Controversy" by Craig Wright, Dave Kleiman and Shyaam Sundhar R.S. looks at the issue using magnetic microscopy and both older PRML and newer ePRML HDDs. The full paper is available from Springer, but costs 25 USD. An extended abstract is he http://sansforensics.wordpress.com/2...ng-hard-drive-... It suggests that one factor is how often a drive area has been written to previously. The authors give probabilities how likely successful recovery of overwtitten data is, depending on data lenght. I'll stick to a single overwrite. Apart from anything else, to find critical data on a sector, you also have to decode the disk structure/ directory to know where the critical sector is. I could write next weeks lottery numbers on a used disk, then a do complete, single erase. To find the numbers, first you will have to work out from maybe 200,000 MFT entries, where the sector on my 500GB drive is. Then find and decode the sector. I think it will be quicker and cheaper to go an buy 14,000,000 lottery tickets. (This would also take care of the fact I might be lying about knowing next weeks numbers). Michael |
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New scientific data on wiping HDDS
Arno Wagner wrote:
It suggests that one factor is how often a drive area has been written to previously. The authors give probabilities how likely successful recovery of overwtitten data is, depending on data lenght. So is it suggesting that an area that has had a lot of writes to it is more likely to require more passes, or the opposite? Yousuf Khan |
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New scientific data on wiping HDDS
Previously Yousuf Khan wrote:
Arno Wagner wrote: It suggests that one factor is how often a drive area has been written to previously. The authors give probabilities how likely successful recovery of overwtitten data is, depending on data lenght. So is it suggesting that an area that has had a lot of writes to it is more likely to require more passes, or the opposite? It suggests that an area that was written to once and then overwritten once is easier to recover than an area that had data in it before the data to be recoverd (and one overwrite) were put there. This would mean that overwriting a disk several times with random data before using it makes it even harder to recover anything. If I understand the physics right, all data layer previous to the last one sort of blend together. However when you look at the numbers, even shorter data parts are very, very hard to recover. I would say that maybe it may be possible to prove a certain file was on a drive after one overwrite, but only if you know the file beforehand. And it will be expensive. But if this is a concern, best do several overwrites. Side note: Anoter conclusion would be that physical destruction done wrong is far less ecure than one overwrite. Arno |
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