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Alan McKinnon writes: |
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|
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> On Thursday 17 December 2009 02:37:54 Robert Bridge wrote: |
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> > dd is pretty thorough... afterall, it writes to every single block on |
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> > the disk. |
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> |
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> And the resulting effect from doing that once is: |
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> |
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> Trivially easy to recover the data that was there just before you did |
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> the dd |
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> |
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> Why? Data on-disk is not a binary cell like ram. It is a magnetic |
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> pattern and the pattern from the previous write is still there IIF you |
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> know how to find it |
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|
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I disagree here. In theory it may be possible, but trivially? Seems no one |
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ever did it yet. |
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From <http://www.h-online.com/newsticker/news/item/Secure-deletion-a- |
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single-overwrite-will-do-it-739699.html> : |
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|
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They concluded that, after a single overwrite of the data on a drive, |
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whether it be an old 1-gigabyte disk or a current model (at the time |
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of the study), the likelihood of still being able to reconstruct |
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anything is practically zero. Well, OK, not quite: a single bit whose |
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precise location is known can in fact be correctly reconstructed with |
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56 per cent probability (in one of the quoted examples). To recover a |
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byte, however, correct head positioning would have to be precisely |
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repeated eight times, and the probability of that is only 0.97 per |
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cent. Recovering anything beyond a single byte is even less likely. |
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|
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Wonko |
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