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Posted 22 September 2011 - 07:25 PM
Posted 22 September 2011 - 07:42 PM
Posted 22 September 2011 - 07:43 PM
Posted 22 September 2011 - 07:50 PM
Posted 22 September 2011 - 08:02 PM
Even if you write over a file with (unknowing) random bits, forensic analysis can still detect the original values of the bits in some cases.
The standard practice that I know of for permanently deleting a file is to write over it will all zeros, then write over it with all ones, then write over it a few times with random bits, and then to smash the hard-drive enclosure with a hammer and discard of it in protected land-fill.
As for truly random numbers -- electronic slot machine regulations in some jurisdictions actually require truly random numbers, not just pseudo-random numbers. These are generated from a real RNG device (which measures entropy from radiation, decay, thermal noise, etc), not a PRNG algorithm.
Posted 22 September 2011 - 08:08 PM
No. If I write '4' on a sheet of paper, then you erase it and write '7' in it's place, I can still see the imprint of the 4 on the paper.
you can just overwrite the data once with random values and result in almost absolutely irreversible deletion.
Posted 22 September 2011 - 09:26 PM
Posted 22 September 2011 - 09:29 PM
When I have to be certain something is erased and not recoverable... I use this tool:
Posted 22 September 2011 - 10:00 PM
Posted 22 September 2011 - 10:55 PM
Pretty simple system. If you have a blank HD and you write a file and want to remove that file write the XOR of it over the original data. It's even wear on the HD. Reading doesn't change the value for a magnetic drive so you've essentially just set all bits evenly.
Speaking of destroying HDs I put one on an industrial magnet before. Once you flick that switch anything on those platters are gone. (High frequency AC ftw?)
Posted 23 September 2011 - 12:07 AM
Posted 23 September 2011 - 01:27 AM
Posted 23 September 2011 - 02:03 AM
throw table_exception("(ノ ゜Д゜)ノ ︵ ┻━┻");
Posted 23 September 2011 - 03:20 AM
Posted 23 September 2011 - 04:47 AM
Posted 23 September 2011 - 07:41 AM
There's also the Gutmann Method, though I know little about it's necessity.
Electron microscopes don't really work that way. They need the sample to be treated and even then, it has never been published, not even for MFMs which were shown to be recoverable.
an electron microscope
Posted 23 September 2011 - 02:01 PM
Posted 23 September 2011 - 03:44 PM
It's simply an urban myth. It sounds romantic that there is some deus ex machina possibility, but it has never been done.
An electron microscope can't be used for that. You'd need a magnetic force microscope (ironically also called MFM), which is even more expensive.
an electron microscope