Wiping Out Data

[Tony Arnold]

Matthew Flaschen wrote:
> Felipe Figueiredo wrote:
>> On Tuesday 27 March 2007 07:10:35 Matthew Flaschen wrote:
>>
>>  
>>> That will rewrite the entire drive with gibberish 7 times (this can be
>>> adjusted).  That should mostly obliterate all data, then reformat the
>> Is it really different from 
>>
>> dd if=/dev/zero of=/dev/sdb
>>
>> ? I don't get it, why is it necessary to use random bits, instead of zeroing 
>> all bytes (including the FATs)?
> 
> Simply overwriting the data once does not mean it can't be recovered.
> The Department of Defense recommends overwriting 7 times with random
> data.  It is my understanding that shred can do this.  Someone said
> before that even:

This i true of magnetic media, because there is always residual
magnetism that can be read by sophisticated equipment. I'm not sure it's
true of USB and flash memory, but then I'm not sure how it works, so who
knows?

Regards,
Tony.
-- 
Tony Arnold, IT Security Coordinator, University of Manchester,
IT Services Division, Kilburn Building, Oxford Road, Manchester M13 9PL.
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