[svlug] 2 part Linux question

Sanatan Rai sanat at stanford.edu
Thu Jul 10 12:14:23 PDT 2003


: Marc Maxwell wrote:
: > I am curious about a couple of things. I want to wipe
: > data off of an IDE drive COMPLETELY, absolutely and
: > totally gone forever and NOT recoverable.


	I can hardly claim to be an expert on this, so please bear with
me.

	If you write random bits on the drive, then someone can get rid
of the noise easily by `averaging', and then use `standard' (?) data
forensic tools to recover the data.

	Similarly, writing the same character, 0 or # adds constant
noise, which is also easy to compensate for.

	Therefore, to really obscure data, write somehing definite, such
as the complete text of shakespeare. One way is to take various text
files containing all of Shakerspeare, the King James' version of the
Bible, and so on.  Cat the files in random order to produce big files.
Encrypt each, cat again to produce a huge 40GB file, and then write that
onto your drive.  In spite of the randomness, this is not random data.
It is very definite data, which no recovery tool can easily remove to
get earlier data, even if the exact sequence of operations is known.

--Sanatan

-- 
Sanatan Rai,                      | EMail: sanat at stanford.edu
Dept. of Management Sc. & Engg.   | Home: 143D Escondido Village,
Stanford University,              |       Stanford, Ca 94305.
Stanford, Ca 94305.               | 'phone: (650) 498 1655 (R)
                                  |         (650) 736 2109 (O)





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