Ciao,

Riguardo questo argomento, c'é un'articolo interessante su sans.org :
https://blogs.sans.org/computer-forensics/2009/01/15/overwriting-hard-drive-data/


Opinions on the required or desired number of passes to correctly
overwrite (wipe) a Hard Disk Drive are controversial, and have
remained so even with organizations such as NIST stating that only a
single drive wipe pass is needed to delete data such that it can not
be recovered (that is a wipe of the data).

The controversy has caused much misconception. This was the reason for
this project.

It is common to see people quoting that data can be recovered if it
has only been overwritten once, many times referencing that it
actually takes up to ten, and even as many as 35 (referred to as the
Gutmann scheme because of the 1996 Secure Deletion of Data from
Magnetic and Solid-State Memory published paper by Peter Gutmann,
[12]) passes to securely overwrite the previous data.

To answer this once and for all, a project was started in 2007 to
actually test whether or not data can be recovered from a wiped drive
if one uses an electron microscope.

[...]

The purpose of this paper was a categorical settlement to the
controversy surrounding the misconceptions involving the belief that
data can be recovered following a wipe procedure. This study has
demonstrated that correctly wiped data cannot reasonably be retrieved
even if it is of a small size or found only over small parts of the
hard drive. Not even with the use of a MFM or other known methods. The
belief that a tool can be developed to retrieve gigabytes or terabytes
of information from a wiped drive is in error.

Ary


2009/11/8 Paolo Cavarretta <[email protected]>:
> 2009/10/31 Luca Berra <[email protected]>:
>
>> se i dati erano sensibili e/o esiste la reale possibilita' di un serio
>> attacco mirato al recupero di porzioni anche minime di questi dati,
>> allora e' necessario stare attenti anche ai settori reallocati, perche'
>> questi
>> non vengono riscritti da un dd.
>
> ok, ho riletto e mi sa che stiamo dicendo la stessa cosa.
>
> ero stato tratto in inganno dal fatto che questa osservazione e' puramente
> accademica nel 99,99 per cento dei casi di analisi forense...
> dove non serve questo livello di analisi.
> nel restante 0,01 per cento puo' essere utile...ma sono casi
> dove le persone interessante non vengono a chiedere lumi
> su sikurezza.org :-)
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>
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