[dm-crypt] Does safe remove has a point on an encrypted drive?

Arno Wagner arno at wagner.name
Sat Sep 22 14:13:58 CEST 2012


On Sat, Sep 22, 2012 at 01:31:38AM +0200, Claudio Moretti wrote:
>  On Sat, Sep 22, 2012 at 12:29 AM, <antispam06 at sent.at> wrote:
> 
> >  That's about it. A safe remove command is needed? And if yes, does one
> > need something more complex than one pass?
> >
> >
> If your drive password is compromised, the filesystem is exposed, so in
> theory is possible to retrieve the content of the file, as if it was on a
> non encrypted disk.
> 
> So, in my opinion, yes, a safe remove command is necessary and with all the
> passes you may need (which depend on the confidentiality of the file).

It depends. For plain dm-crypt with a compromised passphrase,
do secure delete for a HDD. For LUKS with a compromised passphrase,
overwrite the header and key-slot area once for a HDD. For
LUKS with a compromised master key, same as for plain dm-crypt.

For SSD, do secure unit erase (ATA command), overwrite and
physical destruction.

Arno
-- 
Arno Wagner,    Dr. sc. techn., Dipl. Inform.,   Email: arno at wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
----
One of the painful things about our time is that those who feel certainty 
are stupid, and those with any imagination and understanding are filled 
with doubt and indecision. -- Bertrand Russell 


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