[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 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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