Re: [dm-crypt] Possibility for safe Luks partition delete functionality

[Arno Wagner <arno@wagner.name>]

On Thu, Dec 12, 2013 at 01:29:54 CET, Matthias Schniedermeyer wrote:
> On 12.12.2013 00:22, Sven Eschenberg wrote:
> > Well usually those SSDs don't use any ecryption key, as long as you don't
> > use a HDD password (supposedly). Of course they could possible create a
> > random key and then write 'zeros' during secure erase, which would
> > incidently result in random content.
> 
> As the Secure Erase on the SSD i tested only takes seconds, i would 
> assume they (optionaly) reset the key and mark all sectors for reuse in 
> the wear-leveling-table. And then erase the cells either in the 
> background or the next time they are used. IOW the data is not really 
> erase immediatly, only inaccessible by normal read commands.
> 
> > But judging from experience, it would be quite foolish to assume
> > manufactures do anything properly or the way you'd expect it ;-).
> 
> Excactly.
> There is no real way of verifying what actually happens and if it done 
> in a way that really is secure.
> 
> The "content"-key can be something like MD5(serial_no + generation_no). 
> Which looks random in each iteration, but would be easily cracked by the 
> manufacturer.

Indeed. Or the manufacturer has some kind of backdoor. That is why
I recommend several overwrites with zeros, followed by physical 
destruction for SSDs. Same, BTW, for "hybrid" drives.

Arno
-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
----
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