Re: Re: [PAPER] Juggling with packets: floating data storage

[Michael Sierchio <kudzu () tenebras com>]

Jason wrote:
> May I draw your attention to an old Gutmann paper that is still very 
> much worth the read.
>
> http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html
>
> There is another paper that is also worth the read but sadly I've lost 
> the last reference to it I had.
>
> Deletion of data in RAM and even replacing it does not ensure that the 
> old data is not recoverable.

Even the overwriting scheme proposed is not workable in practice,
at least not for hard drives or compact flash media -- both of
which silently remap sectors when "difficulties" are discovered,
such that it is impossible to write to them again because they
are invisible to the OS -- but they're visible to direct forensic
examination.

Only a CPA-IND encryption scheme in which keys are managed
separately from the filesystem, and where a key-per-file
scheme is in force, and where directories are similarly
encrypted is there any degree of provable secure deletion.


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