A.P. Lawrence

clearing memory

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From - Mon Jan  3 06:37:06 2000
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Subject: Re: Memory purge References: <84oi1c$65j$1@nnrp02.primenet.com> <8c107sgn55mfv8e2et8lg0flpj1btrkllv@4ax.com>
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In article <8c107sgn55mfv8e2et8lg0flpj1btrkllv@4ax.com>,
Jeff Liebermann  <jeffl@comix.santa-cruz.ca.us> wrote:
>Dynamic RAM does not permanently store bits.  Turn off the power, and all
>the stored bits are cleared.

DRAM can maintain its contents for seconds, even minutes, after
losing power.  If absolute certainty is required, removing the power
isn't good enough.

>However, since you insist on economy, I suggest you simply run:
>    sync; sync; sync
>    /usr/bin/yes "Garbage and more garbage" > /dev/kmem
>which is guaranteed to overscribble all of memory.

Including the kernel and the "yes" executable and its shared
libraries which are all resident in memory.  You'd have no guarantee
that all of memory was wiped before the wiping program itself was
wiped.

I see no way that this can be accomplished under something like OSR5.
I think you'd need a dedicated program you could boot from a floppy
to do the job.  Or swap the RAM modules before handing the machine
over to the insecure party.
-- 
John W. Temples, III

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