[109486] in Cypherpunks
Re: CDR: Re: About Alpha radiation... (fwd)
daemon@ATHENA.MIT.EDU (Lucky Green)
Thu Mar 25 19:01:33 1999
Date: Fri, 26 Mar 1999 00:36:15 +0100 (CET)
From: Lucky Green <shamrock@cypherpunks.to>
To: cypherpunks@EINSTEIN.ssz.com
In-Reply-To: <199903251245.GAA12033@einstein.ssz.com>
Reply-To: Lucky Green <shamrock@cypherpunks.to>
On Thu, 25 Mar 1999, Jim Choate wrote:
[quoting Lucky]
> One of my favorite examples is DRAM. Yes, your DRAM may have a 60ns
> refresh cycle. Does this mean pulling the plug on your computer will
> permanently erase the key that was stored in the same DRAM segment for
> days? Not even close. Sure, the OS can't read out the key. But serious
> destructive analysis is able recover the key for weeks or months after you
> pushed that "emergency" button.
>
> ...
>
> ----- End of forwarded message from Lucky Green -----
>
> That's only partialy correct. The data could be recovered through long-term
> charge storage *provided* the memory isn't used after the power down. If
> it's powered back up and cycled even once then such data is destroyed
> permanently by being over-written with the new data.
I wasn't referring to long-term charge storage. Sigh. I guess my post did
not do much good, since the first reply to it totally ingored the main
thrust in it, namely that statements about phenomena not truly understood
by an author are often wrong and that textbook explanations are frequenly
simplified and thus may not suffice in analyzing non-standard scenarios.
One would have hoped the reader to pause for a moment before attacking
an example specifically chosen for its complexity and marked as such.
To assist in moving up from the high school/undergrad level understanding
of DRAM, I recommend reading
http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html
The paper does not tell the whole story either, but it certainly should
help the brash critic of my post to get a tad better up to speed.
-- Lucky Green <shamrock@cypherpunks.to> PGP v5 encrypted email preferred.
