[109469] in Cypherpunks
Re: About Alpha radiation...
daemon@ATHENA.MIT.EDU (Lucky Green)
Thu Mar 25 06:09:16 1999
Date: Thu, 25 Mar 1999 11:44:47 +0100 (CET)
From: Lucky Green <shamrock@cypherpunks.to>
To: cypherpunks@algebra.com
In-Reply-To: <v03130303b31f8e2a92b7@[209.66.100.162]>
Reply-To: Lucky Green <shamrock@cypherpunks.to>
On Wed, 24 Mar 1999, Tim May wrote:
[quoting Jean-Francois Avon]
> >Back to silicon chips, unless I misunderstood my physics classes, Alphas
> >never
> >get there...
>
> Incorrect.
Given that Tim wrote the book on this particular topic, perhaps we can use
it as an example that much of what you learn as undergrad just isn't so. I
remember hearing the "alpha radiation is shielded by a sheet of paper" way
back in high school. The real story tends to be a lot more complex and
once you venture to the edges of the technology, the simple models often
have to be abandoned.
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.
Over the years, there have been a rather large number of posts by authors
that never ventured beyond the simple explanation of introductory texts.
Such texts are /not/ designed to give the full explanation. They just give
an explanation that tends to hold true in many, perhaps most, cases.
When it comes to security, you often don't worry about the 99.9% of
"normal" uses. You worry about the tiny fraction of non-standard uses. In
which case, the basic explanations frequently won't do.
Have fun,
-- Lucky Green <shamrock@cypherpunks.to> PGP v5 encrypted email preferred.
