From: tcmay@got.net (Timothy C. May)
Date: Mon, 1 Apr 1996 08:07:26 +0800
To: cypherpunks@toad.com
Subject: Re: [NOISE] Cable-TV-Piracy-Punks
Message-ID: <ad841310010210042650@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 4:34 PM 3/31/96, jim bell wrote:
>At 11:59 PM 3/30/96 -0800, Mike Duvos wrote:

>>Perhaps our resident VLSI and Alpha Particle expert, Timothy C.
>>May, could give us a guess as to whether Perry's "Nasty
>>Mechanism" is more or less likely than Maxwell's "Daemon."

I wrote a reply to this, about decoder cloning and fingerprinting, but my
Mac froze up for some reason...must be a message. Maybe I'll rewrite it...

Then I saw this comment, and my sense of irony was triggered:

>I don't know what Tim May will tell you, but over 10 years ago a technology
>was developed which is something like a scanning electron microscope,
>however with very low beam energies and is designed to be able to scan a
>chip and quantitatively measure the voltage at various/all points on the
>chip.  It can be thwarted by a thick coating on the chip, but most organic
>coatings can be removed with  a "plasma asher," a chamber designed to remove
>photoresist coatings on chips.

I wrote a paper on this, "Dynamic Fault Imaging," using voltage contrast
combined with image processing and chip data bases to locate the origins of
glitches and faults in microprocessors. However, voltage contrast is a lot
older than 10 years, and was in use in the early 70s--my group just
developed a kind of "time machine" for watching the propagation of
defective states inside complex logic devices.

Using such methods to look at the internal state of logic or memory devices
is incredibly difficult, though a sufficiently determined analyst might
discover some interesting things. (Check the archives for several articles
I've written on tamper-resistant and tamper-responding hardware.)

Hardware fingerprinting is an economic win over reverse-engineering
analysis to the extent that it costs a huge amount more to get a particular
key than the value of what's in the key.

--Tim May


Boycott "Big Brother Inside" software!
We got computers, we're tapping phone lines, we know that that ain't allowed.
---------:---------:---------:---------:---------:---------:---------:----
Timothy C. May              | Crypto Anarchy: encryption, digital money,
tcmay@got.net  408-728-0152 | anonymous networks, digital pseudonyms, zero
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