From: jim bell <jimbell@pacifier.com>
Date: Mon, 1 Apr 1996 03:31:28 +0800
To: cypherpunks@toad.com
Subject: Re: [NOISE] Cable-TV-Piracy-Punks
Message-ID: <m0u3Q6D-0008xCC@pacifier.com>
MIME-Version: 1.0
Content-Type: text/plain


At 11:59 PM 3/30/96 -0800, Mike Duvos wrote:
>A few more hopefully short comments...

> > Why not? If the card knows its own key, then someone else
> > can probably get the key out by some nasty mechanism.
>
>There is no physical difference between cards.  The key
>information is stored in EEPROM, and the links which permit the
>EEPROM to be written are burned after programming is complete.
>The EEPROM data is then only accessible to intimately associated
>circuitry in its vicinity.
>
>Presumedly the state of the EEPROM cannot be deduced by any
>external examination of the card, and any attempt to
>incrementally abrade the card down to the relevent circuit
>elements should completely obliterate the minute charge
>differences which represent the data.
>
>At least, that's the theory.  The Europeans trust this technology
>well enough to let it represent real money, so presumedly they do
>not consider hacking a possibility.
>
>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 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.

Jim Bell
jimbell@pacifier.com