[53060] in Cypherpunks
Re: [NOISE] Cable-TV-Piracy-Punks
daemon@ATHENA.MIT.EDU (jim bell)
Sun Mar 31 12:02:20 1996
Date: Sun, 31 Mar 1996 08:34:21 -0800
To: mpd@netcom.com (Mike Duvos), cypherpunks@toad.com
From: jim bell <jimbell@pacifier.com>
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
