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