Re: [NOISE] Cable-TV-Piracy-Punks

[mpd@netcom.com (Mike Duvos)]

A few more hopefully short comments...

perry@piermont.com ("Perry E. Metzger") writes:

 > 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."


inglem@adnetsol.com (Mike Ingle) writes:

 > The big latent assumption here being that you have only
 > one-way communication with the subscribers. DSS has a modem.
 > It could get a new key from a distribution center frequently
 > - i.e. every day. Then the pirates would somehow have to
 > update their keys daily, in real time. Once we have live
 > packet communication (cable modems or ISDN D-channel, for
 > example) the keys can be changed minute by minute, if
 > necessary.

Assuming Perry is right and a smart card could have its innards
transplanted into a hostile environment, the scheme you describe
would offer no real protection.  The compromised card would
simply do the communication with the Key Distribution Center and
give all the information to the pirates.  A low-bandwidth link,
such as a web page, would be more than sufficient to communicate
the required bits to everyone else on the planet.

The security of a smart card based system has to lie in the "data
cannot be recovered even by destructive reverse engineering"
aspect of it.  If this is not a given, then cards can be exactly
cloned, and one clone can tell others what they need to know to
prevent the duplication from becoming known to the other side of
any transaction.

--
     Mike Duvos         $    PGP 2.6 Public Key available     $
     mpd@netcom.com     $    via Finger.                      $