> I believe Dallas Semiconductor makes a micro with a self-destruct pin.
> Not sure how it works, maybe a high-current surge through certain parts
> of the die?  I wonder what would happen if you let a PIC output pin drive
> the primary of a step-up transformer whose secondary was connected to a
> well chosen pin on the chip?

I beleive it is SRAM based. It contains a cryptographic key for external
bus encryption (and maybe also some internal memory?). You connect a
battery to it. When an attacker removes the battery the secret info
fades away within seconds. When he triggers your self destruct mechanism,
the Dallas will activly erase the secrets.

Possible attacks are to a) cryptographically attack the external bus
encryption (as shown by Markus Kuhn with one of the DS5002) or
b) remove the battery off a frozen chip because SRAM cells retain their
memory for minutes/hours then, "open" the chip quickly and use chip
laboratory equipment to "read" the SRAM. c) find weaknesses in the
un-manipulated product to extract the secret during valid operation.

Or d) use the one very simple attack no-one has thought of before and
become famous :-)