Nice ideas, but...

> Or if you have need of a secure chip, pot the chip and run a 
> thin thin wire
> through the potting, tie the wire to a input and output, and 
> check if the
> wire is there.. If its not, the potting was removed and erase 
> the code..

But you'd need power to do the erasing. You'd need to include a battery
in the potting. An attacker might cool the thing down below the
battery's working point and then remove the potting, and lateron
reisntall the wire.

> Also you can destroy the bond wires for RB7 and RB6, I've 
> seen that was done
> somewhere by someone, perhaps on the list archives..

If you can destroy them someone else can reinstall them. After all
factories do that all the time.

Nothing wrong with extra security measures, but don't let them give you
a false sense of absolute (or even 'high') security.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
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docent Hogeschool van Utrecht: www.voti.nl/hvu
 

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