>Yes, it is that cheap (and easy) to find and read efuses. If they had
>used Actel's via fuse technology, it would be much, much harder, but
>still do-able for a small number of vias. Of course, you would have to
>know where to look. The poly efuse is huge, and is almost big enough to
>see with the eye. An array of 128, or 256 has a big sign on it: "efuse
>array right here!"

Whenever I get involved with a discussion like this, I point people
at these papers:
http://www.cl.cam.ac.uk/~mgk25/sc99-tamper.pdf
http://www.cl.cam.ac.uk/~mgk25/sc99-tamper-slides.pdf

That's from 1999. Still a great read.

The details have changed, but I doubt if the general idea is out of
date. People who build chips have to debug them. They will keep the
technology up to date.

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