crypto hardware (was Re: more protocols...)

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On Mon, Jan 13, 2003 at 09:36:49AM +1100, Michael Davidson wrote:
> Also I'm pretty sure that you could find an IC that performs DES or some 
> other encryption routine if you have a look around - if not, I'm sure Sony 
> could have made one pretty easily

There does indeed exist cheap commodity hardware of the sort you describe,
and Sony is certainly capable of acquiring it (by any means up to and
including building it from the ground up).

I have detailed pictures of the innards of my MZ-N707 here:
   http://kharendaen.dyndns.org:8000/~henke/public/mz-n707/
if anyone with a strong hardware background feels like playing a little
game of "spot the custom crypto processor".

My first guess is that they're just doing it in software using the
general-purpose microprocessor already on board. This would certainly
be the cheapest way to go (and pennies matter on consumer devices like
this) and may save power as well. It also means you can fix bugs (or add
further sneaky DRM "features") with a firmware update. (It would also
imply that this project might make some real progress if we can bogart
a copy of the firmware. Much easier to disassemble that than custom
silicon.)

My second guess would be that any custom hardware would be on the same
die as the CPU. I seem to recall one of the ideas of the ARM core is
that you could add application-specific bits (including custom ones)
as needed, like building blocks. That lets you do it "in hardware"
without adding to the parts count or consuming more board real estate.
But they'd only do this if they _had_ to do something that would take
too much time or power to do in the general-purpose CPU (and if they
couldn't change the algorithm to eliminate the need for custom hardware).

> DES was made to be easy to perform in hardware, if I recall correctly.

You recall correctly. I doubt it's DES, though -- lots of other crypto
out there which translates well to silicon, without the obvious weaknesses
of DES.

Happy hacking,
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