Alex Kilpatrick wrote:
>
> >The way the military does this sort of thing is to blow the IC's up
> >with a small electrically detonated explosive charge, on their
> >Cryptographic systems, I've heard.  That tends to stop people from
> >poking in the innards of such systems, but it's hard to do for us
> >non-military designers!  There are a lot of tricks (I remember some, not
> >my area of expertise...)
> >
>
> The device is called a squib.  Here's a sample warning page for one:
> http://www.amerex-fire.com/msds/long/m1squibv.html
>
> I imagine you could roll-your-own squib, but you might have a hard time with
> the consumer products safety commission. :-)
>
> However, I am curious just how valuable the code in a PIC could be.  After
> all, we are only talking about 1K of assembler, not something like windows
> 95 or anything.  It seems like the real commercial advantage is product
> design and marketing, not in the particular code in a PIC.  After all, it
> seems like given an arbitrary product with a PIC in it, I could just write
> code to do whatever the PIC does, without having to resort to bypassing the
> code-protect bit.
>
> Alex

  In their case, they are making a widget that will make them a lot of
money, they want to avoid anyone else being able to reverse-engineer
what they're doing.

  As I know the algorithm used to do what they want done, it should be
possible to do it in a PIC (an overclocked one, probably!) or two - It
wouldn't be easy to reverse engineer it though, I don't think.  It's
going to stretch MY brain <G>

  (They're fortunate in that it's going to sit at their facility - so I
suggested they just pull the card out & lock it up at night if they're
really bothered.  Or blow it up from a big cap if disturbed.)

  A thought - how would you reverse-engineer, say, a Radio Shack Li-Ion
charger, knowing only the parts used - if you knew it was a battery
charger, but you'd never built one before - didn't know how they worked
- and knew a little about Li-Ion batteries but didn't really know enough
to do it?  That sort of situation (Not that particular one, of course,
but that flavor of situation) where it's do-able but the algorithm is
proprietary, and IS valuable, would be good candidates for code
protection (Depends on what you want, whether you use it or not.)
Things where timing is important & you're running flat out at full speed
on the PIC, are IMHO harder to reverse-engineer <G>

  Squibs, Thermite, Mechanical crushers, drop 117 VAC across the
oscillator pins, all kinds of easy ways to break electronics <G>

  Mark, mwillis@nwlink.com