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PICList Thread
'Embedded System Protection'
1996\10\05@135804 by Miller, Steve

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Howdy All,

A friend of mine recently asked for my help in protecting an embedded
system of his from unauthorized duplication.  He has designed a 16 bit
embedded system that uses an external EEROM for program storage.  The PCB
is simple and easily copied, so he is worried that pirates will purchase
one of his units, make copies of the EEROM and duplicate his hardware,
thus selling clones of his design.  He has contacted me to help produce a
"code protection" microcontroller that would function like a "dongle".
Without this code protected PIC chip installed on the board, the units
would not function.

1.  How secure are the code protected PIC chips?

2.  Does any one have experience doing this?

3.  Should the PIC hold valuable "key parts" of his code?

I think this is a great use for a PIC chip and great opportunity for PIC
programmers to make some money providing unique system protection chips.
Please let me know your thoughts.

---- Steve

spam_OUTstevemTakeThisOuTspamtanisys.com

1996\10\05@152706 by Jeff Otterson/N1KDO

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>A friend of mine recently asked for my help in protecting an embedded
>system of his from unauthorized duplication.  He has designed a 16 bit
>embedded system that uses an external EEROM for program storage.  The PCB


Maybe he can use a GAL do to his address decoding, and read-protect the GAL.
That method has been used by more than one vendor that I am aware of...

Jeff Otterson
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.....ottersonKILLspamspam@spam@mindspring.com
Maker and user of tools
PGP key available at http://www.mindspring.com/~otterson/pgp.htm

1996\10\05@174949 by Piotr Piatek

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Jeff Otterson/N1KDO <ottersonspamKILLspamMINDSPRING.COM> wrote:

> Maybe he can use a GAL do to his address decoding, and read-protect the
GAL.
> That method has been used by more than one vendor that I am aware of...

Protected GALs can be easy copied without reading the devices' fuse
map. It's especially easy in case of an address decoder, where no latches
are used and there is one-to-one assignment between input and output
values. I've done this several times (for replacing defective parts, not
for stealing somebody's code !). I've read the truth table of the chip with
an EPROM programmer, then reduced it and converted to a CUPL source
file using a program written in C.

- Piotr

Piotr Piatek    .....pisielekKILLspamspam.....inet.com.pl

1996\10\05@191130 by John Payson

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> Jeff Otterson/N1KDO <EraseMEottersonspam_OUTspamTakeThisOuTMINDSPRING.COM> wrote:
> > Maybe he can use a GAL do to his address decoding, and read-protect the
> GAL.
> > That method has been used by more than one vendor that I am aware of...
>
> Protected GALs can be easy copied without reading the devices' fuse
> map. It's especially easy in case of an address decoder, where no latches
> are used and there is one-to-one assignment between input and output
> values.

Reading out a protected GAL in which there are no latches is trivial; on
GALs with latches things may be harder but if no latches are buried it's
still easy.  Reading out a GAL with buried latches may be a little bit
difficult, but since at most 9 latches may be buried in a 22V10 that does
anything useful I would not expect this to be any more than 512 times as
hard as reading one with no buried latches (which I would expect to be
fully automatic).

1996\10\07@101703 by Shawn Ellis
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>
> 1.  How secure are the code protected PIC chips?
>
Oh no, not this again...

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