> On Wed, 1 Aug 2001, John Walshe wrote:
>
> > Hi folks,
> >     I've just found an AutoCAD R13 dongle in the bottom of a box I got at a
> > factory clearout sale. It's one of those Rainbow Sentinel devices and I
> > can't tell what device is in it 'cos its a globbed die(it could be a pic ?)
> >
> > Anyone got and ideas as to how it works? Can I read/write it to and use it
> > to protect any of my own software?
> > I did a web trawl (a short one!) but came up blank. Has anyone got any info
> > on these things?


Hi John, the problem with hardware dongles is that
they generally use a hardware port like the parallel
port.

These can be cracked by any decent cracker, they just
search the executable file for code that accesses that
port. Once found it's pretty easy to identify the two
exit points for the dongle code, ie dongle failed/dongle
passed. Then they just put a goto to the dongle passed
exit. Dongle no longer needed... That's why you see so
many CAD programs hacked and available on the net
unfortunately.

If I used a dongle I would pass a byte TO the dongle,
use a PIC in the dongle which encrypts that byte and
passes it back to the PC as one or more bytes. Then in
your main code break that byte(s) up into various segments
and process/test it later at different points in your
code, eliminating the easy "dongle passed" test.
This won't stop them, but takes it to expert level
cracking rather than bored uni student level.

The best code protection I saw was a friends surveying
software costing $5000+ US. Each week the software
scanned their PC, generated a number and they have to
ring the main office and get a second number. Then
it works for a week. And nobody has ever cracked it
yet. :o)
-Roman

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