the public key minefield

[Peter Baumbach]

> The question is phrased improperly.  Apart from the fact that the
> concept (though not the reality) of anti-gravity is prior art, they
> didn't patent the concept of public-key cryptography.  Rather, they
> patented a class of devices fitting a certain description, with one
> public key cryptosystem as an example and as a separate set of claims.
> To use your analogy, I could patent anti-gravity achieved by interposing
> a screen of some substance opaque to gravity, and patent Cavorite as
> an instance of that class.  If you had another use for Cavorite, you'd
> be home free.  Or if you found a way to neutralize gravity by beaming
> anti-gravitons downward, you'd probably be clear, too.  But if you
> found another substance besides Cavorite that was opaque to gravity --
> yes, that would be covered by my patent.  (Fortunately, H.G. Wells didn't
> patent his literary device.  But I can't think of another science
> fiction author who used that technique....)
> 
> It's certainly possible that all possible cryptosystems that achieve the
> same effect would be covered by their description.  That, of course, is
> the mark of a good patent attorney's work -- that he or she managed to
> fashion so broad a claim.  But maybe you can find a better way to do what
> you really want to do, which is trade keys and authenticate messages.

I think you have convinced me.  I don't want to be convinced, so maybe I
will try again later, when I have learned more about it. ;-)

This means to me, that you cannot patent a broad claim, until you have a
narrow specific example of it.  Anti-gravity had prior art, public key
systems did not.  If without inventing a public key system, someone had
described the concept in general terms, then prior art would exist for
this as well.  The person who invented the wheel (or sled?) might have
been able to have claims broad enough to cover hovercrafts.

> And if you do -- well, then, the patent system has succeeded in its goals,
> in that the monopoly assigned to someone else has stimulated you to find
> another way to do things, and thus furthered the useful arts and sciences.

At what expense?  Will our government win some battles, it might otherwise
lose to the cypherpunks?  Would legal access to pgp, now, be a deciding
factor to maintaining legal access to non-clipper encryption later?

Peter Baumbach
baumbach at atmel.com