notes

早期freebsd实现

From: James A. Woods <[e-mail]>

>From vn Fri Dec  2 18:05:27 1988
Subject: Re: Looking for C source for RSA
Newsgroups: sci.crypt

# Illegitimi noncarborundum

Patents are a tar pit.

A good case can be made that most are just a license to sue, and nothing
is illegal until a patent is upheld in court.

For example, if you receive netnews by means other than 'nntp',
these very words are being modulated by 'compress',
a variation on the patented Lempel-Ziv-Welch algorithm.

Original Ziv-Lempel is patent number 4,464,650, and the more powerful
LZW method is #4,558,302.  Yet despite any similarities between 'compress'
and LZW (the public-domain 'compress' code was designed and given to the
world before the ink on the Welch patent was dry), no attorneys from Sperry
(the assignee) have asked you to unplug your Usenet connection.

Why?  I can't speak for them, but it is possible the claims are too broad,
or, just as bad, not broad enough.  ('compress' does things not mentioned
in the Welch patent.)  Maybe they realize that they can commercialize
LZW better by selling hardware implementations rather than by licensing
software.  Again, the LZW software delineated in the patent is *not*
the same as that of 'compress'.

At any rate, court-tested software patents are a different animal;
corporate patents in a portfolio are usually traded like baseball cards
to shut out small fry rather than actually be defended before
non-technical juries.  Perhaps RSA will undergo this test successfully,
although the grant to "exclude others from making, using, or selling"
the invention would then only apply to the U.S. (witness the 
Genentech patent of the TPA molecule in the U.S. but struck down
in Great Britain as too broad.)

The concept is still exotic for those who learned in school the rule of thumb
that one may patent "apparatus" but not an "idea".
Apparently this all changed in Diamond v. Diehr (1981) when the U. S. Supreme
Court reversed itself.  

Scholars should consult the excellent article in the Washington and Lee
Law Review (fall 1984, vol. 41, no. 4) by Anthony and Colwell for a
comprehensive survey of an area which will remain murky for some time.

Until the dust clears, how you approach ideas which are patented depends
on how paranoid you are of a legal onslaught.  Arbitrary?  Yes.  But
the patent bar the the CCPA (Court of Customs and Patent Appeals)
thanks you for any uncertainty as they, at least, stand to gain
from any trouble.

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From: James A. Woods <[e-mail]>
Subject: Re: Looking for C source for RSA (actually 'compress' patents)

	In article <[e-mail]> you write:
	>The concept is still exotic for those who learned in school the rule of thumb
	>that one may patent "apparatus" but not an "idea".

A rule of thumb that has never been completely valid, as any chemical
engineer can tell you.  (Chemical processes were among the earliest patents,
as I recall.)

	ah yes -- i date myself when relaying out-of-date advice from elderly
	attorneys who don't even specialize in patents.  one other interesting
	class of patents include the output of optical lens design programs,
	which yield formulae which can then fairly directly can be molded
	into glass.  although there are restrictions on patenting equations,
	the "embedded systems" seem to fly past the legal gauntlets.

	anyway, i'm still learning about intellectual property law after
	several conversations from a unisys (nee sperry) lawyer re 'compress'.

	it's more complicated than this, but they're letting (oral
	communication only) software versions of 'compress' slide
	as far as licensing fees go.  this includes 'arc', 'stuffit',
	and other commercial wrappers for 'compress'.  yet they are
	signing up licensees for hardware chips.  hewlett-packard
	supposedly has an active vlsi project, and unisys has
	board-level lzw-based tape controllers.  (to build lzw into
	a disk controller would be strange, as you'd have to build
	in a filesystem too!)

 	it's byzantine
	that unisys is in a tiff with hp regarding the patents,
	after discovering some sort of "compress" button on some
	hp terminal product.  why?  well, professor abraham lempel jumped
	from being department chairman of computer science at technion in
	israel to sperry (where he got the first patent), but then to work
	at hewlett-packard on sabbatical.  the second welch patent
	is only weakly derivative of the first, so they want chip
	licenses and hp relented.  however, everyone agrees something
	like the current unix implementation is the way to go with
	software, so hp (and ucb) long ago asked spencer thomas and i to sign
	off on copyright permission (although they didn't need to, it being pd).
	lempel, hp, and unisys grumbles they can't make money off the
	software since a good free implementation (not the best --
	i have more ideas!) escaped via usenet.  (lempel's own pascal
	code was apparently horribly slow.)
	i don't follow the ibm 'arc' legal bickering; my impression
	is that the pc folks are making money off the archiver/wrapper
	look/feel of the thing [if ms-dos can be said to have a look and feel]. 

	now where is telebit with the compress firmware?  in a limbo
	netherworld, probably, with sperry still welcoming outfits
	to sign patent licenses, a common tactic to bring other small fry
	into the fold.  the guy who crammed 12-bit compess into the modem
	there left.  also what is transpiring with 'compress' and sys 5 rel 4?
	beats me, but if sperry got a hold of them on these issues,
	at&t would likely re-implement another algorithm if they
	thought 'compress' infringes.  needful to say, i don't think
	it does after the abovementioned legal conversation.
	my own beliefs on whether algorithms should be patentable at all
	change with the weather.  if the courts finally nail down
	patent protection for algorithms, academic publication in
	textbooks will be somewhat at odds with the engineering world,
	where the textbook codes will simply be a big tease to get
	money into the patent holder coffers...

	oh, if you implement lzw from the patent, you won't get
	good rates because it doesn't mention adaptive table reset,
	lack thereof being *the* serious deficiency of thomas' first version.

	now i know that patent law generally protects against independent
	re-invention (like the 'xor' hash function pleasantly mentioned
	in the patent [but not the paper]).
	but the upshot is that if anyone ever wanted to sue us,
	we're partially covered with
	independently-developed twists, plus the fact that some of us work
	in a bureacratic morass (as contractor to a public agency in my case).

	quite a mess, huh?  i've wanted to tell someone this stuff
	for a long time, for posterity if nothing else.

james