what is GPG's #1 objective: security or anti-patent stance ( Re: on the state of PGP compatibility (2nd try))

[David Shaw]

On Mon, Apr 01, 2002 at 01:34:35AM +0100, Adam Back wrote:
> Hi
> 
> I've trimmed the Cc line a bit as this is now focussing more on GPG
> and not adding any thing new technically for the excluded set.
> 
> On Sun, Mar 31, 2002 at 06:08:14PM -0500, David Shaw wrote:
> > The OpenPGP spec handles compatibility issues quite well.  
> > The catch, of course, is that PGP 2.x isn't OpenPGP and PGP 5.x
> > isn't OpenPGP.  PGP 6 and 7 aren't really OpenPGP either, but
> > they're generally close enough for all practical purposes.
> 
> I don't see how this is a useful distinction.  They are self-evidently
> not close enough for practical purposes as evidenced by the fragmented
> user base and ongoing problems you experience if you try using PGP.

The fragmented user base is unfortunate.  Sometimes I almost wish that
PGP 5 had completely broken backwards compatibility with PGP 2 and
started clean.  At least then there would be no expectation of
compatibility.

I have spent hours upon hours poring over GnuPG messages, PGP 2
messages, PGP 6 messages and PGP 7 messages in an effort to reach the
one magical configuration that just plain *works*.  The sad fact is
that it is just not possible.  This shouldn't be surprising - version
n+1 of a computer program adding new features over version n.  Version
n then doesn't work with a version n+1 message.  It's a story as old
as computing.  OpenPGP fixes it by giving one spec for everyone to
follow, and by including a fairly rich syntax of "this is what I can
handle" notations in the keys.  It works quite well.  Problems tend to
arise mostly between the PGP6/PGP7/GnuPG and PGP2 worlds which OpenPGP
can't help of course.

Again, PGP 6 isn't OpenPGP, and neither is PGP 7 (though it is closer
than PGP 6).  I'm sure that PGP 8 would have followed OpenPGP even
more closely than PGP 7 did, but that doesn't look like it's going to
happen now.

GnuPG does follow OpenPGP.  It also has dozens of tricks and traps to
work around PGP behavior where PGP doesn't follow OpenPGP.  It even
(in GnuPG 1.0.7 (coming soon)) has a pgp2 and pgp6 modes to
"downgrade" messages it generates to what those versions of PGP can
handle (it can read messages from any version of course).

Since GnuPG can read a message from any version of PGP, and can
generate a message for any version of PGP (obviously doing a better
job of it the closer that version of PGP follows the OpenPGP spec),
and runs on your chosen platform (Linux), I think the real meat of
your complaint is in regards to the IDEA plugin:

> > I doubt it's intentionally hidden, though it's certainly a pain to
> > find.
> 
> I would characterise the situation as intentionally frustrating
> attempts to use IDEA.  The whole point of the little exercise of
> stripping out the idea.c, making it a separate dynamically loadable
> module, tucking it away in a FAQ where you are pointed to lectures
> about how software and algorithm patents are bad is _specifically, and
> explicitly_ to discourage use of patented algorithms (and in this case
> of the idea.c implementation) and to encourage people to do lobby
> about the patent madness.
> 
> Campaigning against patent madness is a good cause in itself but not
> when it gets in the way of privacy to the point that people are
> sending messages in plaintext.  After all what is GPG's primary
> purpose: is it an email security software package focussing on
> security, or a platform for promulgating political views.  I view the
> exclusion of idea.c from GPG as basically a security bug of higher
> severity than for example PGP2.x's manipulable fingerprint, or
> pgp5.something's (before it got fixed) unsigned ADK bug packet, or the
> potential buffer overflow in ZLIB.  This bug is worse because it
> reproducibly and frequently causes people to send mail in clear text.
> The other bugs are by comparison less dangerous, yet they (the two
> more recent ones) were fixed by NAI, and GPG and other PGP software
> maintainers with rushed over-night hot fixes.

I would not call this a bug.  A bug is a failure of the system to act
as described.  It is not a bug if the system annoys a user to the
point of not using the system :)

Still, yes, the IDEA plugin situation is far from ideal.  The bottom
line is that GPLed software can't use patented algorithms as it
contradicts the GPL.  It doesn't matter that the IDEA licence
basically allows free non-commercial use - it still contradicts the
GPL.

I would be quite happy if it became possible to include IDEA (maybe a
compile-time option?), but the reality is that IDEA is not required by
OpenPGP and every version of PGP from 5 onwards can communicate
without it.

David

-- 
   David Shaw  |  dshaw at jabberwocky.com  |  WWW http://www.jabberwocky.com/
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   "There are two major products that come out of Berkeley: LSD and UNIX.
      We don't believe this to be a coincidence." - Jeremy S. Anderson

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