[zeromq-dev] TLS (openssl) for ZeroMQ

Luca Boccassi luca.boccassi at gmail.com
Sat Dec 29 20:27:33 CET 2018 

That's a bit strange given only in Debian there are like a thousand
packages depending on it, including things like apt, so most distros
most likely already have it

On Sat, 2018-12-29 at 08:44 +0100, 林宝龙 wrote:
> Similar reason as curve, the product environment doesn't have gnutls
> installed, new security library need to be installed if choose
> gnutls.
> 
> Best regards,
> Baolong
> 
> On Tue, 25 Dec 2018, 23:37 Luca Boccassi <luca.boccassi at gmail.com
> wrote:
> 
> > Note that as an alternative to openssl there's gnutls which is
> > lgpl2+ and
> > thus is compatible - but only for dynamic linking, proprietary
> > applications
> > statically linking to libzmq thanks to it's exception will not be
> > able to
> > statically link to gnutls.
> > 
> > On Tue, 25 Dec 2018, 21:13 Luca Boccassi <luca.boccassi at gmail.com
> > wrote:
> > 
> > > On Tue, 2018-12-25 at 21:05 +0100, 林宝龙 wrote:
> > > > I suggested to use curve directly, but as a hole system, they
> > > > didn't
> > > > want
> > > > to have two key management system, TLS was there which was used
> > > > by
> > > > other
> > > > node. And another reason they gave to me is the curve was not
> > > > been
> > > > used so
> > > > much by big companies compare to TLS, even it's simple than
> > > > TLS.
> > > > Further
> > > > more the running environment has already had OpenSSL installed,
> > > > use
> > > > openssl
> > > > can lower the security libraries maintenance.
> > > 
> > > First of all curve was created by expert cryptographers, and it's
> > > extensively used, so it's not really a problem. The crypto
> > > primitives
> > > are provides by libsodium, which again is a very high quality
> > > library
> > > and used by many, many applications and libraries, and will most
> > > likely
> > > be already installed everywhere.
> > > 
> > > Regarding key management, are you aware that there's the ZAP
> > > protocol?
> > > You can use it to implement the key management scheme you prefer,
> > > programmatically. For example, you could map 1:1 from SSL keys to
> > > curve
> > > keys internally.
> > > 
> > > > About the license problem, as you explained to me, it is a big
> > > > problem, I
> > > > saw there is an issue which was registered 2 years ago to
> > > > change the
> > > > libzmq's license, but it is not coming to end. I'll check with
> > > > my
> > > > colleagues how to make the license issue gone?  Come back to
> > > > you when
> > > > I
> > > > have more information.
> > > 
> > > Again - you *cannot* make the license issue go away. We have been
> > > trying to relicense to MPL2 for years, it will take years to
> > > finish, if
> > > ever. This is not something that can be worked around or
> > > "hacked". It's
> > > a legal issue.
> > > 
> > > > Best regards,
> > > > Baolong
> > > > 
> > > > On Tue, 25 Dec 2018, 12:31 Luca Boccassi <luca.boccassi at gmail.c
> > > > om
> > > > wrote:
> > > > 
> > > > > On Tue, 2018-12-25 at 00:53 +0100, 林宝龙 wrote:
> > > > > > The problem of first option we met is that OpenSSL provides
> > > > > > a lot
> > > > > > configurable things, for example, trust group, external
> > > > > > verification
> > > > > > callback, etc. We must add more options to sockopt to have
> > > > > > such
> > > > > > things
> > > > > > configurable. For the callback functions, if we continue
> > > > > > using
> > > > > > setsockopt,
> > > > > > we need to cast function pointer to void pointer and vice
> > > > > > versa,
> > > > > > looks not
> > > > > > good.
> > > > > 
> > > > > As mentioned, there is really no alternative to continue
> > > > > supporting
> > > > > bindings. Also, exposing a third party API/ABI again would
> > > > > mean
> > > > > that
> > > > > the users would need to start worrying about OpenSSL's
> > > > > API/ABI
> > > > > changes,
> > > > > and keep them in sync with the internal usage of the library.
> > > > > That
> > > > > would not be maintainable.
> > > > > 
> > > > > So it looks like there are both legal and implementation
> > > > > problems.
> > > > > So
> > > > > let's take a step back: why is the current
> > > > > encryption/authentication
> > > > > support via CURVE and GSSAPI not sufficient? What is lacking
> > > > > that
> > > > > you
> > > > > need in your application?
> > > > > 
> > > > > > About the licence issue, I'm not familiar with those
> > > > > > licenses,
> > > > > > and I
> > > > > > have
> > > > > > asked someone inside my company, got the answer that I can
> > > > > > use
> > > > > > OpenSSL in
> > > > > > libzmq with an exception, I don't know how. He said that we
> > > > > > will
> > > > > > share the
> > > > > > code out in the end, but can't contribute back to libzmq
> > > > > > directly.
> > > > > > Does it
> > > > > > same as what you concern? Do you have more information that
> > > > > > we
> > > > > > must
> > > > > > stop
> > > > > > using OpenSSL inside libzmq?
> > > > > 
> > > > > Yes an exception is needed as I said, but not just from you:
> > > > > from
> > > > > every
> > > > > single copyright holder of libzmq, of which there are many.
> > > > > That's
> > > > > because adding an exception to the license is a change in
> > > > > license,
> > > > > and
> > > > > cannot legally be done unilaterally.
> > > > > 
> > > > > Note that this is not only a problem for contributing code
> > > > > back,
> > > > > but
> > > > > also for your application. You cannot distribute those
> > > > > changes to
> > > > > anybody without a license change, which means you cannot give
> > > > > your
> > > > > application to anybody without breaching the terms of the
> > > > > license,
> > > > > and
> > > > > thus copyright law.
> > > > > 
> > > > > > On Mon, 24 Dec 2018, 23:42 Luca Boccassi <luca.boccassi at gma
> > > > > > il.com
> > > > > > wrote:
> > > > > > 
> > > > > > > On Mon, 24 Dec 2018, 23:03 林宝龙 <lbl52001 at gmail.com wrote:
> > > > > > > 
> > > > > > > > Hi,
> > > > > > > > 
> > > > > > > > We are adding TLS support for ZeroMQ(based on 4.2.5).
> > > > > > > > Product
> > > > > > > > reason, we
> > > > > > > > choosed OpenSSL as TLS library.
> > > > > > > > 
> > > > > > > > Ask community for suggestions, which solution below is
> > > > > > > > better?
> > > > > > > > 1. Use TLS public certification, private key, etc as
> > > > > > > > socket
> > > > > > > > option (set
> > > > > > > > through setsockopt), ZeroMQ manages the OpenSSL
> > > > > > > > context,
> > > > > > > > one  OpenSSL
> > > > > > > > context per socket_base_t object.
> > > > > > > > 2. Use OpenSSL context as socket option(set through
> > > > > > > > setsockopt),
> > > > > > > > external
> > > > > > > > application should provide the OpenSSL context, with
> > > > > > > > public
> > > > > > > > certification,
> > > > > > > > private key, etc. set in context level, all ssl
> > > > > > > > connections
> > > > > > > > share
> > > > > > > > the same
> > > > > > > > configuration as the input OpenSSL context.
> > > > > > > > 
> > > > > > > > At beginning we choosed the first solution, like curve,
> > > > > > > > use
> > > > > > > > public
> > > > > > > > certification, private key as the socket option. But
> > > > > > > > later
> > > > > > > > on, we
> > > > > > > > found the
> > > > > > > > second solution that use external OpenSSL context can
> > > > > > > > make
> > > > > > > > the
> > > > > > > > ZeroMQ code
> > > > > > > > simpler, and more flexible, external application can
> > > > > > > > configure
> > > > > > > > the OpenSSL
> > > > > > > > context without change the ZeroMQ socket options.
> > > > > > > > 
> > > > > > > > Welcome your comments.
> > > > > > > > 
> > > > > > > > Best regards,
> > > > > > > > Baolong
> > > > > > > > 
> > > > > > > 
> > > > > > > The first option would be better, exposing third party
> > > > > > > API and
> > > > > > > ABI
> > > > > > > would
> > > > > > > be a nightmare, especially for bindings. O
> > > > > > > 
> > > > > > > But the most important issue is that the Openssl license
> > > > > > > is not
> > > > > > > compatible
> > > > > > > with libzmq, which is licensed under the lgpl3, so I'm
> > > > > > > afraid
> > > > > > > such
> > > > > > > combination will not be legally distributable. At least
> > > > > > > not
> > > > > > > without
> > > > > > > a
> > > > > > > relicensing effort to add an exception - we are already
> > > > > > > trying
> > > > > > > that
> > > > > > > to
> > > > > > > change to mpl2 and are nowhere near done unfortunately.
> > > > > > > 
> > > > > > > > _______________________________________________
> > > > > > > 
> > > > > > > zeromq-dev mailing list
> > > > > > > zeromq-dev at lists.zeromq.org
> > > > > > > https://lists.zeromq.org/mailman/listinfo/zeromq-dev
> > > > > > > 
> > > > > > 
> > > > > > _______________________________________________
> > > > > > zeromq-dev mailing list
> > > > > > zeromq-dev at lists.zeromq.org
> > > > > > https://lists.zeromq.org/mailman/listinfo/zeromq-dev
> > > > > 
> > > > > --
> > > > > Kind regards,
> > > > > Luca Boccassi_______________________________________________
> > > > > zeromq-dev mailing list
> > > > > zeromq-dev at lists.zeromq.org
> > > > > https://lists.zeromq.org/mailman/listinfo/zeromq-dev
> > > > > 
> > > > 
> > > > _______________________________________________
> > > > zeromq-dev mailing list
> > > > zeromq-dev at lists.zeromq.org
> > > > https://lists.zeromq.org/mailman/listinfo/zeromq-dev
> > > 
> > > --
> > > Kind regards,
> > > Luca Boccassi
> > 
> > _______________________________________________
> > zeromq-dev mailing list
> > zeromq-dev at lists.zeromq.org
> > https://lists.zeromq.org/mailman/listinfo/zeromq-dev
> > 
> 
> _______________________________________________
> zeromq-dev mailing list
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-- 
Kind regards,
Luca Boccassi
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