[zeromq-dev] TLS (openssl) for ZeroMQ

[Mark Botner]

I can confirm that ZeroMQ + Stunnel works extremely well.  Stunnel is very
robust - I'm using it to transfer many gigabytes / day over a 0MQ pub/sub
connection and have been doing so now for almost 2 years continuously.


Mark

On Fri, Dec 28, 2018 at 2:50 PM Trevor Bernard <trevor.bernard at gmail.com>
wrote:

> Why not just use stunnel as a TLS wrapper and avoid having to modify
> the zeromq code base? You are free to use OpenSSL, you don't need
> another key management system that can handle the Curve25519 elliptic
> curve. Configuration is likely easier than adding TLS support in
> ZeroMQ.
>
> On Wed, Dec 26, 2018 at 5:36 PM Jeff Shanab <jshanab at jfs-tech.com> wrote:
> >
> > In a lot of cases (mbtls) just don't link statically and the license
> issue is moot. But linking dynamically is preferred for more issues than
> license.
> >
> > I think there are a few things here to consider, and forgive me if I get
> the jargon wrong. There are other people here that are the experts.
> >
> > If you can use the OS implementation you can use their store, be ensured
> that the most recent security updates have been applied and a well
> optimized solution. (ok some of that may be up for debate, they have
> security updates becasue they are most attacked.)
> >
> > In some countries, even on windows, you just cannot legally use OpenSSL.
> So ability to swap it out is really good.
> > Some devices do not play nice and you really need to talk to them with
> an implementation they can work with (ie axis cameras vs ACTi cameras)
> >
> > If we write code into ZMQ that depends on a particular TLS
> implementation, we have done it wrong!
> >
> >
> >
> > On Wed, Dec 26, 2018 at 10:11 AM Luca Boccassi <luca.boccassi at gmail.com>
> wrote:
> >>
> >> There's also NSS from Mozilla which is under MPL and thus compatible,
> >> and does not introduce any restriction on third party code.
> >>
> >> There are then other less-known alternatives like wolfssl, mbed ssl or
> >> matrixssl which are all gpl2+ so cannot be used by proprietary products
> >> or static builds. But they all have commercial licenses available, so
> >> it can be used by your company for their product if they buy the
> >> license.
> >>
> >> On Tue, 2018-12-25 at 23:35 +0100, Luca Boccassi 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.com
> >> > > > 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 gmail
> >> > > > > > .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
> >>
> >> --
> >> 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
> _______________________________________________
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>
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