Mandos + CentOS 6

[Nathanael D. Noblet]

I haven't done anything else. It works but you can't use clients who've
linked to different versions of gnutls.

-- 
Nathanael

On Sun, 2014-06-29 at 23:43 +0200, Erik Logtenberg wrote:
> Hi,
> 
> Has there been any further progress on getting Mandos to work with
> RHEL/Fedora/CentOS?
> 
> Thanks,
> 
> Erik.
> 
> 
> On 04/13/2014 06:23 PM, Teddy Hogeborn wrote:
> > "Nathanael D. Noblet" <nathanael at gnat.ca> writes:
> > 
> >>>>> As far as I know, OpenSSL can not use OpenPGP keys, and at the
> >>>>> time I investigated, GnuTLS was the only TLS library to support
> >>>>> it.  I also seem to recall that OpenSSL has a problematic
> >>>>> license which precludes us from using it.
> >>>>
> >>>> So out of curiosity - why opengpg certificates + TLS?
> > [...]
> >>> The OpenPGP key serves an important security function.
> > [...]
> >>> For more details, see the section called NETWORK PROTOCOL in
> >>> mandos(8).
> >>>
> >>> I hope it is clear why conventional domain-name-based X.509
> >>> certificates would be completely inappropriate here.
> >>
> >> So I think I understand the above, however as far as I'm aware you can
> >> have two way verification of x.509 certificates. The server verifies
> >> the clients certificate and the client only provides its certificate
> >> to valid servers. Which essentially provides the same security as
> >> above.  With certificates signed by a trusted CA (which can be an in
> >> house CA).  The server makes sure that the certificate provided is
> >> trusted and then gets the client name from the certificate details
> >> (which can't be forged and still have a valid certificate if I'm not
> >> mistaken). I don't see much difference between that and the OpenPGP
> >> certificate method. Am I wrong?
> > 
> > No, I think your proposed scheme would basically work.  It has, however,
> > a few issues:
> > 
> > 1. Clients would need to arrange for their X.509 certificates to be
> >    signed by a CA which the Mandos server trusts.  This is an additional
> >    complication not needed with the existing protocol.
> > 
> > 2. You say that "[...] the client only provides its certificate to valid
> >    servers.".  Why?  This additional step could probably be added to the
> >    existing protocol, but what additional security does it provide?
> >    What attack does it prevent?
> > 
> > 3. Your proposed scheme uses X.509 certificates.  These are
> >    fundamentally unsuitable for our purposes due to:
> >    
> >    a) Their main orientation towards certificate authority signing
> >       chains.  We do not use this feature in Mandos, so there is every
> >       reason to prefer the simpler OpenPGP keys instead.
> >    
> >    b) The enormous complexity of X.509.  See here for more details:
> >       <https://www.cs.auckland.ac.nz/~pgut001/pubs/pkitutorial.pdf>
> >       This complexity has lead to very many bugs in a lot of software
> >       over the years, including Apple's recent "goto fail" bug.
> >    
> > 4. "GPG for data at rest. TLS for data in motion." is a rather well-
> >    known quote by Thomas Ptacek in a dialog he wrote about best
> >    practices in cryptography: <http://e-x-a.org/articles/typing-a-e-s/>
> >    If we want to follow that principle, we should encrypt the data with
> >    OpenPGP when it is "at rest" in the Mandos server.  This means the
> >    client needs an OpenPGP key *anyway* to decrypt this data.  So we
> >    already have an OpenPGP key to use in the TLS connection.  Using an
> >    additional X.509 certificate for the TLS connections seems
> >    nonsensical given that TLS already supports OpenPGP keys.
> > 
> > Also, we designed the protocol to use OpenPGP keys because we *like*
> > OpenPGP keys, and we wrote the program to use GnuTLS because we *like*
> > GnuTLS - and that is only partly because it supports OpenPGP keys in
> > TLS.
> > 
> > We have, so far, managed to avoid *all* major bugs in TLS libraries that
> > have been released in recent years.  We use GnuTLS, which is not subject
> > to the Heartbleed bug or to the "goto fail" bug, and the recent bug *in*
> > GnuTLS bug only affected verification of X.509 certificates.  Therefore,
> > I feel irrationaly pleased with our intuitive choices of technologies
> > and libraries.
> > 
> > /Teddy Hogeborn
> > 
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