On Thu, May 17, 2018 at 09:48:54PM +0900, Michael Paquier wrote:
> On Wed, May 16, 2018 at 09:09:22PM -0400, Bruce Momjian wrote:
> > On Thu, May 17, 2018 at 09:56:49AM +0900, Michael Paquier wrote:
> >> On Wed, May 16, 2018 at 08:20:49PM -0400, Bruce Momjian wrote:
> >>> SCRAM-with-binding is the first password method that attempts to avoid
> >>> man-in-the-middle attacks, and therefore is much less likely to be able
> >>> to trust what the endpoints supports.  I think it is really the
> >>> channel_binding_mode that we want to control at the client.  The lesser
> >>> modes are much more reasonable to use an automatic best-supported
> >>> negotiation, which is what we do now.
> >> 
> >> Noted.  Which means that the parameter is ignored when using a non-SSL
> >> connection, as well as when the server tries to enforce the use of
> >> anything else than SCRAM.
> > 
> > Uh, a man-in-the-middle could prevent SSL or ask for a different
> > password authentication method and then channel binding would not be
> > used.  I think when you say you want channel binding, you have to fail
> > if you don't get it.
> I am not exactly sure what is the result we are looking for here, so I
> am adding for now an open item which refers to this part of the thread.
> Please note that I am fine to spend cycles if needed to address any
> issues and/or concerns.  Let's the discussion continue for now.

Agreed, and I just posted a more detailed email about when
authentication downgrades are possible.

  Bruce Momjian  <br...@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

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