Re: Add "password_protocol" connection parameter to libpq

On Fri, Aug 16, 2019 at 02:11:57PM -0400, Jonathan S. Katz wrote:
> To be pedantic, +1 on the channel_binding param.

Seems like we are moving in this direction then.  I don't object to
the introduction of this parameter.  We would likely want to do
something for downgrade attacks in other cases where channel binding
is not used, still there is verify-ca/full even in this case which
offer similar protections for MITM and eavesdropping.

> I would ask if scram-sha-256-plus makes the list if we have the
> channel_binding param?

No in my opinion.

> If channel_binding = require, it would essentially ignore any non-plus
> options in password_protocol and require scram-sha-256-plus. In a future
> scram-sha-512 world, then having scram-sha-256-plus or
> scram-sha-512-plus options in "password_protocol" then could be
> necessary based on what the user would prefer or require in their
> application.

Not including scram-sha-512-plus or scram-sha-256-plus in the
comma-separated list would be a problem for users willing to give for
example scram-sha-256,scram-sha-512-plus as an authorized list of
protocols but I don't think that it makes much sense as they basically
require an SSL connection for tls-server-end-point per the second
element.
--
Michael