Re: Add "password_protocol" connection parameter to libpq

On Tue, 2019-08-13 at 16:51 -0400, Jonathan S. Katz wrote:
> Alternatively, we could combine 2 & 3, e.g.:
> 
>   channel_binding = {disable|prefer|require}
> 
>   # comma-separated list of protocols that are ok to the user, remove
>   # ones you don't want. empty means all is ok
>   password_protocol = "plaintext,md5,scram-sha-256,scram-sha-256-
> plus"

I still feel like lists are over-specifying things. Let me step back
and offer an MVP of a single new parameter:

  channel_binding={prefer|require}

And has a lot of benefits:
    * solves the immediate need to make channel binding useful, which
is a really nice feature
    * compatible with most of the other proposals we're considering, so
we can always extend it when we have a better understanding and
consensus
    * clear purpose for the user
    * doesn't introduce new concepts that might be confusing to the
user, like SASL or the use of "-plus" to mean "with channel binding"
    * guides users toward the good practice of using SSL and SCRAM
    * simple to implement

The other use cases are less clear to me, and seem less urgent.

Regards,
    Jeff Davis