Re: Password identifiers, protocol aging and SCRAM protocol

On Sun, Jul 3, 2016 at 4:54 AM, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
> I took a quick look at the patch set now again, and except that it needs to
> have the multiple password verifier support refactored out, I think it's in
> a pretty good shape. I don't like the pg_upgrade changes and its support
> function, that also seems like an orthogonal or add-on feature that would be
> better discussed separately. I think pg_upgrade should just do the upgrade
> with as little change to the system as possible, and let the admin
> reset/rehash/deprecate the passwords separately, when she wants to switch
> all users to SCRAM. So I suggest that we rip out those changes from the
> patch set as well.

That's as well what I recall from the consensus at PGCon: only focus
on the protocol addition and storage of the scram verifier. It was not
mentioned directly but that's what I guess should be done. So no
complains here.

> In related news, RFC 7677 that describes a new SCRAM-SHA-256 authentication
> mechanism, was published in November 2015. It's identical to SCRAM-SHA-1,
> which is what this patch set implements, except that SHA-1 has been replaced
> with SHA-256. Perhaps we should forget about SCRAM-SHA-1 and jump straight
> to SCRAM-SHA-256.

That's to consider. I don't thing switching to that is much complicated.

> RFC 7677 also adds some verbiage, in response to vulnerabilities that have
> been found with the "tls-unique" channel binding mechanism:
>
>> To be secure, either SCRAM-SHA-256-PLUS and SCRAM-SHA-1-PLUS MUST be
>> used over a TLS channel that has had the session hash extension
>> [RFC7627] negotiated, or session resumption MUST NOT have been used.
>
> So that doesn't affect details of the protocol per se, but once we implement
> channel binding, we need to check for those conditions somehow (or make sure
> that OpenSSL checks for them).

Yes.

> Michael, do you plan to submit a new version of this patch set for the next
> commitfest? I'd like to get this committed early in the 9.7 release cycle,
> so that we have time to work on all the add-on stuff before the release.

Thanks. That's good news! Yes, I am still on track to submit a patch for CF1.
--
Michael