Re: storing an explicit nonce - Mailing list pgsql-hackers

Greetings,

* Bruce Momjian (bruce@momjian.us) wrote:
> On Thu, Oct  7, 2021 at 11:32:07PM -0400, Stephen Frost wrote:
> > Part of the meeting was specifically about "why are we doing this?" and
> > there were a few different answers- first and foremost was "because
> > people are asking for it", from which followed that, yes, in many cases
> > it's to satisfy an audit or similar requirement which any of the
> > proposed methods would address.  There was further discussion that we
>
> Yes, Cybertec's experience with their TDE patch's adoption supported
> this.
>
> > could address *more* cases by providing something better, but the page
> > format changes were weighed against that and the general consensus was
> > that we should attack the simpler problem first and, potentially, gain
> > a solution for 90% of the folks asking for it, and then later see if
> > there's enough interest and desire to attack the remaining 10%.
>
> It is more than just the page format --- it would also be the added
> code, possible performance impact, and later code maintenance to allow
> for are a more complex or two different page formats.

Yes, there is more to it than just the page format, I agree.  I'm still
of the mind that it's something we're going to get to eventually, if for
no other reason than that our current page format is certainly not
perfect and it'd be pretty awesome if we could make improvements to it
(independently of TDE or anything else discussed currently).

> As an example, I think the online checksum patch failed because it
> wasn't happy with that 90% and went for the extra 10% of restartability,
> but once you saw the 100% solution, the patch was too big and was
> rejected.

I'm, at least, still hopeful that we get the online checksum patch done.
I'm not sure that I agree that this was 'the' reason it didn't make it
in, but I don't think it'd be helpful to tangent this thread to
discussing some other patch.

> > As such, it's just not so simple as "what is 'secure enough'" because it
> > depends on who you're talking to.  Based on the collective discussion at
> > the meeting, XTS is 'secure enough' for the needs of probably 90% of
> > those asking, while the other 10% want better (an AEAD method such as
> > GCM or GCM-SIV).  Therefore, what should we do?  Spend all of the extra
> > resources and engineering effort to address the 10% and maybe not get
> > anything because of the level of difficulty, or go the simpler route
> > first and get the 90%?  Through that lense, the choice seemed reasonably
> > clear, at least to me, hence why I agreed that we should work on an XTS
> > based approach first.
>
> Yes, that was the conclusion.  I think it helped to have the discussion
> verbally with everyone hearing every word, rather than via email where
> people jump into the discussion not hearing earlier points.

Yes, agreed.  Certainly am hopeful that we are able to have more of
those in the (relatively) near future too!

Thanks!

Stephen