Re: [Proposal] Table-level Transparent Data Encryption (TDE) and KeyManagement Service (KMS)

On Wed, Jul 10, 2019 at 02:57:54PM -0400, Stephen Frost wrote:
> Greetings,
> 
> * Ryan Lambert (ryan@rustprooflabs.com) wrote:
> > > I didn't either, except it was referenced above as "forward hash".  I
> > > don't know why that was suggested, which is why I listed it as an
> > > option/suggestion.
> > 
> > My bad, sorry for the confusion!  I meant to say "cipher" not "hash".  I
> > was (trying to) refer to the method of generating unpredictable IV from
> > nonces using the forward cipher function and the encryption key.
> > Too many closely related words with very specific meanings.
> 
> No worries, just want to try and be clear on these things..  Too easy to
> mistakenly think that doing this very-similar-thing will be as secure as
> doing the recommended-thing (particularly when the recommended-thing is
> a lot harder...), and we don't want to end up doing that and then
> discovering it isn't actually secure..

Good, so I think we all now agree we have to put the nonce
(pg_class.oid, LSN, page-number) though the cipher using the secret.  I
think Stephen is right that the overhead of this will be minimal for 8k
page writes, and for WAL, we only need to generate the IV when we start
a new 16MB segment, so again, minimal overhead.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
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