Horton

Re: storing an explicit nonce

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Stephen Frost <sfrost@snowman.net>
Cc: Ants Aasma <ants@cybertec.at>, Sasasu <i@sasa.su>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-10-07T19:11:26Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Rethink method for assigning OIDs to the template0 and postgres DBs.

  2. pg_upgrade: Preserve database OIDs.

  3. pg_upgrade: Preserve relfilenodes and tablespace OIDs.

  4. Fix for new Boolean node

  5. Improve error handling of HMAC computations

  6. Add macro RelationIsPermanent() to report relation permanence

  7. Enhance nbtree index tuple deletion.

On Thu, Oct  7, 2021 at 02:52:07PM -0400, Stephen Frost wrote:
> > > Is there a particular reason why you would prefer not to use LSN? I suggested
> > > it because in my view having a variable tweak is still better than not having
> > > it even if we deem the risks of XTS tweak reuse not important for our use case.
> > > The comment was made under the assumption that requiring wal_log_hints for
> > > encryption is acceptable.
> > 
> > Well, using the LSN means we have to store the LSN unencrypted, and that
> > means we have to carve out a 16-byte block on the page that is not
> > encrypted.
> 
> With XTS this isn't actually the case though, is it..?  Part of the
> point of XTS is that the last block doesn't have to be a full 16 bytes.

> What you're saying is true for XEX, but that's also why XEX isn't used
> for FDE in a lot of cases, because disk sectors aren't typically
> divisible by 16.

Oh, I was not aware of that XTS feature.  Nice.

> https://en.wikipedia.org/wiki/Disk_encryption_theory
> 
> Assuming that's correct, and I don't see any reason to doubt it, then
> perhaps it would make sense to have the LSN be unencrypted and include
> it in the tweak as that would limit the risk from re-use of the same
> tweak over time.

Yes, seems like a plan.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  If only the physical world exists, free will is an illusion.