Re: better page-level checksums

On Tue, Jun 14, 2022 at 01:42:55PM -0400, Robert Haas wrote:
> Hmm, but on the other hand, if you imagine a scenario in which the
> "storage system extra blob" is actually a nonce for TDE, you need to
> be able to find it before you've decrypted the rest of the page. If
> pd_checksum gives you the offset of that data, you need to exclude it
> from what gets encrypted, which means that you need encrypt three
> separate non-contiguous areas of the page whose combined size is
> unlikely to be a multiple of the encryption algorithm's block size.
> That kind of sucks (and putting it at the end of the page makes it way
> better).

I continue to believe that a nonce is not needed for XTS encryption
mode, and that adding a tamper-detection GCM hash is of limited
usefulness since malicious writes can be done to other critical files
and can be used to find the cluster or encryption keys

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

  Indecision is a decision.  Inaction is an action.  Mark Batterson