On Tue, Oct 12, 2021 at 08:25:52AM -0400, Stephen Frost wrote: > Greetings, > > * Bruce Momjian (br...@momjian.us) wrote: > > On Tue, Oct 12, 2021 at 08:40:17AM +0300, Ants Aasma wrote: > > > On Mon, 11 Oct 2021 at 22:15, Bruce Momjian <br...@momjian.us> wrote: > > > > > > > Yes, that's the direction that I was thinking also and specifically > > > with > > > > XTS as the encryption algorithm to allow us to exclude the LSN but > > > keep > > > > everything else, and to address the concern around the > > > nonce/tweak/etc > > > > being the same sometimes across multiple writes. Another thing to > > > > consider is if we want to encrypt zero'd page. There was a point > > > > brought up that if we do then we are encrypting a fair bit of very > > > > predictable bytes and that's not great (though there's a fair bit > > > about > > > > our pages that someone could quite possibly predict anyway based on > > > > table structures and such...). I would think that if it's easy > > > enough > > > > to not encrypt zero'd pages that we should avoid doing so. Don't > > > recall > > > > offhand which way zero'd pages were being handled already but > > > thought it > > > > made sense to mention that as part of this discussion. > > > > > > Yeah, I wanted to mention that. I don't see any security difference > > > between fully-zero pages, pages with headers and no tuples, and pages > > > with headers and only a few tuples. If any of those are insecure, > > > they > > > all are. Therefore, I don't see any reason to treat them differently. > > > > > > > > > We had to special case zero pages and not encrypt them because as far as > > > I can > > > tell, there is no atomic way to extend a file and initialize it to > > > Enc(zero) in > > > the same step. > > > > Oh, good point. Yeah, we will need to handle that. > > Not sure what's meant here by 'handle that', but I don't see any > particular reason to avoid doing exactly the same for zero pages with > TDE in core..? I don't think there's any reason we need to make things > complicated to ensure that we encrypt entirely empty pages.
I thought he was saying that when you extend a file, you might have to extend it with all zeros, rather than being able to extend it with an actual encrypted page of zeros. For example, I think when a page is corrupt in storage, it reads back as a fully zero page, and we would need to handle that. Are you saying we already have logic to handle that so we don't need to change anything? -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com If only the physical world exists, free will is an illusion.
