From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Ants Aasma <ants(at)cybertec(dot)at>, Sasasu <i(at)sasa(dot)su>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: storing an explicit nonce |
Date: | 2021-10-07 15:45:35 |
Message-ID: | 20211007154535.GB5475@momjian.us |
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Lists: | pgsql-hackers |
On Thu, Oct 7, 2021 at 10:28:55AM -0400, Robert Haas wrote:
> However, there's also the option of storing a nonce in each page, as
> suggested by the subject of this thread. I think that's probably a
> pretty workable approach, as demonstrated by the patch that started
> this thread. We'd need to think a bit carefully about whether any of
> the compile-time calculations the patch moves to runtime are expensive
> enough to matter and whether any such impacts can be mitigated, but I
> think there is a good chance that such issues are manageable.
>
> I'm a little concerned by the email from "Sasasu" saying that even in
> XTS reusing the IV is not cryptographically weak. I don't know enough
> about these different encryption modes to know if he's right, but if
> he is then perhaps we need to consider his suggestion of using
> AES-GCM. Or, uh, something else.
I continue to be concerned that a page format change will decrease the
desirability of this feature by making migration complex and increasing
its code complexity. I am unclear if it is necessary.
I think the big question is whether XTS with db/relfilenode/blocknumber
is sufficient as an IV without a nonce that changes for updates.
--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com
If only the physical world exists, free will is an illusion.
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