| From: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Joe Conway <mail(at)joeconway(dot)com>, Antonin Houska <ah(at)cybertec(dot)at>, Stephen Frost <sfrost(at)snowman(dot)net>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, "Moon, Insung" <Moon_Insung_i3(at)lab(dot)ntt(dot)co(dot)jp>, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [Proposal] Table-level Transparent Data Encryption (TDE) and Key Management Service (KMS) |
| Date: | 2019-07-31 07:58:49 |
| Message-ID: | CAD21AoDtd7LwuYTdgogrEBCan2x7z9soJ-RA2YB-eu3uLsqPCQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Jul 31, 2019 at 3:29 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
>
> For WAL encryption, before flushing WAL we encrypt whole 8k WAL page
> and then write only the encrypted data of the new WAL record using
> pg_pwrite() rather than write whole encrypted page. So each time we
> encrypt 8k WAL page we end up with encrypting different data with the
> same key+nonce but since we don't write to the disk other than space
> where we actually wrote WAL records it's not a problem. Is that right?
Hmm that's incorrect. We always write an entire 8k WAL page even if we
write a few WAl records into a page. It's bad because we encrypt
different pages with the same key+IV, but we cannot change IV for each
WAL writes as we end up with changing also
already-flushed-WAL-records. So we might need to change the WAL write
so that it write only WAL records we actually wrote.
Regards,
--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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