Re: Internal key management system

On Tue, 24 Mar 2020 at 23:15, Bruce Momjian <bruce@momjian.us> wrote:
>
> On Tue, Mar 24, 2020 at 02:29:57PM +0900, Masahiko Sawada wrote:
> > That seems to work fine.
> >
> > So we will have pg_cryptokeys within PGDATA and each key is stored
> > into separate file named the key id such as "sql", "tde-wal" and
> > "tde-block". I'll update the patch and post.
>
> Yes, that makes sense to me.
>

I've attached the updated patch. With the patch, we have three
internal keys: SQL key, TDE-block key and TDE-wal key. Only SQL key
can be used so far to wrap and unwrap user secret via pg_wrap and
pg_unwrap SQL functions. Each keys is saved to the single file located
at pg_cryptokeys. After initdb with enabling key manager, the
pg_cryptokeys directory has the following files:

$ ll data/pg_cryptokeys
total 12K
-rw------- 1 masahiko staff 132 Mar 25 15:45 0000
-rw------- 1 masahiko staff 132 Mar 25 15:45 0001
-rw------- 1 masahiko staff 132 Mar 25 15:45 0002

I used the integer id rather than string id to make the code simple.

When cluster passphrase rotation, we update all keys atomically using
temporary directory as follows:

1. Derive the new passphrase
2. Wrap all internal keys with the new passphrase
3. Save all internal keys to the temp directory
4. Remove the original directory, pg_cryptokeys
5. Rename the temp directory to pg_cryptokeys

In case of failure during rotation, pg_cyrptokeys and
pg_cyrptokeys_tmp can be left in an incomplete state. We recover it by
checking if the temporary directory exists and the wrapped keys in the
temporary directory are valid.

Regards,

-- 
Masahiko Sawada            http://www.2ndQuadrant.com/
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