Re: Transparent Data Encryption (TDE) and encrypted files

On Tue, Oct 1, 2019 at 9:33 AM Tels <nospam-pg-abuse(at)bloodgate(dot)com> wrote:

> Moin,
>
> On 2019-09-30 23:26, Bruce Momjian wrote:
> > For full-cluster Transparent Data Encryption (TDE), the current plan is
> > to encrypt all heap and index files, WAL, and all pgsql_tmp (work_mem
> > overflow). The plan is:
> >
> >
> https://wiki.postgresql.org/wiki/Transparent_Data_Encryption#TODO_for_Full-Cluster_Encryption
> >
> > We don't see much value to encrypting vm, fsm, pg_xact, pg_multixact,
> > or
> > other files. Is that correct? Do any other PGDATA files contain user
> > data?
>
> IMHO the general rule in crypto is: encrypt everything, or don't bother.
>
> If you don't encrypt some things, somebody is going to find loopholes
> and sidechannels
> and partial-plaintext attacks. Just a silly example: If you trick the DB
> into putting only one row per page,
> any "bit-per-page" map suddenly reveals information about a single
> encrypted row that it shouldn't reveal.
>
> Many people with a lot of free time on their hands will sit around,
> drink a nice cup of tea and come up
> with all sorts of attacks on these things that you didn't (and couldn't)
> anticipate now.
>
> So IMHO it would be much better to err on the side of caution and
> encrypt everything possible.
>

+1.

Unless we are *absolutely* certain, I bet someone will be able to find a
side-channel that somehow leaks some data or data-about-data, if we don't
encrypt everything. If nothing else, you can get use patterns out of it,
and you can make a lot from that. (E.g. by whether transactions are using
multixacts or not you can potentially determine which transaction they are,
if you know what type of transactions are being issued by the application.
In the simplest case, there might be a single pattern where multixacts end
up actually being used, and in that case being able to see the multixact
data tells you a lot about the system).

As for other things -- by default, we store the log files in text format in
the data directory. That contains *loads* of sensitive data in a lot of
cases. Will those also be encrypted?

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>