On Tue, Jun 13, 2017 at 10:28:14AM -0400, Peter Eisentraut wrote:
> On 6/13/17 09:24, Stephen Frost wrote:
> > but there are use-cases where it'd be really nice to be able to
> > have PG doing the encryption instead of the filesystem because
> > then you can do things like backup the database, copy it somewhere
> > else directly, and then restore it using the regular PG
> > mechanisms, as long as you have access to the key. That's not
> > something you can directly do with filesystem-level encryption
>
> Interesting point.
>
> I wonder what the proper extent of "encryption at rest" should be.
> If you encrypt just on a file or block level, then someone looking
> at the data directory or a backup can still learn a number of things
> about the number of tables, transaction rates, various configuration
> settings, and so on.
In the end, information leaks at a strictly positive baud rate because
physics (cf. Claude Shannon, et al).
Encryption at rest is one technique whereby people can slow this rate,
but there's no such thing as getting it to zero. Let's not creep this
feature in the ultimately futile attempt to do so.
> In the scenario of a sensitive application hosted on a shared
> SAN, I don't think that is good enough.
>
> Also, in the use case you describe, if you use pg_basebackup to make a
> direct encrypted copy of a data directory, I think that would mean you'd
> have to keep using the same key for all copies.
Right.
Best,
David.
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