Re: [Proposal] Table-level Transparent Data Encryption (TDE) and KeyManagement Service (KMS)

Greetings,

* Tomas Vondra (tomas.vondra@2ndquadrant.com) wrote:
> On Sun, Jun 16, 2019 at 02:10:23PM -0400, Stephen Frost wrote:
> >* Joe Conway (mail@joeconway.com) wrote:
> >>On 6/16/19 9:45 AM, Bruce Momjian wrote:
> >>> On Sun, Jun 16, 2019 at 07:07:20AM -0400, Joe Conway wrote:
> >>>> In any case it doesn't address my first point, which is limiting the
> >>>> volume encrypted with the same key. Another valid reason is you might
> >>>> have data at varying sensitivity levels and prefer different keys be
> >>>> used for each level.
> >>>
> >>> That seems quite complex.
> >>
> >>How? It is no more complex than encrypting at the tablespace level
> >>already gives you - in that case you get this property for free if you
> >>care to use it.
> >
> >Perhaps not surprising, but I'm definitely in agreement with Joe
> >regarding having multiple keys when possible and (reasonably)
> >straight-forward to do so.  I also don't buy off on the OpenSSL
> >argument; their more severe issues certainly haven't been due to key
> >management issues such as what we're discussing here, so I don't think
> >the argument applies.
>
> I'm not sure what exactly is the "OpenSSL argument" you're disagreeing
> with? IMHO Bruce is quite right that the risk of vulnerabilities grows
> with the complexity of the system (both due to implementation bugs and
> general design weaknesses). I don't think it's tied to the key
> management specifically, except that it's one of the parts that may
> contribute to the complexity.

While I understand that complexity of the system can lead to
vulnerabilities, I don't agree that it's appropriate or sensible to
equate the ones that OpenSSL has had to deal with as being similar to
what we might have to deal with, given this additional proposed
complexity.

> (It's often claimed that key management is one of the weakest points of
> current crypto systems - we have safe (a)symmetric algorithms, but safe
> handling of keys is an issue. I don't have data / papers supporting this
> claim, I kinda believe it.)

Yes, I agree entirely that key management is absolutely one of the
hardest things to get right in crypto systems.  It is, however, not what
the OpenSSL issues have been about and so while I agree that we may have
some bugs there, it's not fair to say that they're equivilant to what
OpenSSL has been dealing with.

> Now, I'm not opposed to eventually implementing something more
> elaborate, but I also think just encrypting the whole cluster (not
> necessarily with a single key, but with one master key) would be enough
> for vast majority of users. Plus it's less error prone and easier to
> operate (backups, replicas, crash recovery, ...).

I agree that it'd be better than nothing but if we have the opportunity
now to introduce what would hopefully be a relatively small capability,
then I'm certainly all for it.

> But there's about 0% chance we'll get that in v1, of course, so we need
> s "minimum viable product" to build on anyway.

There seems like a whole lot of space between something very elaborate
and only supporting one key.

Thanks,

Stephen