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

On 7/10/19 2:38 AM, Masahiko Sawada wrote:
> On Tue, Jul 9, 2019 at 9:01 PM Joe Conway <mail(at)joeconway(dot)com> wrote:
>>
>> On 7/9/19 6:07 AM, Peter Eisentraut wrote:
>> > On 2019-07-08 18:09, Joe Conway wrote:
>> >> In my mind, and in practice to a
>> >> large extent, a postgres tablespace == a unique mount point.
>> >
>> > But a critical difference is that in file systems, a separate mount
>> > point has its own journal.
>>
>> While it would be ideal to have separate WAL, and even separate shared
>> buffer pools, per tablespace, I think that is too much complexity for
>> the first implementation and we could have a single separate key for all
>> WAL for now.
>
> If we encrypt different tables with different keys I think we need to
> encrypt WAL with the same keys as we used for tables, as per
> discussion so far. And we would need to encrypt each WAL records, not
> whole WAL 8k pages.

That is not a technical requirement to be sure. We may decide we want
that from a security perspective, but that point is debatable. There
have been different goals expressed on this thread:

1. Keep user 1 from decrypting data A and user 2 from decrypting data B
2. Limit the amount of data encrypted with key Kn

We can use K1 for A, K2 for B, and K3 for WAL and achieve goal #2. As
Stephen pointed out, goal #1 would be great to have, but I am not sure
there is consensus that it is required, at least not for the initial
implementation.

Joe
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