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

On Tue, Jul 09, 2019 at 05:31:49PM -0400, Alvaro Herrera wrote:
>On 2019-Jul-09, Tomas Vondra wrote:
>
>> On Tue, Jul 09, 2019 at 05:06:45PM -0400, Alvaro Herrera wrote:
>> > On 2019-Jul-09, Joe Conway wrote:
>> >
>> > > > Ot you could just encrypt them with a different key, and you would not
>> > > > need to make database OID part of the nonce.
>> > >
>> > > Yeah that was pretty much exactly what I was trying to say above ;-)
>> >
>> > So you need to decrypt each file and encrypt again when doing CREATE
>> > DATABASE?
>>
>> The question is whether we actually need to do that?
>
>I mean if the new database is supposed to be encrypted with key B, you
>can't just copy the files from the other database, since they are
>encrypted with key A, right?  Even if you consider that both copies of
>each table have the same OID and each block has the same nonce.
>

Sure, if the databases are supposed to be encrypted with different keys,
then we may need to re-encrypt the files. I don't see a way around that,
but maybe we could use the scheme with master key somehow.

>> Do we change OIDs of relations when creating the database? If not, we
>> don't need to re-encrypt because having copies of the same block
>> encrypted with the same nonce is not an issue (just like copying
>> encrypted files is not an issue).
>
>Are you thinking that the files can be decrypted by the two keys
>somehow?
>

No, I was kinda assuming the database will start with the same key, but
that might have been a silly idea.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
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