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

Greetings,

* Bruce Momjian (bruce@momjian.us) wrote:
> On Wed, Jul 10, 2019 at 12:38:02PM -0600, Ryan Lambert wrote:
> >
> >     what is it that gets stored in the page for
> >     decryption use, the nonce or the IV derived from it?
> >
> >
> > I believe storing the IV is preferable and still secure per [1]: "The IV need
> > not be secret"
> >
> > Beyond needing the database oid, if every decrypt function has to regenerate
> > the IV from the nonce that will affect performance.  I don't know how expensive
> > the forward hash is but it won't be free.
>
> Well, I think we have three options.  We have 3 4-byte integers
> (pg_class.oid, LSN, page-number) that could be concatenated to be the
> IV, we could run those through a hash, or we could run them through the
> encryption function with the secret.

I didn't see where it was said that using a hash was a good idea in this
context..?  Encrypting it with the key looked like it was discussed as a
viable option.  I had understood that part of the point of using the
table OID and page-number was also so that we didn't have to explicitly
store the result, therefore requiring us to need less space on the page
to make this happen.

Thanks,

Stephen