Horton

Re: Internal key management system

Bruce Momjian <bruce@momjian.us>

View thread
From: Bruce Momjian <bruce@momjian.us>
To: Masahiko Sawada <masahiko.sawada@2ndquadrant.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, "Moon, Insung" <tsukiwamoon.pgsql@gmail.com>, Cary Huang <cary.huang@highgo.ca>, Robert Haas <robertmhaas@gmail.com>, Fabien COELHO <coelho@cri.ensmp.fr>, Sehrope Sarkuni <sehrope@jackdb.com>, cary huang <hcary328@gmail.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Joe Conway <mail@joeconway.com>
Date: 2020-03-19T15:35:34Z
Lists: pgsql-hackers 
On Thu, Mar 19, 2020 at 11:42:36PM +0900, Masahiko Sawada wrote:
> On Thu, 19 Mar 2020 at 22:00, Bruce Momjian <bruce@momjian.us> wrote:
> >
> > On Thu, Mar 19, 2020 at 06:32:57PM +0900, Masahiko Sawada wrote:
> > > On Thu, 19 Mar 2020 at 15:59, Masahiko Sawada
> > > > I understand that your idea is to include fixed length string to the
> > > > 256 bit key in order to separate key space. But if we do that, I think
> > > > that the key strength would actually be the same as the strength of
> > > > weaker key length, depending on how we have the fixed string. I think
> > > > if we want to have multiple key spaces, we need to derive keys from the
> > > > master key using KDF.
> > >
> > > Or we can simply generate a different encryption key for block
> > > encryption. Therefore we will end up with having two encryption keys
> > > inside database. Maybe we can discuss this after the key manager has
> > > been introduced.
> >
> > I know Sehrope liked derived keys so let's get his feedback on this.  We
> > might want to have two keys anyway for key rotation purposes.
> >
> 
> Agreed. Maybe we can derive a key for the use of wrap and unwrap SQL
> interface by like HKDF(MK, 'USER_KEY:') or HKDF(KM, 'USER_KEY:' ||
> system_identifier).

Well, the issue is if the user can control the user key, there might be
a way to make the user key do nothing.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +