Re: DSM segment handle generation in background workers

On Wed, Nov 14, 2018 at 6:34 PM Noah Misch <noah@leadboat.com> wrote:
> On Wed, Nov 14, 2018 at 05:50:26PM +1300, Thomas Munro wrote:
> > On Wed, Nov 14, 2018 at 3:24 PM Noah Misch <noah@leadboat.com> wrote:
> > > What counts is the ease of predicting a complete seed.  HEAD's algorithm has
> > > ~13 trivially-predictable bits, and the algorithm that stood in BackendRun()
> > > from 98c5065 until 197e4af had no such bits.  You're right that the other 19
> > > bits are harder to predict than any given 19 bits under the old algorithm, but
> > > the complete seed remains more predictable than it was before 197e4af.
> >
> > However we mix them, given that the source code is well known, isn't
> > an attacker's job really to predict the time and pid, two not
> > especially well guarded secrets?
>
> True.  Better to frame the issue as uniform distribution of seed, not
> unpredictability of seed selection.

What do you think about the attached?

-- 
Thomas Munro
http://www.enterprisedb.com