Re: [TLS] DTLS 1.3 ACKs

[Ilari Liusvaara <[e-mail]>]

On Wed, Oct 25, 2017 at 08:48:56AM +0200, Nikos Mavrogiannopoulos wrote:
> On Mon, 2017-10-23 at 18:14 -0700, Eric Rescorla wrote:
> > We now have DTLS 1.3 implemented in NSS, which went pretty cleanly.
> > 
> > The one thing we ran into was the potential need to ACK in cases
> > where you
> > can't process *any* records (e.g., you receive what's actually EE,
> > but you
> > can't decrypt it). In this case, you want to send an empty ACK.
> > 
> > See PR:
> > https://github.com/tlswg/dtls13-spec/pull/14
> 
> Would it make sense to spell out the goals (and maybe some motivation)
> for the DTLS 1.3 revision in the draft? The TLS WG charter contains the
> goals for the TLS 1.3 revision but changes in DTLS like the ACK
> although nice, seem to be unrelated to them.

The ACK message has two goals:

The more important one: To acknowledge some flights that do not have
reply messages. NewSessionTicket is especially relevant case. Also
client authentication flights.

The less important one: To reduce amount that needs to be retransmitted
on packet loss.



-Ilari