Re: [TLS] DTLS 1.3 AEAD additional data

[Christopher Wood <[e-mail]>]

On Thu, Apr 23, 2020, at 2:17 PM, Eric Rescorla wrote:
> On Thu, Apr 23, 2020 at 12:40 AM Martin Thomson <[e-mail]> wrote:
> > On Thu, Apr 23, 2020, at 11:49, Eric Rescorla wrote:
> >  > OK but we would expect the peer to process CID-less records if they are 
> >  > coalesced?
> > 
> >  I guess so. If we allowed them to drop them, then we're close to saying MUST NOT omit.
> 
> Yeah, I would make three points
> 
> 1. Allowing implicit CIDs is very recent (it was introduced in -34) 
> 2. The CID specification explicitly prohibits it for DTLS 1.2.
> 3. I haven't really heard a very compelling argument for this and I 
> note that QUIC forbids it [and in fact has much worse problems when you 
> mix epochs because the long header is so long]
> 
> So, given that the simplest and most consistent thing is to simply 
> forbid it: can someone make an argument for why this is important to 
> permit?

Thanks to everyone who participated in this thread so far! Given the points above, the chairs would like to hear arguments in favor of implicit CIDs. Absent substantial rationale, we'll assume rough consensus for explicit CIDs. 

Best,
Chris, on behalf of the chairs