[TLS] Fwd: Stephen Farrell's Discuss on draft-ietf-tsvwg-sctp-dtls-encaps-08: (with DISCUSS and COMMENT)

Stephen Farrell <stephen.farrell@cs.tcd.ie> Mon, 19 January 2015 20:56 UTC

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Date: Mon, 19 Jan 2015 20:56:40 +0000
From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Subject: [TLS] Fwd: Stephen Farrell's Discuss on draft-ietf-tsvwg-sctp-dtls-encaps-08: (with DISCUSS and COMMENT)
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Please see my DISCUSS on a document below - the interesting
question relates to which version of DTLS to mandate for
WebRTC in general, as I think once this document is done,
others will just copy the relevant text.

I don't think there are any major security issues involved,
but that this is more to do with implementations. But I'd
welcome any opinions or information about any important
security differences or about whether or not current
implementations mean DTLS1.2 should be ok to mandate here
today or not.

I've set reply-to as my address and not the TLS list as
I don't think the TLS WG need to debate this much and I'm
really just checking, so please don't bother the WG list
unless there's a real point of interest for the WG. And
to repeat: I'm just checking more thoroughly than usual
on this one since this will I think set a precedent for

Feedback is also needed by this Thursday 22nd to be useful.
Sorry about that but thanks in advance if you do manage to
send some:-)


-------- Forwarded Message --------
Subject: Stephen Farrell's Discuss on
draft-ietf-tsvwg-sctp-dtls-encaps-08: (with DISCUSS and COMMENT)
Date: Mon, 19 Jan 2015 12:48:11 -0800
From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
To: The IESG <iesg@ietf.org>
CC: Gorry Fairhurst <gorry@erg.abdn.ac.uk>

Stephen Farrell has entered the following ballot position for
draft-ietf-tsvwg-sctp-dtls-encaps-08: Discuss

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The document, along with other ballot positions, can be found here:


I'll clear once we've checked on this. Section 5 says
DTLS1.0 (from 2006) is MTI and DTLS1.2 (2012) is a
SHOULD. I could imagine that being reasonable when
DTLS1.2 was newish, say when this work was getting
started 2 years ago, but now a couple of years have
passed, it might well be just fine to require DTLS1.2 -
a lot has happened since and TLS1.2 deployment is now
far ahead of where it was in 2012, and most specs have
tended to include text like this because some
implementers only had the older TLS version. So the
DISCUSS is - is the 9 year old RFC still needed as MTI
- can we not just say to use 1.2 now?  (Note: since
this is sort-of a WebRTC spec, I think it's worth
quickly re-visiting this question now to be sure we're
taking the right approach, as the answer we pick here
is quite likely to be followed by other WebRTC docs
over the next year or so. I think this is the first
relevant WebRTC protocol spec with this bit of text
isn't it?  Apologies to the authors of this one for
landing the discuss on them:-)


- Figure 1: Couldn't ICE/UDP be somewhat confusing for
someone unaware that ICE is more of an algorithm than a
wire protocol? Might be nice to clarify that here in
the intro. (If you want to be nice, if you don't that's
ok too and can be the right decision.)

- section 3: Isn't "complete SCTP packet" a teeny bit
ambiguous? It could mean including the IP and other
lower headers but I guess you do not. But that's a nit
since it's probably clear enough that you don't put an
IP or layer 2 header into the DTLS payload:-)

- Given heartbleed, and the use here of RFC6520 I think
some note of that famous implementation bug would be
wise. Just to a pointer to how to not have that
problem. But it's not a protocol bug so I'm not trying
to insist, i.e. no need for us to argue the toss on

- I'm also wondering if the text here on 6520 is
sufficiently clear given this week's discussion of that
on the rtcweb list. (I'm not on tsvwg@ so would
appreciate an update on how the thread [1] pans out on
the tsvwg list before we approve this.)

  [1] https://www.ietf.org/mail-archive/web/rtcweb/current/msg14069.html