Re: [MMUSIC] Stephen Farrell's No Objection on draft-ietf-mmusic-sdp-mux-attributes-14: (with COMMENT)
Stephen Farrell <stephen.farrell@cs.tcd.ie> Sun, 30 October 2016 21:51 UTC
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To: Suhas Nandakumar <suhasietf@gmail.com>
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From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Date: Sun, 30 Oct 2016 21:50:57 +0000
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Cc: mmusic-chairs@ietf.org, draft-ietf-mmusic-sdp-mux-attributes@ietf.org, The IESG <iesg@ietf.org>, mmusic WG <mmusic@ietf.org>
Subject: Re: [MMUSIC] Stephen Farrell's No Objection on draft-ietf-mmusic-sdp-mux-attributes-14: (with COMMENT)
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Hiya, On 26/10/16 23:47, Suhas Nandakumar wrote: > Hello Stephen > > Thanks for the review . please see inline. > > On Wed, Oct 26, 2016 at 2:50 AM, Stephen Farrell <stephen.farrell@cs.tcd.ie> > wrote: > >> Stephen Farrell has entered the following ballot position for >> draft-ietf-mmusic-sdp-mux-attributes-14: No Objection >> >> When responding, please keep the subject line intact and reply to all >> email addresses included in the To and CC lines. (Feel free to cut this >> introductory paragraph, however.) >> >> >> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html >> for more information about IESG DISCUSS and COMMENT positions. >> >> >> The document, along with other ballot positions, can be found here: >> https://datatracker.ietf.org/doc/draft-ietf-mmusic-sdp-mux-attributes/ >> >> >> >> ---------------------------------------------------------------------- >> COMMENT: >> ---------------------------------------------------------------------- >> >> >> - 4.5 and 5.7: What if the different a=crypto lines >> specify different strength ciphersuites? Wouldn't it be >> better to pick the strongest or to say they MUST be the >> same (as is done in 5.35)? If picking the first is the >> right answer then maybe warn folks to not put a stronger >> ciphersuite anywhere else? >> > > > [Suhas]: I did think about it some more and I am not sure the mux draft > opens up an vulnerability in this scenario. > For example, Even with the IDENTICAL category, the Offerer can include a > weak cipher in all the m=lines and thus force the Answerer to select the > weak one or have the Answerer reject the Offer. I am not sure if making it > iDENTICAL would help us guard against the wrong cipher selection. > . > In the TRANSPORT scenario, if the Answerer selected the m=line with a weak > cipher the Offerer has 2 options a) Don't include the weak cipher b) Do > another Offer/Answer with the modified list (with strong ciphers or > inactive media) > > Please advise .. It's less an issue of creating a vulnerability as it is of making it easier for people to end up in a situation where they think they have better security than is in fact the case. I think experience shows that disallowing differences of that kind is a good plan. But I could understand if it was the case that allowing such discrepancies made it easier to get interop in some cases. I don't know if that latter is the case. > > > > >> >> - 5.36 vs. 5.39: It wasn't clear to me why these have >> different rules - can you explain? >> >> >> > [Suhas] : It looks like both the fingerprint (Section 5.36) and > zrtp-hash(5.39) attributes have the same Multiplexing category of TRANSPORT > assigned and thus follow the same rules. Am i missing something here ? > In the ZRTP case you have a MUST and level == M. In the other there's no MUST and it has level == B. At this point I forget what those level things mean though;-) S. > >> _______________________________________________ >> mmusic mailing list >> mmusic@ietf.org >> https://www.ietf.org/mailman/listinfo/mmusic >> >
- [MMUSIC] Stephen Farrell's No Objection on draft-… Stephen Farrell
- Re: [MMUSIC] Stephen Farrell's No Objection on dr… Suhas Nandakumar
- Re: [MMUSIC] Stephen Farrell's No Objection on dr… Stephen Farrell
- Re: [MMUSIC] Stephen Farrell's No Objection on dr… Cullen Jennings (fluffy)
- Re: [MMUSIC] Stephen Farrell's No Objection on dr… Stephen Farrell