Re: [Cfrg] Closing out tls1.3 "Limits on key usage" PRs (#765/#769)

Russ Housley <housley@vigilsec.com> Fri, 10 March 2017 15:42 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Fri, 10 Mar 2017 10:42:08 -0500
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Subject: Re: [Cfrg] Closing out tls1.3 "Limits on key usage" PRs (#765/#769)
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Thanks.  I agree.  I think that the existing text is more helpful to the implementer.  If the details of the analysis do in the document, it should be in the security considerations.

Russ


> On Mar 9, 2017, at 9:18 PM, Sean Turner <sean@sn3rd.com> wrote:
> 
> After many emails about the wording for s5.5 Limits on Key Usage, it’s time to judge consensus on whether or not to make any changes to that section.  The important thing is that the SHOULD implement the key update from s4.5.3 was never in question.  There was no consensus to change the actual GCM limits on key usage; again the text related to ChaCha20/Poly1305 never really was in question.  The discussion has wound down to whether it was better to count records or bytes/blocks for the GCM limit calculation.  We didn’t see any strong consensus to change this description.  Therefore, we see no consensus to change the text in s5.5.  ekr please close PR#765 and PR#769.
> 
> J&S
> 
>> On Feb 10, 2017, at 12:07 AM, Sean Turner <sean@sn3rd.com> wrote:
>> 
>> All,
>> 
>> We’ve got two outstanding PRs that propose changes to draft-ietf-tls-tls13 Section 5.5 “Limits on Key Usage”.  As it relates to rekeying, these limits have been discussed a couple of times and we need to resolve once and for all whether the TLS WG wants to:
>> 
>> a) Close these two PRs and go with the existing text [0]
>> b) Adopt PR#765 [1]
>> c) Adopt PR#769 [2]
>> 
>> Please indicate you preference to the TLS mailing list before Feb 17.  Note that unless there’s clear consensus to change the text will remain as is (i.e., option a).
>> 
>> J&S
>> 
>> [0] https://tlswg.github.io/tls13-spec/#rfc.section.5.5
>> [1] https://github.com/tlswg/tls13-spec/pull/765
>> [2] https://github.com/tlswg/tls13-spec/pull/769