Re: [TLS] draft-green-tls-static-dh-in-tls13-01

Russ Housley <housley@vigilsec.com> Fri, 07 July 2017 21:54 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Fri, 7 Jul 2017 17:54:02 -0400
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To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Subject: Re: [TLS] draft-green-tls-static-dh-in-tls13-01
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Stephen:


>>>>> You didn't refer to 2804 and the standards track. As an author
>>>>> do you really think this can be on the standards track and yet
>>>>> not obsolete 2804?
>>>> 
>>>> Yes.
>>> 
>>> We disagree.
>>> 
>>>> Section 3 of RFC 2804 offers pretty clear definition of 
>>>> wiretapping, and that is not what is going on here.  In this 
>>>> situation, all of the parties are part of the same organization, 
>>>> under common key management.
>>> 
>>> That is one possible deployment. There is nothing in this proposal
>>> that limits it's use to that.
>>> 
>>>> The server must explicitly accept and use the centrally managed
>>>> (EC)DH key, so that party is completely aware and, in fact,
>>>> enabling the other parties to decrypt the traffic.
>>> 
>>> Yes, and the server could equally be compelled to do that, in which
>>> case this technology would clearly be a standard form of
>>> wiretapping.
>>> 
>>> Claiming that is not the case would be incredible so I have no idea
>>> how you maintain that this isn't in conflict with 2804.
>> 
>> That does not follow the definition in Section 3 of RFC 2804.  
> 
> And also: I'm sorry to have to say it, but I consider that
> attempted weasel wording around the clear intent of 2804. The
> clear and real effect if your wiretapping proposal were standardised
> by the IETF would be that we'd be standardising ways in which
> TLS servers can be compelled into breaking TLS - it'd be a standard
> wiretapping API that'd be insisted upon in many places and would
> mean significantly degrading TLS (only *the* most important
> security protocol we maintain) and the community's perception
> of the IETF. It's all a shockingly bad idea.

I clearly disagree.  Otherwise, I would not have put any work into the draft.

Russ