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

Stephen Farrell <stephen.farrell@cs.tcd.ie> Fri, 07 July 2017 21:41 UTC

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To: Russ Housley <housley@vigilsec.com>
Cc: IETF TLS <tls@ietf.org>, Matthew Green <matthewdgreen@gmail.com>
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From: 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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On 07/07/17 22:38, Russ Housley wrote:
> 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.  If one
> of the parties is "compelled" to install the centrally managed (EC)DH
> key, then the server is aware. 

CDNs.

Cheers,
S.

? If you consider the server to be the
> sending party, then this situation does not meet number 1 in the
> definition.  If you consider the server to be the receiving party,
> then this situation does not meet number 2 in the definition.
> 
> To save everyone from looking it up, RFC 2804 says:
> 
> Wiretapping is what occurs when information passed across the 
> Internet from one party to one or more other parties is delivered to 
> a third party:
> 
> 1. Without the sending party knowing about the third party
> 
> 2. Without any of the recipient parties knowing about the delivery
> to the third party
> 
> 3. When the normal expectation of the sender is that the transmitted 
> information will only be seen by the recipient parties or parties 
> obliged to keep the information in confidence
> 
> 4. When the third party acts deliberately to target the transmission 
> of the first party, either because he is of interest, or because the
> second party's reception is of interest.
> 
> The term "party", as used here, can refer to one person, a group of 
> persons, or equipment acting on behalf of persons; the term "party" 
> is used for brevity.
> 
> Of course, many wiretaps will be bidirectional, monitoring traffic 
> sent by two or more parties to each other.
> 
> Thus, for instance, monitoring public newsgroups is not wiretapping 
> (condition 3 violated), random monitoring of a large population is 
> not wiretapping (condition 4 violated), a recipient passing on 
> private email is not wiretapping (condition 2 violated).
> 
> Russ
>