Re: [TLS] WGLC for draft-ietf-tls-exported-authenticator

Roelof duToit <r@nerd.ninja> Wed, 09 May 2018 13:21 UTC

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From: Roelof duToit <r@nerd.ninja>
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Date: Wed, 9 May 2018 09:20:43 -0400
Cc: "<tls@ietf.org>" <tls@ietf.org>, Eric Rescorla <ekr@rtfm.com>
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] WGLC for draft-ietf-tls-exported-authenticator
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Perhaps, but it still behooves us to warn implementors that a significant percentage of enterprise traffic will break with this mechanism.

> On May 9, 2018, at 3:39 AM, Martin Thomson <martin.thomson@gmail.com> wrote:
> 
> This isn't really a security consideration though, it's a truism.  A MitM
> can break things that depend on end-to-end integrity of the connection.
> On Wed, May 9, 2018 at 11:25 AM Roelof duToit <r@nerd.ninja> wrote:
> 
>> If the use of the mechanism is not negotiated on the TLS level then I
> would appreciate it if the “Security Considerations” section of the draft
> could be amended to include a paragraph that warns potential implementors
> that protocol-agnostic middleboxes will break the mechanism without any
> clear failure indicators.
> 
>>> On May 8, 2018, at 8:13 PM, Martin Thomson <martin.thomson@gmail.com>
> wrote:
>>> 
>>> On Wed, May 9, 2018 at 2:20 AM Roelof duToit <r@nerd.ninja> wrote:
>>> 
>>>> I understand that there is not really anything to negotiate per se, but
>>> would it not be prudent to add a TLS extension to negotiate support for
>>> exported-authenticator in the TLS layer prior to using it in the
>>> application layer?
>>> 
>>> We don't signal the potential need for exporters.  I see no reason to
>>> signal this either.  Any signaling necessary really belongs at the
> higher
>>> layer.