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Re: [TLS] Comments on draft-ietf-tls-exported-authenticator-00

Benjamin Kaduk <bkaduk@akamai.com> Tue, 23 May 2017 20:12 UTC

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To: Nick Sullivan <nicholas.sullivan@gmail.com>, tls@ietf.org
References: <CAN2QdAHByU1kxgit9J2KqOp1ujz4xWG8QEgAsZQCZWjfoZ2S=A@mail.gmail.com> <CAOjisRziY8KhF163V=VhQGGyXJVkgsQ9QGsqVSpzJMbkvXYO4w@mail.gmail.com>
From: Benjamin Kaduk <bkaduk@akamai.com>
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Date: Tue, 23 May 2017 15:11:56 -0500
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Subject: Re: [TLS] Comments on draft-ietf-tls-exported-authenticator-00
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On 05/23/2017 03:07 PM, Nick Sullivan wrote:
> 3) In TLS 1.3 post-handshake authentication, each successive
> certificate added to the connection is incorporated into the handshake
> state. The last certificate in a sequence of authentications would
> result in a connection in which the party could say they were jointly
> authoritative a over multiple identities. In exported authenticators,
> the only state that is signed comes from the original handshake, so
> there's no way to order them. Each exported authenticator is tied to
> the connection, but not tied directly to another authenticator, and
> therefore there is no proof that the party is "jointly authoritative".
> I welcome text changes to make this more clear.

I thought at least for "normal" post-handshake auth, the handshake hash
used was always just the initial handshake, and did not include
intermediate certificates that had been transmitted.

-Ben

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