Re: [TLS] Call for adoption of draft-sullivan-tls-exported-authenticator

I've read the draft, and I support its adoption.  I believe that the
mechanism
is sound for its stated use.

I have some minor concerns about the wording in the draft, though.  First,
the
draft describes the authenticators as sent "out-of-band", while my
understanding is that they are always intended to be sent in-band as
application data.  If they were truly sent out-of-band, there would be some
questions about the security analysis, because that would imply those could
be
sent unprotected.  Hence, I suggest the draft to adapt the premise that
exported authenticators MUST be sent as application data within the same
connection.  This might simplify your security proofs too.

The second issue I have is with the question of when does authentication
succeed.  In TLS, by the time any party can send application data, normally
(with exception of server-to-client data in client auth case) both parties
know
that the other side has authenticated them.  Here, a new identity is
introduced
while application data can be already in flight, and it's not clear to me
when
the sender of the exported authenticator can act assuming the peer has
accepted
its new identity.  My current understanding is that this issue is deferred
to
the application layer, but it would be nice to discuss those considerations
explicitly.

The last question I have is how does this interact with the state of TLS
connection.  Does accepting a new identity mean that the entire connection
now
has that identity too?  Does this mean that the session tickets issued after
the library receives the authenticator are valid for the new identity?
Does it
make the tickets sent previously on that connection valid for the new
identity?

Also, what is the distinction between "jointly authoritative for A and B"
and
"individually authoritative for A and individually authoritative for B"?

  -- Victor.

On Fri, Apr 14, 2017 at 12:29 AM, Joseph Salowey <joe@salowey.net> wrote:

> Hey Folks,
>
> At the IETF 98 meeting in Chicago there was support in the room to adopt
> draft-sullivan-tls-exported-authenticator [0]. We are looking for
> feedback on adopting this draft form the list. Please respond if you
> support the draft and are willing to review it. If you object to its
> adoption, please let us know why. Please respond to the list by 20170501
>
> Cheers,
>
> J&S
>
> [0] https://datatracker.ietf.org/doc/html/draft-sullivan-tls
> -exported-authenticator
>
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>