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Re: [TLS] draft-ietf-tls-session-hash-04 and session resumption

Emilia Kasper <ekasper@google.com> Mon, 13 April 2015 11:20 UTC

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From: Emilia Kasper <ekasper@google.com>
Date: Mon, 13 Apr 2015 11:20:04 +0000
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To: Karthikeyan Bhargavan <karthik.bhargavan@gmail.com>, Martin Thomson <martin.thomson@gmail.com>
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Cc: "tls@ietf.org" <tls@ietf.org>, Bill Cox <waywardgeek@google.com>
Subject: Re: [TLS] draft-ietf-tls-session-hash-04 and session resumption
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On Mon, 13 Apr 2015 at 10:26 Karthikeyan Bhargavan <
karthik.bhargavan@gmail.com> wrote:

> How about the following:
>       If the original session did not use an extended master secret but
>       the new ClientHello does contain the "extended_master_secret"
>       extension, the server MUST fall back to a full handshake by
>       sending a ServerHello that rejects session resumption and offers a
>       new session.
>

Falling back cannot always be indicated in the ServerHello. In particular,
if the client is resuming with a ticket and without a session ID, then
there is nothing special in the ServerHello that says "resuming/not
resuming".

So I think that David's wording is as precise as you can/need to be there.

Emilia


>
> On 11 Apr 2015, at 03:42, Martin Thomson <martin.thomson@gmail.com> wrote:
>
> > On 10 April 2015 at 16:25, David Benjamin <davidben@chromium.org> wrote:
> >>> If the original session did not use an extended master secret but the
> new
> >>> ClientHello does contain the "extended_master_secret" extension, the
> server
> >>> MUST reject the session and fall back to a full handshake.
> >
> > WFM.
> >
> > ... MUST reject the session *resumption* and fall back ...
> >
> > _______________________________________________
> > TLS mailing list
> > TLS@ietf.org
> > https://www.ietf.org/mailman/listinfo/tls
>
>

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