Re: [TLS] '15 TLS Fall Interim Minutes

Adam Langley <> Wed, 23 September 2015 15:54 UTC

Return-Path: <>
Received: from localhost ( []) by (Postfix) with ESMTP id 5224E1A8709 for <>; Wed, 23 Sep 2015 08:54:57 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.278
X-Spam-Status: No, score=-1.278 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, FM_FORGED_GMAIL=0.622, FREEMAIL_FROM=0.001, SPF_PASS=-0.001] autolearn=no
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id Q8pHsJQT3j81 for <>; Wed, 23 Sep 2015 08:54:55 -0700 (PDT)
Received: from ( [IPv6:2a00:1450:4010:c03::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 716F91A8703 for <>; Wed, 23 Sep 2015 08:54:55 -0700 (PDT)
Received: by lahg1 with SMTP id g1so56274752lah.1 for <>; Wed, 23 Sep 2015 08:54:53 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=ZzmaoTK5ewukoL2y4/dO5dRAnC2fhSuRcjUE608imHo=; b=sucH66uswxZoWycgIYN8DfGciEbtFq4cElVNJllnp5XdtXYikKT/zQ6GdQTt5KmhWE IJp0Wz3KLPB8GCGxoBPoQENK59MBkjDI+mSnXmy6NL8wxHrqf7B+OMU2To/eRB+xAf76 5auzOvHcZkv1hPYVP0OoDNNkCfFZrwCKEQrgr50tTqs4T4osgnYYy2y4SLUyDfCNHtdq JmZbKIvm7Obnmy3LsnEaka0C3hTv497PfvPvHmnzkquM+04AGcaFB6ox9zakvs53Nb5d X1P1UfPqW0tUbCQyBxBqI6KqBbrrNQR+s1UN+CRe5E9ROKv5OOtv7NwOlMeJ+hzKHfiN xazQ==
MIME-Version: 1.0
X-Received: by with SMTP id xj2mr11932702lbb.124.1443023693504; Wed, 23 Sep 2015 08:54:53 -0700 (PDT)
Received: by with HTTP; Wed, 23 Sep 2015 08:54:53 -0700 (PDT)
In-Reply-To: <20150923105439.GA24394@LK-Perkele-VII>
References: <> <20150923105439.GA24394@LK-Perkele-VII>
Date: Wed, 23 Sep 2015 08:54:53 -0700
X-Google-Sender-Auth: _HZr0rpVu94_amYTx1xzTprf4F8
Message-ID: <>
From: Adam Langley <>
To: Ilari Liusvaara <>
Content-Type: text/plain; charset="UTF-8"
Archived-At: <>
Cc: "" <>
Subject: Re: [TLS] '15 TLS Fall Interim Minutes
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: "This is the mailing list for the Transport Layer Security working group of the IETF." <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 23 Sep 2015 15:54:57 -0000

On Wed, Sep 23, 2015 at 3:54 AM, Ilari Liusvaara
<> wrote:
> One thing to note: The time is 4 octets, and 32 bit time since unix
> epoch runs out a good bit faster than what I would like.

It's an unsigned value so it stretches until 2106 rather than the
standard epoch rollover at least.

>> investigate: using the same construct for server/client sigs.
> Huh? Don't both currently use the same construct, except for the
> context string? Are you proposing to remove the context string or
> what?

The on-the-fly client auth messages were envisioned to sign the
certificate and a TLS Exporter value. That point was reflecting a
desire to have the handshake signatures sign the same thing if that
makes sense.

>> 4. We agreed to not allow unsolicited client auth.
> What will browser using HTTP/2 do if it receives client reauth request
> when it has stream blocking identity change open?
> - Open new connection and ??? to elict certificate request.
> - Reset all streams that block identity change and then change identity.
> - Reset all streams, change identity and retry request.
> - Kill connection (e.g. PROTOCOL_ERROR).
> (Just changing the identity is known to be insecure.)

"Unsolicited" means that the TLS server never sent an on-the-fly

So the HTTP/2 situation would involve the server sending a
CertificateRequest which includes an opaque identifier. The
application protocol is free to decide that that identifier means and
HTTP/2 can decide that it's the stream id of the request that
triggered the need for a certificate. The client returns a certificate
(empty or not) and, in the mean time, the connection can continue
flowing. (And other CertificateRequests can be sent while one is

>> 6. We want a consolidated certificate message and certificate verify.
> Just be careful that certificate is still signed, as many signature
> algorithms fail to even properly bind the key, and nothing binds the
> certificate.

Yes, that's understood.

> Parse error. Does this mean something like "how much data current
> ciphers can safely encrypt"?


> Huh? This is about collisions between different hash algorithms. I
> don't see how contributory behavior would help there (which is severly
> limited by 1RTT maximum there).

I think we quite possibly didn't understand the concern here. Could
you spell it out at more length?



Adam Langley