IETF Logo Mail Archive

Re: [TLS] Padding extension and 0-RTT

Eric Rescorla <ekr@rtfm.com> Sun, 30 October 2016 19:59 UTC

Return-Path: <ekr@rtfm.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 63166128B37 for <tls@ietfa.amsl.com>; Sun, 30 Oct 2016 12:59:10 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.599
X-Spam-Level:
X-Spam-Status: No, score=-2.599 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=rtfm-com.20150623.gappssmtp.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8LumGRKVcVIE for <tls@ietfa.amsl.com>; Sun, 30 Oct 2016 12:59:09 -0700 (PDT)
Received: from mail-yw0-x229.google.com (mail-yw0-x229.google.com [IPv6:2607:f8b0:4002:c05::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 036E412711D for <tls@ietf.org>; Sun, 30 Oct 2016 12:59:09 -0700 (PDT)
Received: by mail-yw0-x229.google.com with SMTP id r204so15766096ywb.0 for <tls@ietf.org>; Sun, 30 Oct 2016 12:59:08 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rtfm-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=oNjGwlbYIaxdO5ci/HDa6TIYck+w/U8tIbYNUYTRE34=; b=ltpBuabq/DVXTHQaHsHnub+WN7zLgNIv08hTreVYq/rmodGpkQ5rbTbkMS7uidsjB9 +z4Y4BvBUk7uUZs4ph4FmFoOpf4DHIiKMV3tbRPz336iUviKzSe2dSStVlIG9zth4kPa d5Tuy9hWfElbw0ERrxHgnkBW1tVtb9MJGMC1E+/SwM3VzTNwUFkDEz46/HnZlxrpN8Zl oxGUsMKY2wDJMpf2mDKdD0S8pSvYZ58SORm6V7JN2kyZriRnxP7jNn0W1vXV05zvrKdC tn7QWt/Jgn693PsrNRdIJ/fvlnk7FZp+3/5AyTTcgYoi9B2cQkE3G8Iazp+CCiKBbpwt KkSg==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=oNjGwlbYIaxdO5ci/HDa6TIYck+w/U8tIbYNUYTRE34=; b=Rh3zLAb/kYY5op/j8Qv8Ycv0vxOPqQMEp3CyOUFrKJH76hcS1L8qWjUrBMWX8PCA11 RYNuWvKoAi2wNp9jzwLq7WyPCT8hP6X6aU8rP0RP+j+DCQAXv3kTS/w3+xE5cYFRkuoo JdP/YmPg3Qetxd2zows441oe2PuEaLkbqVSKLBPuBD+glLDir0KL/enruAJGvwLJWc/1 Hfzahu8qX5blMyDCEWHT9aWO8HieULMsKL8zN1pYPApKkVKEtix+PMtwl47V4IB0jhmj 85Ql9yM2CUEixaA2M3WFlKjP0dPNGRJNoSaJB9IkK/RnpJvHcU4O5Wyux+va3wkRdslq FY7w==
X-Gm-Message-State: ABUngvcS58gFIwCwk8wvvaX9/1y6mph9NEu5L4zR29D/EMpvLIySeSJkT5feaYwRKg7w0/gY6HUwt43fjrd18Q==
X-Received: by 10.129.121.1 with SMTP id u1mr2345647ywc.146.1477857548177; Sun, 30 Oct 2016 12:59:08 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.129.82.210 with HTTP; Sun, 30 Oct 2016 12:58:27 -0700 (PDT)
In-Reply-To: <CAF8qwaC2CBuWyiSrh2uQH7rL50u3n4mUHoEHoKacsAFKURMDFA@mail.gmail.com>
References: <CABkgnnXfJ9+DLZNnF+nZ8z91ce3Hmi-gVNyypcZZpwr_gx3HPA@mail.gmail.com> <CAF8qwaC2CBuWyiSrh2uQH7rL50u3n4mUHoEHoKacsAFKURMDFA@mail.gmail.com>
From: Eric Rescorla <ekr@rtfm.com>
Date: Sun, 30 Oct 2016 12:58:27 -0700
Message-ID: <CABcZeBP6nJqEbwBhPEYFF2_wndtubXmJGFNN4iUUpJgnL2msxQ@mail.gmail.com>
To: David Benjamin <davidben@chromium.org>
Content-Type: multipart/alternative; boundary="94eb2c0a8f82304d4b05401a86cd"
Archived-At: <https://mailarchive.ietf.org/arch/msg/tls/LuePuNEpi_IuwN0Pw7Hh4TKSFGU>
Cc: "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Padding extension and 0-RTT
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: "This is the mailing list for the Transport Layer Security working group of the IETF." <tls.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tls>, <mailto:tls-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tls/>
List-Post: <mailto:tls@ietf.org>
List-Help: <mailto:tls-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tls>, <mailto:tls-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 30 Oct 2016 19:59:10 -0000

I'm ambivalent on this. OTOH, you're technically right, but OTOH it's just
one more conditional to save a few bytes (you need padding to exist
anyway), and if you're doing 0-RTT, you're about to send a lot more bytes
anyway.

-Ekr




On Sun, Oct 30, 2016 at 12:52 PM, David Benjamin <davidben@chromium.org>
wrote:

> Sounds reasonable.
>
> One concern is the F5 bug's failure mode was a timeout rather than an
> error, so, if you take away padding, the allowance in C.3 will not save
> heterogenous deployments where some servers do 1.3 and some are old F5
> servers. But given we're talking about a straight-up server bug now, it
> seems reasonable for a client to say, okay, I will try to account for
> heterogenous 1.2 and 1.3 deployments because that's kinda operationally
> tricky, but if you've got that F5 bug, please fix it already.
>
> David
>
>
> On Sun, Oct 30, 2016 at 6:03 AM Martin Thomson <martin.thomson@gmail.com>
> wrote:
>
> (Trivial optimization warning)
>
> Just perusing my draft and noticed that NSS pads a 0-RTT handshake,
> which is not that surprising given that it's fairly beefy (it will get
> even larger in -18).  Since a 0-RTT handshake will break servers that
> don't at least superficially understand TLS 1.3, maybe we could avoid
> pading in this case.  Is there any reason we shouldn't include that
> advice in the draft?
>
> _______________________________________________
> TLS mailing list
> TLS@ietf.org
> https://www.ietf.org/mailman/listinfo/tls
>
>
> _______________________________________________
> TLS mailing list
> TLS@ietf.org
> https://www.ietf.org/mailman/listinfo/tls
>
>

v2.14.0 | Report a Bug | By Email