Re: [dns-privacy] [TLS] Martin Duke's No Objection on draft-ietf-dprive-xfr-over-tls-11: (with COMMENT)

Eric Rescorla <> Thu, 29 April 2021 19:03 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id D3D1F3A15E7 for <>; Thu, 29 Apr 2021 12:03:29 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.896
X-Spam-Status: No, score=-1.896 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=unavailable autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id aYvnfkWsKEpi for <>; Thu, 29 Apr 2021 12:03:25 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:4864:20::d36]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id B653F3A1534 for <>; Thu, 29 Apr 2021 12:02:43 -0700 (PDT)
Received: by with SMTP id g125so11929856iof.3 for <>; Thu, 29 Apr 2021 12:02:43 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EJoPvyn9PVMUge5LvwMz5prE7c21uC2z01RqjxaCGPc=; b=FNdMoWRmIGkc+4w/0TUgt7HkSOPdzR/1Jw6hVtzFDgdSJyqCCz1QMubtIZnaG80IGN i8wZkl9DwrSh3pkWT912ZEJtlSzenit0Inn/PnOjP2d3oydBCUtte+nx9sCicBJA0XlL rWzzPlgalbus/BhL5q6C6zKf8kJvM1mhmTr21uu1diMzEwRs+1D5jZmOLZKTLYBtg54h UamWzDzWPYR+UAHAHjm5iRAC2/Qh1PtBzp734qEBMUY6r6s3PQrg4DrpE65rA+mshfGR 4DKMxk9L8fdly0u2Z2QEnzkaD1iYogYgMRspLDG13DFTH1Ye7zDM6D2yyc92OuvYhusi /R9A==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EJoPvyn9PVMUge5LvwMz5prE7c21uC2z01RqjxaCGPc=; b=IwvjCqlmCEJlJJNgQGlXOuqPv6bE9kxtclchOOXGLzXc3V94iL0nq4JUbqnCBqY6Xl LhrdC7PU5KfiH74MbJ9Z6iBhmJriNGIDdzmoSRwITCbTfBnWzkDrKTWr0adl+qpOD5Hg 4GXgEf60QkCcW+8E0UssPTwq7y/NWTI6OORoaUEKct+8AYHQnQYTkH/KzEmC/U0MglKf 5HkdF3jPYbu4w6c3VIXeTvklihDlpKrpbjCNFbBZEKUljEBSlgv0doZKU3pFwQt3VMPy N4xtYS45SCmQeZJKKDtxkthYFXGm1CoT8HjJos8xCt8bdUXpozMoepEb/zZ6nQ1j3lrJ rUBw==
X-Gm-Message-State: AOAM532z2lVUONAapC84wY1QIPJreWlH9+XwBnkLwc8k/ci41LEidQ6x 9SDSz3cGFZRVknjPwYrrRkd5/pHuHOBnGJCT0jwxGQ==
X-Google-Smtp-Source: ABdhPJxxyrM37WlwZ+zR5vgRuATl0Sw09WaKMQJ1835JFciROHj6tx+/R3fqPyG/K6V8MR/oL4Fm1lUxcevZukjXamg=
X-Received: by 2002:a02:cab3:: with SMTP id e19mr456149jap.64.1619722962382; Thu, 29 Apr 2021 12:02:42 -0700 (PDT)
MIME-Version: 1.0
References: <> <> <> <> <> <>
In-Reply-To: <>
From: Eric Rescorla <>
Date: Thu, 29 Apr 2021 12:02:06 -0700
Message-ID: <>
To: Allison Mankin <>
Cc: "Salz, Rich" <>, "" <>, "" <>
Content-Type: multipart/alternative; boundary="000000000000cec5a205c121237d"
Archived-At: <>
Subject: Re: [dns-privacy] [TLS] Martin Duke's No Objection on draft-ietf-dprive-xfr-over-tls-11: (with COMMENT)
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 29 Apr 2021 19:03:36 -0000

On Thu, Apr 29, 2021 at 11:49 AM Allison Mankin <>

> Hi Ekr,
> As Sara wrote, the spec had ALPN. The WG consensus during the IETF 108
> meeting was very strong to take it out, including quite strong statements
> from you along the lines that distinguishing between XoT and DOT was an
> incorrect usage of ALPN.

I don't have the message you are referring to at hand, so I'm not able to
respond to that. However, I don't believe that an ALPN is needed to
distinguish XoT from DoT because there is no confusion between the protocol
traces of XoT and DoT. However there should be an ALPN to distinguish XoT
and DoT from HTTP, SMTP, etc.IOW, this protocol should use ALPN="dot".

I understand that the perspective changed since IETF108 (that WG discussion
> was at the end of July 2020) and that communications were not wide enough
> for us to know about it in March when the WG moved the draft to WGLC,
> Directorates Review, and IETF LC

I don't think anyone is saying that the WG somehow did something wrong
procedurally, merely that this is a defect that ought to be corrected prior
to publication.


On Thu, Apr 29, 2021 at 14:25 Eric Rescorla <> wrote:
>> Probably not, but I agree with MT.
>> The general idea here is that any given protocol trace should only be
>> interpretable in one way. So, either you need the interior protocol to be
>> self-describing or you need to separate the domains with ALPN. I don't
>> believe that either the IP ACL or mTLS addresses this issue, and in fact
>> arguably mTLS makes the problem worse because it provides authenticated
>> protocol traces which might be usable for cross-protocol attacks.
>> -Ekr
>> On Thu, Apr 29, 2021 at 7:26 AM Salz, Rich <rsalz=
>>> wrote:
>>> >    No new protocol should use TLS without ALPN.  It only opens space
>>> for cross-protocol attacks.  Did the working group consider this
>>> possibility in their discussions?
>>> I don't believe that message has been made as public as it should be.
>>> _______________________________________________
>>> dns-privacy mailing list
>> _______________________________________________
>> TLS mailing list