Re: [TLS] AD review of draft-ietf-tls-chacha20-poly1305-04

Dave Garrett <> Thu, 10 March 2016 21:03 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id BB6EF12DD88 for <>; Thu, 10 Mar 2016 13:03:15 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.7
X-Spam-Status: No, score=-2.7 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id p6jeENJ1uriP for <>; Thu, 10 Mar 2016 13:03:12 -0800 (PST)
Received: from ( [IPv6:2607:f8b0:400d:c09::231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 9369812DD90 for <>; Thu, 10 Mar 2016 13:02:57 -0800 (PST)
Received: by with SMTP id s5so39835065qkd.0 for <>; Thu, 10 Mar 2016 13:02:57 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20120113; h=from:to:subject:date:user-agent:cc:references:in-reply-to :mime-version:content-transfer-encoding:message-id; bh=HG3mrmVCrMElBCv45KW7eXXJGhjcBJzjNIrhDOub6HQ=; b=FIEFwhiX51vr7ow80o8zbAQMZMMldaIZG7ABFPIfuM1hLCeJ2QNHgJgobQAbzIP40J bZKhWG3V4tZIWbhSNEB/jrJuJbPmwYmJ445FZqAuiXZmendm8yrSU+1UFOeLMea5fTWX 0pxWystqthC+jj7gIOhIX+jMtQprJMmiuI+W6hnis8dJADZW388+MTk/iWLLC/4XrgCq v/XVMHCBbJWif5L1NGVxxg//Y82uWN4pPMv2GTfPHmTJc8Xk8B6Day1Ww0VCaEj2Fwc1 Gl3Qo6N00C0KSb+tZDmghZE9KOahNIeYWZ5VTeJwpq+l75jPhj4F1ggYVG+bjjRHbSd9 065Q==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20130820; h=x-gm-message-state:from:to:subject:date:user-agent:cc:references :in-reply-to:mime-version:content-transfer-encoding:message-id; bh=HG3mrmVCrMElBCv45KW7eXXJGhjcBJzjNIrhDOub6HQ=; b=D9mw/Jo/e00/c1CS0TGL1scI3Fm9q61kGHro5E0FVXOwsCFcVKVAhy5pEhI0c9U3Mv DxkSeOIfIJi6omekpc8y4G/a7/qQKxaEL2XOSdgRAWP4oMznpfgTG8z7efg5ZH3B8K6y N5cH+Yt2gR6/N5HbU1xtBfra0jy9+fayCUXExORPfjDCbL6p161B1OcpAza8zOLKzzyE E9EyuCAboY2VPvg4/tDnyAAZ5BQXkLg7E5jCkB/ABP7SgCr4ooceheVC4R+7N7Ba7hku 2qSd+9YEbXr3GlVUVUkbg7Np0yUEAIlSv7cEKI9BE68ePXH9LDk+NmMNzl/DWyc1yB2q 9zGw==
X-Gm-Message-State: AD7BkJJJDoD7HQGxSNLRRbh88+rGRO7rlOzlneBHYfeP94lvHvXkvjIGJDSDRbl7+RGqMA==
X-Received: by with SMTP id x9mr6974863qka.81.1457643776254; Thu, 10 Mar 2016 13:02:56 -0800 (PST)
Received: from dave-laptop.localnet ( []) by with ESMTPSA id 76sm2478736qhs.21.2016. (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 10 Mar 2016 13:02:55 -0800 (PST)
From: Dave Garrett <>
Date: Thu, 10 Mar 2016 16:02:53 -0500
User-Agent: KMail/1.13.5 (Linux/2.6.32-74-generic-pae; KDE/4.4.5; i686; ; )
References: <>
In-Reply-To: <>
MIME-Version: 1.0
Content-Type: Text/Plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <>
Archived-At: <>
Subject: Re: [TLS] AD review of draft-ietf-tls-chacha20-poly1305-04
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." <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 10 Mar 2016 21:03:16 -0000

On Thursday, March 10, 2016 02:41:58 pm Stephen Farrell wrote:
> My question is: Should the WG take the opportunity to more
> tightly define the key exchange parameters for these
> ciphersuites?
> For example, TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256 could
> REQUIRE RSA keys with >=2048 bit moduli and one could go
> further and say that this also REQUIRES use of specific
> integer DH groups. Etc etc.

This is a good idea that I think is likely to be impractical and could greatly hurt adoption, at least with regard to RSA. Requiring only secure (EC)DHE groups, however, I think is probably worth consideration. Both could be dealt with in a single TLS stack update, but requiring better certs is still a pain for entirely too many (hopefully this won't be true for that much longer).