[Cfrg] Is draft-agl-cfrgcurve-00 incompatible with Ed25519?

Tony Arcieri <bascule@gmail.com> Fri, 09 January 2015 23:11 UTC

Return-Path: <bascule@gmail.com>
X-Original-To: cfrg@ietfa.amsl.com
Delivered-To: cfrg@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 30C481A1AAE for <cfrg@ietfa.amsl.com>; Fri, 9 Jan 2015 15:11:50 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.999
X-Spam-Level:
X-Spam-Status: No, score=-1.999 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, HTML_MESSAGE=0.001, SPF_PASS=-0.001] autolearn=ham
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 Shp3jL0SisfT for <cfrg@ietfa.amsl.com>; Fri, 9 Jan 2015 15:11:48 -0800 (PST)
Received: from mail-ob0-x22a.google.com (mail-ob0-x22a.google.com [IPv6:2607:f8b0:4003:c01::22a]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id E03C91A1AEB for <cfrg@irtf.org>; Fri, 9 Jan 2015 15:10:58 -0800 (PST)
Received: by mail-ob0-f170.google.com with SMTP id wp18so15478037obc.1 for <cfrg@irtf.org>; Fri, 09 Jan 2015 15:10:58 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:from:date:message-id:subject:to:content-type; bh=9fflF3ncDmukwBqcqo1YFiMXxrgNPl8Vc48PyMXq+9g=; b=Dl4DdWEV3NsDGet/mhg8CRkfsEwbTupfxlUCPqEc7ScFtkw9dxbOtAkYnKzE/2Qc19 TFrFCdmKo7HPMxIKNtbAEG/2rMP0xMk02pWL7nOWjKth541Zjw/Ihfb74oUSele+H12Z GC/qW3lmOBMunwFW3lHXAD/yP6VjWSEYCGBKZGr6VH9/EHVQgK9BoOtFnrdVEghXXL5A 3Q7GpqshccLC7fyk8k+dzaIhhPXLp5yjk7wKrbBE2RRmKoD6QFguN9Y/iXfPDPAEIsj0 Bxx9fIErqpKnErhN0FZcLag/Xxii8BMuFWqP4D2WphexBrc8/p2oNj2MT2Z0yCPXONCK mbzQ==
X-Received: by 10.202.230.145 with SMTP id d139mr10435305oih.8.1420845058032; Fri, 09 Jan 2015 15:10:58 -0800 (PST)
MIME-Version: 1.0
Received: by 10.60.227.225 with HTTP; Fri, 9 Jan 2015 15:10:37 -0800 (PST)
From: Tony Arcieri <bascule@gmail.com>
Date: Fri, 09 Jan 2015 15:10:37 -0800
Message-ID: <CAHOTMV+xQV6uqp-tB1Hs8xry5L+od=UW7RgtRYY-Lte4SGwxHA@mail.gmail.com>
To: "cfrg@irtf.org" <cfrg@irtf.org>
Content-Type: multipart/alternative; boundary="001a1141745af759b7050c40443b"
Archived-At: <http://mailarchive.ietf.org/arch/msg/cfrg/3Tf6s8h1eAnxb1dccfzDqchOOf4>
Subject: [Cfrg] Is draft-agl-cfrgcurve-00 incompatible with Ed25519?
X-BeenThere: cfrg@irtf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Crypto Forum Research Group <cfrg.irtf.org>
List-Unsubscribe: <http://www.irtf.org/mailman/options/cfrg>, <mailto:cfrg-request@irtf.org?subject=unsubscribe>
List-Archive: <http://www.irtf.org/mail-archive/web/cfrg/>
List-Post: <mailto:cfrg@irtf.org>
List-Help: <mailto:cfrg-request@irtf.org?subject=help>
List-Subscribe: <http://www.irtf.org/mailman/listinfo/cfrg>, <mailto:cfrg-request@irtf.org?subject=subscribe>
X-List-Received-Date: Fri, 09 Jan 2015 23:11:50 -0000

It would be good to get a definitive answer on this question before
draft-agl-cfrgcurve-00 adopted (which I'm guessing is likely to happen)

For clarity: I like draft-agl-cfrgcurve-00 and I hope it does get adopted.
I would simply like the CFRG to have the option to adopt Ed25519 in the
future. I am not necessarily saying the CFRG *should* adopt Ed25519
wholesale. However I would like for the CFRG to specifically address this
question in advance in anticipation of it coming up in the future.

If Ed25519 is incompatible with draft-agl-cfrgcurve-00, I would suggest
that drafg-agl-cfrgcurve-00 be specifically amended to include the
possibility of using Ed25519 for signatures in the future.

Ed25519 is already being deployed in SSH and OpenPGP contexts, so I hope
the CFRG would not accidentally rule it out in the name of "compromise".
Having similar-but-incompatible Edwards curves used in different protocol
contexts sounds like a recipe for disaster.

--
Tony Arcieri