IETF Logo Mail Archive

Re: [Cfrg] Curve manipulation, revisited

Benjamin Black <b@b3k.us> Mon, 29 December 2014 21:48 UTC

Return-Path: <b@b3k.us>
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 AC12E1ACDB2 for <cfrg@ietfa.amsl.com>; Mon, 29 Dec 2014 13:48:05 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.977
X-Spam-Level:
X-Spam-Status: No, score=-1.977 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, FM_FORGED_GMAIL=0.622, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7] 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 DBPTH7MVB54e for <cfrg@ietfa.amsl.com>; Mon, 29 Dec 2014 13:48:04 -0800 (PST)
Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 6FE041A90EC for <cfrg@irtf.org>; Mon, 29 Dec 2014 13:47:58 -0800 (PST)
Received: by mail-wi0-f177.google.com with SMTP id l15so23132004wiw.4 for <cfrg@irtf.org>; Mon, 29 Dec 2014 13:47:57 -0800 (PST)
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:content-type; bh=U4rtmoJG6ZkaY9CIT7Ydqmk/Vm1WutmnOxbxSmb30YY=; b=bANp9aOh4JQRn59/nY5FI8I/3Q4VIQmnNOSyTYXz+XyJi7fgXr9iHwZdCCkQ7ruFkB 18RasF615yY0rIXnLWhnXNYixUGPnhRivKaCCvnpxzIV5tUy+1BBWvc5F6G0xzGt5siG yG2/+yBTuaQOg3UalalpXikFFiqU9pT1X7KjKGuZYeSofBHGI7YvuRTAYmoSblOF+yiU hqE/deX8Mr/P94FWVZiu3hCgDyAF8A4GNbVgDVFzwGBrihzctNniECxl+uvmH6qr+9uO xRzt6SQci1FV06P1XF1FHgN67FVhL41lEtN2GZrCc8oVVgBiDodlDMbKO3tmXQ2kAwjX hTeA==
X-Gm-Message-State: ALoCoQkBLkdNRGfW6xZDvcFaGfs/RSvcAloqJcDOIAtg1lpJwJXspWLcIF1TgXLV1I8TRPNlHgKd
X-Received: by 10.194.71.203 with SMTP id x11mr115431443wju.131.1419889677070; Mon, 29 Dec 2014 13:47:57 -0800 (PST)
MIME-Version: 1.0
Received: by 10.216.190.139 with HTTP; Mon, 29 Dec 2014 13:47:36 -0800 (PST)
In-Reply-To: <CACsn0c=Xc2Qp4QBFUSUL38iQoDd3554Ukw2nMRGfiUoeTN0d9Q@mail.gmail.com>
References: <CAMfhd9W684XMmXn3ueDmwrsQ_ZdiFG+VqYLxkvs7qDwiJdpk6w@mail.gmail.com> <1725646678.805875.1419539885135.JavaMail.yahoo@jws100115.mail.ne1.yahoo.com> <CAMfhd9Ua5fFZk46Xx1AN2VgyJ=Yng6fnO8aN-_ZfzXQn0Xbxhg@mail.gmail.com> <CA+Vbu7zqFcu8d1053mZ_eEm0q=np6T3snSQ4rfY0k1-4hBVDsA@mail.gmail.com> <CACsn0ck1tJ5USLza_kFwBr94RqS6KfczHA2yR-v4opFC3o4dDQ@mail.gmail.com> <CA+Vbu7wDMR9RdFAouxpVfrSwU0xV2s0N=DHZ+xO9afcNQpH9ZQ@mail.gmail.com> <CACsn0c=Xc2Qp4QBFUSUL38iQoDd3554Ukw2nMRGfiUoeTN0d9Q@mail.gmail.com>
From: Benjamin Black <b@b3k.us>
Date: Mon, 29 Dec 2014 13:47:36 -0800
Message-ID: <CA+Vbu7y3JNExqJV2LttfPJLSAxN3SDmaga-eFtRzVfM9-WaZcw@mail.gmail.com>
To: Watson Ladd <watsonbladd@gmail.com>
Content-Type: multipart/alternative; boundary="047d7bfd0bd2d28ccb050b61d3c7"
Archived-At: http://mailarchive.ietf.org/arch/msg/cfrg/EibRqHfS83rjL0kHQtooCjCI4eg
Cc: "cfrg@irtf.org" <cfrg@irtf.org>
Subject: Re: [Cfrg] Curve manipulation, revisited
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: Mon, 29 Dec 2014 21:48:05 -0000

On Mon, Dec 29, 2014 at 12:04 PM, Watson Ladd <watsonbladd@gmail.com> wrote:

>
> You are correct, I meant 2^384-big vs. 2^383-31 or 2^389-21. But
> neither of these are as good as 2^448-2^224-1: there are no good
> choices of prime around 2^384. I and Mike Hamburg gave 2^389-21 a try,
> and we couldn't compare to your listed numbers for 2^384-big directly:
> I think we concluded they were in the same ballpark. We can get a lot
> more security for very little drop in speed with 2^448-2^224-1.
>
>
How far from 2^384 did you look? I think it would be useful to the group to
know which candidates were considered and why they were rejected.


b

v2.23.0 | Report a Bug | By Email