Re: [TLS] Poly1305 vs GCM
Ilari Liusvaara <ilariliusvaara@welho.com> Thu, 17 December 2015 19:27 UTC
Return-Path: <ilariliusvaara@welho.com>
X-Original-To: tls@ietfa.amsl.com
Delivered-To: tls@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id B5B091B302D for <tls@ietfa.amsl.com>; Thu, 17 Dec 2015 11:27:30 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.91
X-Spam-Level:
X-Spam-Status: No, score=-1.91 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01] 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 nJaCReaXKgAb for <tls@ietfa.amsl.com>; Thu, 17 Dec 2015 11:27:26 -0800 (PST)
Received: from welho-filter1.welho.com (welho-filter1.welho.com [83.102.41.23]) by ietfa.amsl.com (Postfix) with ESMTP id AC2941A8902 for <tls@ietf.org>; Thu, 17 Dec 2015 11:27:26 -0800 (PST)
Received: from localhost (localhost [127.0.0.1]) by welho-filter1.welho.com (Postfix) with ESMTP id C3AB77DF; Thu, 17 Dec 2015 21:27:24 +0200 (EET)
X-Virus-Scanned: Debian amavisd-new at pp.htv.fi
Received: from welho-smtp2.welho.com ([IPv6:::ffff:83.102.41.85]) by localhost (welho-filter1.welho.com [::ffff:83.102.41.23]) (amavisd-new, port 10024) with ESMTP id W91GdXKBwhY7; Thu, 17 Dec 2015 21:27:24 +0200 (EET)
Received: from LK-Perkele-V2 (87-92-35-116.bb.dnainternet.fi [87.92.35.116]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by welho-smtp2.welho.com (Postfix) with ESMTPSA id 814CF1F8; Thu, 17 Dec 2015 21:27:24 +0200 (EET)
Date: Thu, 17 Dec 2015 21:27:20 +0200
From: Ilari Liusvaara <ilariliusvaara@welho.com>
To: James Cloos <cloos@jhcloos.com>
Message-ID: <20151217192720.GA22714@LK-Perkele-V2.elisa-laajakaista.fi>
References: <m31takdh11.fsf@carbon.jhcloos.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Disposition: inline
In-Reply-To: <m31takdh11.fsf@carbon.jhcloos.org>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: ilariliusvaara@welho.com
Archived-At: <http://mailarchive.ietf.org/arch/msg/tls/M1018-OuuVTm9QzcfK8YK-olKWQ>
Cc: tls@ietf.org
Subject: Re: [TLS] Poly1305 vs GCM
X-BeenThere: tls@ietf.org
X-Mailman-Version: 2.1.15
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: Thu, 17 Dec 2015 19:27:30 -0000
On Thu, Dec 17, 2015 at 02:14:18PM -0500, James Cloos wrote: > Given the issues w/ gcm currently under discussion, and that poly1305 > was originally proposed to use w/ aes, should tls recommend aes-poly1305 > instead of aes-gcm for those who want to continue to use aes? > > Or does chacha-poly1305 not fall victim to the 2^36 attack not because > of the aead but rather because of chacha? AFAIK, there are two possible reasons for the difference (one or both may contribute): - Chacha20 is PRF(unction), AES is PRP(ermutation). - Chacha20-Poly1305 has per-packet r and s, AES-Poly1305 and AES-GCM only has per-packet s and per-key r (as originally proposed). -Ilari
- [TLS] Poly1305 vs GCM James Cloos
- Re: [TLS] Poly1305 vs GCM Ilari Liusvaara