Re: [openpgp] v5 in the crypto-refresh draft

Paul Wouters <paul@nohats.ca> Mon, 07 June 2021 18:46 UTC

Return-Path: <paul@nohats.ca>
X-Original-To: openpgp@ietfa.amsl.com
Delivered-To: openpgp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2A93C3A4155 for <openpgp@ietfa.amsl.com>; Mon, 7 Jun 2021 11:46:09 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.097
X-Spam-Level:
X-Spam-Status: No, score=-2.097 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=nohats.ca
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 OkL-oN9a6uzQ for <openpgp@ietfa.amsl.com>; Mon, 7 Jun 2021 11:46:04 -0700 (PDT)
Received: from mx.nohats.ca (mx.nohats.ca [IPv6:2a03:6000:1004:1::68]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 144573A414D for <openpgp@ietf.org>; Mon, 7 Jun 2021 11:46:03 -0700 (PDT)
Received: from localhost (localhost [IPv6:::1]) by mx.nohats.ca (Postfix) with ESMTP id 4FzMl80mbfzKFr; Mon, 7 Jun 2021 20:45:56 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nohats.ca; s=default; t=1623091556; bh=fi63byCiqTRVQeBI9fnwTm/tsFb5wdb4V9KKMAE9k64=; h=Date:From:To:cc:Subject:In-Reply-To:References; b=kAqjpCcq4NjhR99jgTIaUjFTpolNiLzPV/FHYNGf5hO38Ql3CDzjJ+WrjpVZmDcVP dPv9mVwJphcb11HtI2mvR/91TSnZs9ow81mKFmWlz1QH1uCTuuDSFzk3xRiZaRCjAM NmjGXLcKd+ECmxogIZaY0n9I4Ucr/R2QBp0DlO3s=
X-Virus-Scanned: amavisd-new at mx.nohats.ca
Received: from mx.nohats.ca ([IPv6:::1]) by localhost (mx.nohats.ca [IPv6:::1]) (amavisd-new, port 10024) with ESMTP id BkkjgXDLEXJD; Mon, 7 Jun 2021 20:45:55 +0200 (CEST)
Received: from bofh.nohats.ca (bofh.nohats.ca [193.110.157.194]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx.nohats.ca (Postfix) with ESMTPS; Mon, 7 Jun 2021 20:45:55 +0200 (CEST)
Received: by bofh.nohats.ca (Postfix, from userid 1000) id C99CE7E797; Mon, 7 Jun 2021 14:45:53 -0400 (EDT)
Received: from localhost (localhost [127.0.0.1]) by bofh.nohats.ca (Postfix) with ESMTP id C307C7E796; Mon, 7 Jun 2021 14:45:53 -0400 (EDT)
Date: Mon, 7 Jun 2021 14:45:53 -0400 (EDT)
From: Paul Wouters <paul@nohats.ca>
To: Peter Gutmann <pgut001@cs.auckland.ac.nz>
cc: "openpgp@ietf.org" <openpgp@ietf.org>
In-Reply-To: <SY4PR01MB6251D1BBE714F9A161E5AE2AEE389@SY4PR01MB6251.ausprd01.prod.outlook.com>
Message-ID: <3dcadec1-6ff0-911a-ed2-58534d3a2f6@nohats.ca>
References: <SY4PR01MB625176F5D00B0F5F5DE6474DEE399@SY4PR01MB6251.ausprd01.prod.outlook.com>, <d8b9cd22-ded3-4ef3-94c1-7d3ac162b06a@nohats.ca> <SY4PR01MB6251D1BBE714F9A161E5AE2AEE389@SY4PR01MB6251.ausprd01.prod.outlook.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII; format=flowed
Archived-At: <https://mailarchive.ietf.org/arch/msg/openpgp/R7qkR3gZ32FADxPGqVkY6p5kE2A>
Subject: Re: [openpgp] v5 in the crypto-refresh draft
X-BeenThere: openpgp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Ongoing discussion of OpenPGP issues." <openpgp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/openpgp>, <mailto:openpgp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/openpgp/>
List-Post: <mailto:openpgp@ietf.org>
List-Help: <mailto:openpgp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/openpgp>, <mailto:openpgp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 07 Jun 2021 18:46:09 -0000

On Mon, 7 Jun 2021, Peter Gutmann wrote:

>> We are happy to accept such proposed text, please send it to the list :)
>
> Well, if I write it people may be less happy with the text :-).  OK, how
> about, after the paragraph "Note that it is possible for there to be
> collisions of Key IDs", add:

Thanks :)

> -- Snip --
>
> There are no cryptographic issues introduced by this since the fingerprint is
> merely a fixed-length opaque value used to identify the variable-length
> structured data that makes up a public key.  In particular the move to SHA-256
> for V5 fingerprints was made not to address any cryptographic vulnerability
> but to avoid the perception that something insecure might be happening due to
> the use of SHA-1.
>
> -- Snip --

With no hats on, I would probably change the latter bit to:

   In particular the move to SHA-256 for V5 fingerprints was not made to address
   any cryptographic vulnerability, but was made to follow the generic
   guidelines of the cryptograhic community to sunset the use of SHA-1.

This would then also capture other reasons than the one you mention,
such as possible unavailability in crypto libaries or runtime modes
(FIPS) etc etc.

Paul