Re: [Cbor] [COSE] CBOR magic number, file format and tags

Carsten Bormann <cabo@tzi.org> Sat, 23 January 2021 22:54 UTC

Return-Path: <cabo@tzi.org>
X-Original-To: cbor@ietfa.amsl.com
Delivered-To: cbor@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id EFF203A0D02 for <cbor@ietfa.amsl.com>; Sat, 23 Jan 2021 14:54:43 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.919
X-Spam-Level:
X-Spam-Status: No, score=-1.919 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
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 Dh7Bv0IoqR25 for <cbor@ietfa.amsl.com>; Sat, 23 Jan 2021 14:54:41 -0800 (PST)
Received: from gabriel-vm-2.zfn.uni-bremen.de (gabriel-vm-2.zfn.uni-bremen.de [134.102.50.17]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 1F8153A0A9E for <cbor@ietf.org>; Sat, 23 Jan 2021 14:54:40 -0800 (PST)
Received: from [192.168.217.118] (p548dc939.dip0.t-ipconnect.de [84.141.201.57]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gabriel-vm-2.zfn.uni-bremen.de (Postfix) with ESMTPSA id 4DNWfQ2dg8zySd; Sat, 23 Jan 2021 23:54:38 +0100 (CET)
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.4\))
From: Carsten Bormann <cabo@tzi.org>
In-Reply-To: <16948.1611441956@localhost>
Date: Sat, 23 Jan 2021 23:54:37 +0100
Cc: "Dale R. Worley" <worley@ariadne.com>, cbor@ietf.org, doug@ewellic.org
X-Mao-Original-Outgoing-Id: 633135277.751929-74e892c24b49d94f76edc7680aa0500f
Content-Transfer-Encoding: quoted-printable
Message-Id: <A623CBCB-3597-45E7-8A19-DAF4B4F7E46B@tzi.org>
References: <87wnw49wez.fsf@hobgoblin.ariadne.com> <3DD6CB17-103F-48BF-A4EF-B2AEF1573C93@tzi.org> <30869.1611432082@localhost> <DCCD03C2-8F1C-4AD4-A9B2-D58D2F3016E2@tzi.org> <30257.1611437964@localhost> <71FC9F96-DAF1-4F8E-86F3-84F7162F8D05@tzi.org> <16948.1611441956@localhost>
To: Michael Richardson <mcr@sandelman.ca>
X-Mailer: Apple Mail (2.3608.120.23.2.4)
Archived-At: <https://mailarchive.ietf.org/arch/msg/cbor/fqjtL98AesrK8YtJSWxsXToF4Io>
Subject: Re: [Cbor] [COSE] CBOR magic number, file format and tags
X-BeenThere: cbor@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Concise Binary Object Representation \(CBOR\)" <cbor.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/cbor>, <mailto:cbor-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/cbor/>
List-Post: <mailto:cbor@ietf.org>
List-Help: <mailto:cbor-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/cbor>, <mailto:cbor-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sat, 23 Jan 2021 22:54:44 -0000

OK, so you always get the CBOR sequence solution, you just don’t always send it naked (as a CBOR sequence), put sometimes wrapped in an array.

Grüße, Carsten


> On 2021-01-23, at 23:45, Michael Richardson <mcr@sandelman.ca> wrote:
> 
> 
> Carsten Bormann <cabo@tzi.org> wrote:
>>> It just avoids the CBOR Sequence.  The first element is something.  It
>>> can be a CBOR Tag<CBOR>.  The real item is second element.
> 
>> I’m still intrigued.  So why not just put the tag on the data item to
>> be tagged?
> 
> For content that the application doesn't really know a lot about,
> (a CBOR compressed certificate for instance), then the second element is
> always the thing transmitted.  (With whatever tags are there!)
> 
> The application doesn't have to have such intimate knowledge about whether or
> not to send the tags.
> 
> --
> ]               Never tell me the odds!                 | ipv6 mesh networks [
> ]   Michael Richardson, Sandelman Software Works        |    IoT architect   [
> ]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [
>