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

Michael Richardson <mcr@sandelman.ca> Sun, 24 January 2021 05:25 UTC

Return-Path: <mcr@sandelman.ca>
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 978F03A0B29 for <cbor@ietfa.amsl.com>; Sat, 23 Jan 2021 21:25:09 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.898
X-Spam-Level:
X-Spam-Status: No, score=-1.898 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_BLOCKED=0.001, 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 TCYPzfT-1yq8 for <cbor@ietfa.amsl.com>; Sat, 23 Jan 2021 21:25:07 -0800 (PST)
Received: from tuna.sandelman.ca (tuna.sandelman.ca [209.87.249.19]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 5032B3A0B28 for <cbor@ietf.org>; Sat, 23 Jan 2021 21:25:06 -0800 (PST)
Received: from localhost (localhost [127.0.0.1]) by tuna.sandelman.ca (Postfix) with ESMTP id 6C0CE389A2 for <cbor@ietf.org>; Sun, 24 Jan 2021 00:27:17 -0500 (EST)
Received: from tuna.sandelman.ca ([127.0.0.1]) by localhost (localhost [127.0.0.1]) (amavisd-new, port 10024) with LMTP id NuJBsRZpYXIP for <cbor@ietf.org>; Sun, 24 Jan 2021 00:27:15 -0500 (EST)
Received: from sandelman.ca (obiwan.sandelman.ca [IPv6:2607:f0b0:f:2::247]) by tuna.sandelman.ca (Postfix) with ESMTP id E09CD3899F for <cbor@ietf.org>; Sun, 24 Jan 2021 00:27:15 -0500 (EST)
Received: from localhost (localhost [IPv6:::1]) by sandelman.ca (Postfix) with ESMTP id 4E9F8A01 for <cbor@ietf.org>; Sun, 24 Jan 2021 00:25:03 -0500 (EST)
From: Michael Richardson <mcr@sandelman.ca>
To: cbor@ietf.org
In-Reply-To: <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> <A623CBCB-3597-45E7-8A19-DAF4B4F7E46B@tzi.org>
X-Mailer: MH-E 8.6+git; nmh 1.7+dev; GNU Emacs 26.1
X-Face: $\n1pF)h^`}$H>Hk{L"x@)JS7<%Az}5RyS@k9X%29-lHB$Ti.V>2bi.~ehC0; <'$9xN5Ub# z!G,p`nR&p7Fz@^UXIn156S8.~^@MJ*mMsD7=QFeq%AL4m<nPbLgmtKK-5dC@#:k
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable
Date: Sun, 24 Jan 2021 00:25:03 -0500
Message-ID: <20537.1611465903@localhost>
Archived-At: <https://mailarchive.ietf.org/arch/msg/cbor/WGbo7nvAOORfoIzOL0tUpRkzV8c>
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: Sun, 24 Jan 2021 05:25:10 -0000

Carsten Bormann <cabo@tzi.org> wrote:
    > 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.

I don't feel strongly either way.

Also, both the array and the sequence solution result in a solid 8-to-12
bytes of known data at the beginning so file(1) will be very happy.
(ps: It already knows about 55799)

{I've re-implemented my code with a CBOR Sequence, but I'm annoyed that I
haven't found a decode in C that takes a getc(3)-like input stream, and eats
only as many things as it needs.  I have just abandonned tinycbor for QCBOR.}

--
]               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    [