[Cbor] Invalid Tag Values

Kio Smallwood <kio@mothers-arms.co.uk> Thu, 24 June 2021 19:15 UTC

Return-Path: <kio@mothers-arms.co.uk>
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 BD5A33A27F5 for <cbor@ietfa.amsl.com>; Thu, 24 Jun 2021 12:15:52 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.498
X-Spam-Level:
X-Spam-Status: No, score=-1.498 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, HTML_MESSAGE=0.001, KHOP_HELO_FCRDNS=0.398, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=no 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 15zIHydoylkA for <cbor@ietfa.amsl.com>; Thu, 24 Jun 2021 12:15:48 -0700 (PDT)
Received: from authenticated.a-painless.mh.aa.net.uk (painless-a.thn.aa.net.uk [IPv6:2001:8b0:0:62::26]) (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 AD0163A28A7 for <cbor@ietf.org>; Thu, 24 Jun 2021 12:15:23 -0700 (PDT)
Received: from a-webmail.thn.aa.net.uk ([2001:8b0:0:62::22] helo=webmail.aa.net.uk) by painless-a.thn.aa.net.uk with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from <kio@mothers-arms.co.uk>) id 1lwUor-0001kR-6r for cbor@ietf.org; Thu, 24 Jun 2021 20:15:21 +0100
Received: from cpc105076-sgyl40-2-0-cust233.18-2.cable.virginm.net ([82.4.24.234]) by webmail.aa.net.uk with HTTP (HTTP/1.1 POST); Thu, 24 Jun 2021 20:15:16 +0100
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="=_e5e10275bd8513984f2477cb1713655f"
Date: Thu, 24 Jun 2021 20:15:16 +0100
From: Kio Smallwood <kio@mothers-arms.co.uk>
To: cbor@ietf.org
Message-ID: <f5650d87a36b10f6b75d2a1123f84bb5@mothers-arms.co.uk>
X-Sender: kio@mothers-arms.co.uk
User-Agent: Roundcube Webmail/1.3.16
Archived-At: <https://mailarchive.ietf.org/arch/msg/cbor/Pn0PKyViq4n5ohWO2bxLd4yemo8>
Subject: [Cbor] Invalid Tag Values
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: Thu, 24 Jun 2021 19:15:53 -0000

Hi All, 

I'm having trouble understanding the rationale of intentionally invalid
tags as documented here[1] 

Under what circumstances would an encoder produce these tags and what
should a decoder do when encountering them? Since I'm working on that
part of the decoder[2] anyway I thought I'd better check. 

Thanks, 

Kio 

[1]
https://www.ietf.org/archive/id/draft-bormann-cbor-notable-tags-03.html#section-toc.1-1.10.2.1.1


[2] https://github.com/agronholm/cbor2/pull/115