[Cbor] Interactions of packed CBOR and tags

Jim Schaad <ietf@augustcellars.com> Thu, 27 August 2020 21:00 UTC

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From: Jim Schaad <ietf@augustcellars.com>
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Date: Thu, 27 Aug 2020 14:00:48 -0700
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Subject: [Cbor] Interactions of packed CBOR and tags
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While building a test library of strings for evaluating my algorithm, I
ended up with a question of how tags interact with the idea of CBOR packing.
Specifically, if I use a standard date/time string with tag 0, should that
text string be considered as a candidate for packing?

0("1970-01-01T00:00Z") could potentially be compressed to 0(simple(3))

The problem is that this is no longer a valid CBOR encoding so it would not
seem to be a legal thing to do.

Question:  Must packed CBOR be valid CBOR or does that requirement only
apply to unpacked CBOR?