CBOR tagged data can't be deserialized

[wkornewald]

Describe the bug

When you have CBOR data that is tagged, deserialization fails with an exception. With tags I'm referring to section 3.4 of the RFC:

https://datatracker.ietf.org/doc/html/rfc8949#section-3.4

In our case for the CovPass / covid vaccination certificate app some countries use tag 0 to annotate strings as being in date/time format.

The other issue is that we can't decode the COSE data format because the array is tagged with 18:

https://cose-wg.github.io/cose-spec/#rfc.appendix.C.2.1

1. By default, tags should just be ignored during deserialization.
2. We could need an annotation that a certain tag should be used for serialization and optionally also be required during deserialization.
3. For more dynamic tagging something like a special CborTagged(tag, data) object would be nice which allows extracting arbitrary tags (or null) during deserialization and setting arbitrary tags during serialization.

Environment

• Kotlin version: 1.5.10
• Library version: 1.2.1

[sandwwraith]

Does #1614 solve this? It ignores tags by default

[wkornewald]

Not really. We need to be able to work with the tags, i.e. match them or extract them and set them.

[sandwwraith]

I'll leave this open then

[JesusMcCloud]

see #2412