Allow for single recipient structure to not have array structure

[jimsch]

JOSE now allows for a single recipient to be encoded at the same level as the content. While COSE does not allow for quite the same way of encoding this it would be possible to do something similar.

Current syntax is "recipients : COSE_encrypt_a* | null;" This can be changed to "recipients : COSE_encrypt | COSE_encrypt_a* | null;" Do so would allow for a single recipient to be appended to the end of the current array of values rather than creating two array sub-encodings in CBOR. This encoding saves 2 bytes in the event of a single recipient at the expense of needing to pass in an offset in the array structure when parsing it.

Not really that hard to do from a programmers point of view.

[jimsch]

Open for group discussion

[jimsch]

Based on the messages, there seems to be no support for combining the two maps together into a single map. I have therefore removed that from my working copy of the draft.

There was one request for allowing option b (where a single recipient can be represented as a single map entry rather than as an array of a single map). I have looked at code size, and there does not seem to be a lot of code associated with this option, but as there was no outcry for this option I have not included it.

Unless others have opinions that they believe need to be expressed, I am closing this issue.