Separate the nonce and IV header parameters

[selfissued]

The description of the “nonce” header parameter in Section 3.1 says that “This parameter holds either a nonce or Initialization Vector value.” Is there a well-understood reason why both a nonce and an initialization vector will never both be needed in the same set of header parameters. Unless such a reason can be documented, please create separate header parameters for “nonce” and “IV”.

[jimsch]

It is not clear that this makes sense. In many cases the IV is described as a nonce value not an IV. An example of this is GCM. It depends on what one things a nonce is as oppose to an IV. How would you characterize a nonce that is not trans-actional, and thus by your criteria it should be place in the content not the wrapper

[jimsch]

Part of pull request cose-wg/cose-spec#98