Support for compressed tokens about jsonwebtoken

[Keats]

I think we want to add crit at least since it's part of JWS. zip is simple and can be deserialize to an enum {Deflate, Other(String)} if we wanted and enc should be an enum as well

[Keats]

Definitely out of scope

[inferiorhumanorgans]

The problem I've run into is that the Header struct doesn't allow access to arbitrary headers (e.g. JWS §4.2, JWE § 4.1) and only allows access to a subset of the defined headers. In this case I'm after the zip header (JWS § 4.1.3) which would allow inflating compressed JWE objects as a external trait.

[Keats]

We could dump all other fields not part of the spec in a hashmap? I'd take a PR for that if that's not a breaking change.

[inferiorhumanorgans]

Sure, however I think there are only two registered headers not covered by the struct: crit (JWS § 4.1.11) and zip (JWE § 4.1.3) so it would come down to whether it's worth potential allocation or if it's worth carrying around a couple extra fields for the most common cases.

[inferiorhumanorgans]

Sounds great.

[Keats]

It would have to come from a PR though, and that's a breaking change