Feature: Support for adding more fields into the header, such as x5c, x5t, x5t#S256, etc.

[mgrebenets]

Summary

While creating JWT signed with RSA key it is a standard practice to include the leaf certificate itself as part of JOSE header using "x5c" field.
Additionally, other certs from the chain can be included in "x5c" or their thumbprints can be included into "x5t" or it's variants.

I wouldn't mind being able to add those myself, but currently there doesn't seem to be a way to do so?
Is there actually a way to add custom entries to the JOSE header?
Like --alg not only specifies the signing algorithm but also adds "alg" to header.
I'd need to be able to add "x5c" header entry, for example.

Is it possible or does it require implementation?

[mike-engel]

@mgrebenets it's nos possible right now, but the underlying library does support those headers. Can you provide an example of what would it would look like with the cli?