Support user-defined header claims (e.g. kid)

[benmcollins]

Support user-defined header claims (e.g. kid)

[marek-kuzora]

I would also love to get header parameters support. Right now I have no way of extracting kid from google provided jwt and therefore I don't know which key to use to verify the signature (google jwt structure: https://firebase.google.com/docs/auth/admin/verify-id-tokens).

What's the ETA on fixing this bug?

[benmcollins]

Can you elaborate on what "kid header parameter" is?

Also, check.h is in GNU Check library. You need that in order to compile the test suite (make check)

[benmcollins]

I just looked into this. What I really need to do is allow arbitrary header values. Something that LibJWT doesn't do, at the moment.

[noisy62]

kid is an optional header in JWS standard RFC7515:
4.1.4. "kid" (Key ID) Header Parameter

The "kid" (key ID) Header Parameter is a hint indicating which key
was used to secure the JWS. This parameter allows originators to
explicitly signal a change of key to recipients. The structure of
the "kid" value is unspecified. Its value MUST be a case-sensitive
string. Use of this Header Parameter is OPTIONAL.

When used with a JWK, the "kid" value is used to match a JWK "kid"
parameter value.

a typical Apple Music Developer Token payload is like:
{
"alg": "ES256",
"kid": "ABC123DEFG"
}
{
"iss": "DEF123GHIJ",
"iat": 1437179036,
“exp”: 1493298100
}

For now I will just modify the source by adding a new function with additional parameter based on jwt_encode(). But for the future, it is nice to have the feature for libjwt to be able to add optional headers.

[noisy62]

Hi Ben!
I added a command line utility program amdevtok on the base of libjwt. Modified jwt.h/jwt.c to add 2 customized functions. The work is in a clone: https://github.com/noisy62/amdevtok/blob/master/amdevtok.diff.

IMHO, it will be useful to expand the jwt_t structure to accommodate optional header parameters.

But for this sole purpose of Apple Music Developer Token creation, a little hack is enough. Thanks for your work!!!

[hcngac]

#71 Please review and see if this is useful

[benmcollins]

This is resolved with some commits that were just merged.

[marek-kuzora]

Great, thanks!