jwk toJson should support canonical and/or thumbprint

[Thaina]

Is it possible to add canonicalized function, and/or have GetThumbPrint for jwk class?

[dvsekhvalnov]

Hi @Thaina ,

mind some example usage?

Jwk jwk = new Jwk(
    crv: "P-256",
    x: "BHId3zoDv6pDgOUh8rKdloUZ0YumRTcaVDCppUPoYgk",
    y: "g3QIDhaWEksYtZ9OWjNHn9a6-i_P9o5_NrdISP0VWDU",
    d: "KpTnMOHEpskXvuXHFCfiRtGUHUZ9Dq5CCcZQ-19rYs4"
);

jwk.GetThumbPrint() // ? what it should return for RC, EC, oct types of keys?
jwk.canonicalize() // ? not sure, what shoud it do?

[Thaina]

@dvsekhvalnov My use case is to get thumbprint to verify that it was the same thumbprint as in the server
and the main use case of thumbprint is to set kid in header. As some auth system require it my colleague also decide to have that

And to calculate thumbprint with RFC 7638 is just to hash the canonicalzed public jwk with SHA256 so if the jwk class can return json string in canonicalize form we then can hash it by our own library or even by other low level system or cli

For me I just use EC but I think this library can support all of it? Or just use JwsAlgorithm as parameter?

[dvsekhvalnov]

Ah gotcha, yeah, guess make sense.

Wanna come up with PR or just wait for implementation? Most likely will be next release after upcoming v5.3.0.

Also do you know by chance any existing library that supports it? can use it for cross-testing.

[Thaina]

@dvsekhvalnov I know only in rust (jwt crate) and java jwt use in android

[dvsekhvalnov]

I think Nimbus can have one, ok i'll take a look after v5.3 release. Seems to be pretty straightforward to implement.

[dvsekhvalnov]

Will leave it here as note: https://connect2id.com/products/nimbus-jose-jwt/examples/jwk-thumbprints