Support for custom `use` (Public Key Use)

[Kaveen Rodrigo]

Hi, currently the library only supports sig and enc for use but as the RFC 7517 specification says

   Other values MAY be used.  The "use" value is a case-sensitive
   string.  Use of the "use" member is OPTIONAL, unless the application
   requires its presence.

Any chance this would be supported as currently, it throws errors when trying to parse a JWKSet using JWKSet.load

java.text.ParseException: Invalid JWK at position 1: Invalid JWK use: tls
    at com.nimbusds.jose.jwk.JWKSet.parse(JWKSet.java:337)
    at com.nimbusds.jose.jwk.JWKSet.parse(JWKSet.java:302)
    at com.nimbusds.jose.jwk.JWKSet.load(JWKSet.java:402)
    at com.nimbusds.jose.jwk.JWKSet.load(JWKSet.java:420)

[Vladimir Dzhuvinov]

You're right. Would be interested in submitting a PR? :)

[Kaveen Rodrigo]

Hey Vladimir,

What do you think is the best approach to solving this, removing the enum foruse selection?

[Owen O Byrne]

Hi Vladimir, Kaveen, Are you working on an OpenBanking implementation Kaveen - I'm having the same problem.

I changed the KeyUse class from an Enum to a String, but left the two enum values as static strings so they can still be used throughout the rest of the code.

This change affected a lot of the code, but the tests seems to be OK. I added 3 extra tests - 2 to validate that keys can be generated with custom values, and one to check that keys with custom values can be parsed.

I create a pull request https://bitbucket.org/connect2id/nimbus-jose-jwt/pull-requests/45/changes-to-allow-custom-values-for-the-use/diff

I hope this is a sensible change - I'd love your feedback. Thanks Owen

[Vladimir Dzhuvinov]

Thanks!

Since we have a breaking change, this will require a new major release. Not a problem though. I'll look at the code.

[Kaveen Rodrigo]

Hey Owen,

Guilty as charged, you know exactly the problem I'm hung on as well. I'll also take a look at it. Feel a tad bit bad as I've already made my own JWK models and parser.

cheers, Kaveen

[Vladimir Dzhuvinov]

I looked at the PR. I'm thinking of keeping the KeyUse class, to benefit from type safety. It just won't be an enum, to allow other values.

[Vladimir Dzhuvinov]

It there an official spec that defines the "tls" key type?

[Vladimir Dzhuvinov]

Commit f4d3069

The non-enum class change turned out to touch just a few lines of code.

Should be pushed out to Maven Central as v7 in a few minutes.

Happy coding!

[Owen O Byrne]

Ah yeah, that's a much better way! Thanks Vladimir!

I don't think 'tls' is a public value - it's a proprietary value being used by the Open Banking standard to differentiate between keys used for TLS encryption, and those used for data encryption.

[Kaveen Rodrigo]

Thanks, Vladimir!

A much better solution, I'll take a look at this. As per tls key type, as Owen said it's an Open Banking UK specific use.

cheers, Kaveen Rodrigo

[Vladimir Dzhuvinov]

Thanks for clarifying the tls :)