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    JKU in JWT Header

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    • A
      amar.sibia
      last edited by

      Hi,

      We have a 3rd party integration to whom we are sending our JWTs, they have prescribed they need the JKU populated in the JWT header for them to correctly verify the token. I seem to be struggling to find any documentation or mention of how or even if it is possible to configure the jku header in the JWT. Is there a way to get the jku header to be populated correctly?

      FusionAuth™ version 1.22.2

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      • D
        dtokarz1
        last edited by

        I'm sure the support guys will chime in shortly but you can modify the JWT information with lambdas. Here is the link...

        https://fusionauth.io/docs/v1/tech/lambdas/

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        • A
          amar.sibia
          last edited by

          We're already using that to populate claims details, but the documentation implies this is the JWT payload only and not the header

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          • danD
            dan
            last edited by

            You cannot modify JWT headers with a lambda. I can update the documentation to make that clearer.

            Please fee free to file an issue with your use case: https://github.com/fusionauth/fusionauth-issues/issues

            Here's our general roadmap guidance: https://fusionauth.io/docs/v1/tech/core-concepts/roadmap/

            --
            FusionAuth - Auth for devs, built by devs.
            https://fusionauth.io

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            • danD
              dan
              last edited by dan

              I suppose one other option would be for you to have FusionAuth generate the JWT, then proxy the JWT, get the contents, add the JKU header, and then re-sign it. A brief googling indicates Kong can do this, maybe? https://docs.konghq.com/hub/kong-inc/jwt-signer/

              I also updated the documentation to make current limitations clearer: https://github.com/FusionAuth/fusionauth-site/pull/575

              Hope this helps.

              --
              FusionAuth - Auth for devs, built by devs.
              https://fusionauth.io

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              • danD
                dan
                last edited by

                Updated the JWT populate lambda doc to make it clear that headers aren't modifiable at the present time: https://fusionauth.io/docs/v1/tech/lambdas/jwt-populate/

                --
                FusionAuth - Auth for devs, built by devs.
                https://fusionauth.io

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