Hi all, In section 4.1 of draft-ietf-oauth-dpop-01, the "jwk" header parameter is REQUIRED. However, there are some cases where "jwk" is not necessary in theory.
For example, consider a case where the client is registered with the Authorization Server, and its one and only public key is also registered with the AS. In that case, when the AS receives a request on Token endpoint, it can just use the public key registered for the client to verify the DPoP Proof. There is no need to send the public key in DPoP Proof. The same goes for requests to the Resource Server, if the AS and RS share the storage for clients' public keys. Things are a little difficult if the AS and RS are separate. Probably the Access Token or its introspection result have to include the public key (instead of its thumbprint as described in section 7). If the client registers multiple keys with the AS, it needs to specify which key it uses to sign the DPoP Proof. However, there is still no absolute need to send the whole key in DPoP Proof. Instead, the client could use "kid" header parameter to specify the key. Daniel Fett once mentioned the above case in the GitHub issue #26 [*1], but I'm not sure what happened to the discussion. There was also a comment on the latest draft about the "jwk" header parameter [*2]. I agree with using the same DPoP Proof structure for requests to AS and RS, but I think there are some cases where we can omit "jwk" in BOTH requests. Making "jwk" OPTIONAL would allow those cases to reduce some messaging overhead. I'd like to hear your opinions about it. [*1]: https://github.com/danielfett/draft-dpop/issues/26#issuecomment-480701746 [*2]: https://mailarchive.ietf.org/arch/msg/oauth/smwsONA6c4H2UICcZMzb8Yv2QRc/ Best regards, Toshio Ito ------------- Toshio Ito Research and Development Center Toshiba Corporation _______________________________________________ OAuth mailing list OAuth@ietf.org https://www.ietf.org/mailman/listinfo/oauth
