Because it wouldn't actually prevent it in this case due to JWT assertion client authentication (a.k.a. private_key_jwt) having come about well before the JWT BCP and the established concept of using the 'typ' header to prevent cross-JWT confusion. Thus there's no validation rule regarding the 'typ' header defined in RFC 7523 for JWT client authentication. Explicitly typing the request object JWT doesn't do anything to prevent it from being used in the context of previously existing JWT applications like client auth.
On Wed, Jul 22, 2020 at 10:32 AM Dominick Baier <dba...@leastprivilege.com> wrote: > Why not use a typ header as suggested by the JWT BCP? > > ——— > Dominick Baier > > On 22. July 2020 at 17:37:41, Brian Campbell ( > bcampbell=40pingidentity....@dmarc.ietf.org) wrote: > > The TL;DR here is a somewhat tentative suggestion that a brief security > consideration be added to > https://datatracker.ietf.org/doc/draft-ietf-oauth-jwsreq/ > <https://datatracker..ietf.org/doc/draft-ietf-oauth-jwsreq/> that > prohibits the inclusion of a 'sub' claim containing the client id value in > the request object JWT so as to prevent the request object JWT (which is > exposed to the user agent) from being erroneously accepted as a valid JWT > for client authentication. > > Some more details and the discussion that led to this here email can be > found at https://github.com/oauthstuff/draft-oauth-par/issues/41 > > *CONFIDENTIALITY NOTICE: This email may contain confidential and > privileged material for the sole use of the intended recipient(s). Any > review, use, distribution or disclosure by others is strictly > prohibited... If you have received this communication in error, please > notify the sender immediately by e-mail and delete the message and any file > attachments from your computer. Thank > you.*_______________________________________________ > > OAuth mailing list > OAuth@ietf.org > https://www.ietf.org/mailman/listinfo/oauth > > -- _CONFIDENTIALITY NOTICE: This email may contain confidential and privileged material for the sole use of the intended recipient(s). Any review, use, distribution or disclosure by others is strictly prohibited. If you have received this communication in error, please notify the sender immediately by e-mail and delete the message and any file attachments from your computer. Thank you._
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