[OAUTH-WG] Client Authentication Method at Device Authorization Endpoint

Takahiko Kawasaki <taka@authlete.com> Tue, 04 June 2019 02:10 UTC

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From: Takahiko Kawasaki <taka@authlete.com>
Date: Tue, 4 Jun 2019 11:10:21 +0900
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Subject: [OAUTH-WG] Client Authentication Method at Device Authorization Endpoint
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Hello,

Do you have any plan to define a rule as to which client authentication
method should be used at the device authorization endpoint (which is
defined in OAuth 2.0 Device Authorization Grant
<https://datatracker.ietf.org/doc/draft-ietf-oauth-device-flow/?include_text=1>
)?

Section 4 of CIBA
<https://openid.net/specs/openid-client-initiated-backchannel-authentication-core-1_0.html>,
which has incorporated some ideas/rules/parameters from Device Flow, says
as follows.


*The token_endpoint_auth_method indicates the registered authentication
method for the client to use when making direct requests to the OP,
including requests to both the token endpoint and the backchannel
authentication endpoint.*

This means that a backchannel authentication endpoint in CIBA (which
corresponds to a device authorization endpoint in Device Flow) performs
client authentication using the client authentication method specified by
the token_endpoint_auth_method metadata of the client.

I'd like to know if you have any plan to explicitly add a description like
above into the specification of OAuth 2.0 Device Authorization Grant.

Best Regards,
Takahiko Kawasaki
Authlete, Inc.