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OAuth 2.0 Delegated Authorization
draft-li-oauth-delegated-authorization-01

Document Type Active Internet-Draft (individual)
Authors Li Ruochen , Haiguang Wang , Peter Chunchi Liu , Tieyan Li
Last updated 2026-03-02
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draft-li-oauth-delegated-authorization-01
oauth                                                              R. Li
Internet-Draft                                                   H. Wang
Intended status: Informational                       Huawei Int. Pte Ltd
Expires: 3 September 2026                                         C. Liu
                                                     Huawei Technologies
                                                                   T. Li
                                                     Huawei Int. Pte Ltd
                                                            2 March 2026

                   OAuth 2.0 Delegated Authorization
               draft-li-oauth-delegated-authorization-01

Abstract

   Delegated authorization enables a client to delegate a subset of its
   granted privileges to a subordinate access token (also known as a
   delegated access token).  This mechanism allows the client to
   securely delegate authorization to a delegated party while
   maintaining fine-grained control over delegated permissions.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://liuchunchi.github.io/li-oauth-delegated-authorization/draft-
   li-oauth-delegated-authorization.html.  Status information for this
   document may be found at https://datatracker.ietf.org/doc/draft-li-
   oauth-delegated-authorization/.

   Discussion of this document takes place on the WG Working Group
   mailing list (mailto:oauth@ietf.org), which is archived at
   https://datatracker.ietf.org/wg/oauth/about/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/oauth/.

   Source for this draft and an issue tracker can be found at
   https://github.com/liuchunchi/li-oauth-delegated-authorization.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on 3 September 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Delegated Party Metadata  . . . . . . . . . . . . . . . . . .   6
     5.1.  Delegated Party Metadata Attributes . . . . . . . . . . .   6
     5.2.  Delegated Party Metadata Example  . . . . . . . . . . . .   7
     5.3.  WWW-Authenticate  . . . . . . . . . . . . . . . . . . . .   8
   6.  Delegation Tokens and Delegated Access Tokens . . . . . . . .   9
     6.1.  Delegation Tokens . . . . . . . . . . . . . . . . . . . .   9
       6.1.1.  Top Level Delegation Token  . . . . . . . . . . . . .  10
     6.2.  Delegated Access Tokens . . . . . . . . . . . . . . . . .  10
   7.  Acquiring Delegation Tokens . . . . . . . . . . . . . . . . .  11
     7.1.  Authorization Code Grant  . . . . . . . . . . . . . . . .  11
     7.2.  Other Grant Types . . . . . . . . . . . . . . . . . . . .  12
   8.  Creating Delegated Access Tokens  . . . . . . . . . . . . . .  12
   9.  Using Delegated Access Tokens . . . . . . . . . . . . . . . .  12
   10. Verification of Delegated Access Tokens . . . . . . . . . . .  13
     10.1.  Local Verification . . . . . . . . . . . . . . . . . . .  13
     10.2.  Token Introspection  . . . . . . . . . . . . . . . . . .  14
   11. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  14
     11.1.  Privacy Benefits . . . . . . . . . . . . . . . . . . . .  14
     11.2.  Relationship to Token Exchange . . . . . . . . . . . . .  14
     11.3.  Trade-offs . . . . . . . . . . . . . . . . . . . . . . .  15
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  15

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   13. Operational Considerations  . . . . . . . . . . . . . . . . .  16
   14. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
     14.1.  Well-Known URIs Registry . . . . . . . . . . . . . . . .  16
     14.2.  OAuth Parameters Registry  . . . . . . . . . . . . . . .  16
     14.3.  OAuth Access Token Types Registry  . . . . . . . . . . .  17
     14.4.  HTTP Field Name Registry . . . . . . . . . . . . . . . .  17
     14.5.  OAuth Delegated Party Metadata Registry  . . . . . . . .  18
       14.5.1.  Registration Template  . . . . . . . . . . . . . . .  18
       14.5.2.  Initial Registry Contents  . . . . . . . . . . . . .  18
   15. References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     15.1.  Normative References . . . . . . . . . . . . . . . . . .  19
     15.2.  Informative References . . . . . . . . . . . . . . . . .  22
   Appendix A.  Token Format . . . . . . . . . . . . . . . . . . . .  22
     A.1.  Example 1 . . . . . . . . . . . . . . . . . . . . . . . .  22
     A.2.  Example 2 . . . . . . . . . . . . . . . . . . . . . . . .  23
   Appendix B.  Integration with Step-Up Authorization . . . . . . .  25
   Appendix C.  Use Cases  . . . . . . . . . . . . . . . . . . . . .  25
     C.1.  Delegating Subset of Access Rights to Specialized AI
           Agents  . . . . . . . . . . . . . . . . . . . . . . . . .  25
     C.2.  Third-Party Analytics Platform Integrated in an Enterprise
           SaaS  . . . . . . . . . . . . . . . . . . . . . . . . . .  26
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   OAuth 2.0 [RFC6749] provides a framework for authorizing third-party
   applications to access protected resources on behalf of a resource
   owner.  However, in existing implementations, access tokens issued to
   clients often contain excessive permissions that exceed actual
   requirements, creating security vulnerabilities and potential data
   exposure risks.

   This specification extends OAuth 2.0 with a delegated authorization
   framework that enables clients to create subordinate access tokens
   with restricted permissions.  This approach addresses the problem of
   over-privileged access tokens by implementing a two-token
   architecture that decouples initial authorization from final resource
   access.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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3.  Terminology

   This specification uses the following terms defined in OAuth 2.0
   [RFC6749]: authorization server, client, resource server, and
   resource owner.

   The following additional terms are used throughout this document:

   *Delegated Party (DP)*:  An entity (e.g., a service, component, or
      application) authorized by the client to access protected
      resources on behalf of the resource owner.

   *Delegated Resource*:  A resource or API endpoint hosted by the
      delegated party that requires access to the resource owner’s
      protected data at a target resource server.

   *Delegation Token*:  A token issued by the authorization server for
      the client that enables the client to create delegated access
      tokens.

   *Delegated Access Token*:  A token created by the client using the
      delegation token, with permissions being a subset of the
      delegation token's privileges and a more limited lifespan.

   *Delegation Key*:  A cryptographic key bound to the delegation token,
      used by the client to sign delegated access tokens.  The
      delegation key is presented in the token request as the
      delegation_key parameter.

4.  Overview

   The delegated authorization framework introduces a hierarchical token
   structure where a client can obtain a delegation token from an
   authorization server and use it to issue subordinate access tokens
   with reduced permissions.  This enables fine-grained access control
   while maintaining the security properties of the original
   authorization grant.

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              +-----------+ 1. Authorization     +---------------+
              |           |      Request         |               |
              |           +---------------------->               |
              |           |                      |   Resource    |
              |           | 2. Authorization     |     Owner     |
              |           |      Grant           |               |
              |           <----------------------+               |
              |           |                      +---------------+
              |  Client   |
              |           | 3. Authorization     +---------------+
              |           |      Grant           |               |
              |           +---------------------->               |
              |           |                      | Authorization |
              |           | 4. Delegation        |     Server    |
              |           |      Token           |               |
              |           <----------------------+               |
              +--^-----+--+                      +---------------+
                 |     |5. Delegated
   6. Delegated  |     |     Access
         Resource|     |     Token
                 |     |
              +--+-----v--+ 5. Delegated         +---------------+
              |           |      Access Token    |               |
              |           +---------------------->               |
              | Delegated |                      |   Resource    |
              |   Party   | 6. Protected         |    Server     |
              |           |      Resource        |               |
              |           <----------------------+               |
              +-----------+                      +---------------+

          Figure 1: Delegated Authorization Framework Architecture

   1.  The client requests authorization from the resource owner.  The
       client indicates in the authorization request that the requested
       authorization grant is for delegated authorization.

   2.  The client receives an authorization grant.

   3.  The client requests a delegation token by authenticating with the
       authorization server and presenting the authorization grant and
       its delegation key as defined in Section 3.

   4.  The authorization server authenticates the client and validates
       the authorization grant, and if valid, issues a delegation token.

   5.  The client calls the delegated party's API, presenting the
       delegated access token generated from the delegation token.  The
       delegated access token is issued by the client using the

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       delegation key.  The delegated party requests the target
       protected resource from the resource server and presents the
       delegated access token.

   6.  The resource server validates the delegated access token, and if
       valid, serves the resource.  The delegated party receives the
       resource, optionally transforms it into a service-specific
       response (also known as delegated resource), and returns it to
       the client.

   Both delegation token and delegated access token can be JSON Web
   Tokens (JWTs) [RFC7519] or CBOR Web Tokens (CWTs) [RFC8392].

5.  Delegated Party Metadata

   Before the OAuth 2.0 client retrieves a delegation token and
   generates a delegated access token for the delegated party, the
   client needs to obtain the authorization server endpoint and the
   permissions needed by the delegated party.  Such information can be
   manually configured into the client, or it can be dynamically
   discovered through delegated party metadata.

   Delegated party metadata enables OAuth 2.0 clients to obtain
   information needed to interact with a delegated party.  The structure
   of the metadata format is similar to "OAuth 2.0 Authorization Server
   Metadata" [RFC8414] and "OAuth 2.0 Protected Resource Metadata"
   [RFC9728].

   The delegated party metadata is retrieved from a well-known [RFC8615]
   location as a JSON [RFC8259] document.  By default, the well-known
   URI string used is /.well-known/oauth-delegated-party.

5.1.  Delegated Party Metadata Attributes

   *resources*:  *RECOMMENDED*. JSON array containing a list of target
      protected resources' resource identifiers, as defined in
      [RFC9728].  Either this attribute or *authorization_servers*
      defined below MUST be present.

   *authorization_servers*:  *OPTIONAL*. JSON array containing a list of
      OAuth authorization server issuer identifiers, as defined in
      [RFC8414].  Either this attribute or *resources* defined above
      MUST be present.

   *permissions_supported*:  *RECOMMENDED*. JSON object indicating the
      permissions the delegated party may request.  The scopes attribute
      lists supported scope values [RFC6749]; the authorization_details
      attribute lists supported rich authorization request objects as

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      defined in [RFC9396].  These guide the client in constructing
      valid authorization and token requests.  Either the scopes
      attribute or the authorization_details attribute must be present.

   *api_permissions*:  *RECOMMENDED*. JSON object mapping API endpoints
      (resource identifiers) to the permissions required to access them.
      Each value can include scopes and/or authorization_details to
      specify the permissions needed for that endpoint/resource.

   *delegated_party_documentation*:  *OPTIONAL*: URL of a page
      containing human-readable information that developers might want
      or need to know when using the delegated party.  The value of this
      field MAY be internationalized.

5.2.  Delegated Party Metadata Example

   The following is a non-normative example delegated party metadata:

   {
     "resources": [
       "https://res1.example.com",
       "https://res2.example.net"
     ],
     "authorization_servers": [
       "https://as1.example.com",
       "https://as2.example.net"
     ],
     "permissions_supported": {
       "scopes": ["profile:read", "profile:write", "email:read", "email:write"],
       "authorization_details": [
         {
           "type": "payment",
           "actions": ["initiate", "status", "cancel"],
           "instructedAmount": {
             "notMoreThan": {
               "currency": "USD",
               "amount": "500.00"
             }
           }
         }
       ]
     },
     "api_permissions": {
       "/emails/list": {
         "scopes": ["email:read"]
       },
       "/balance/transfer": {
         "authorization_details": [

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           {
             "type": "payment",
             "actions": ["initiate"],
             "instructedAmount": {
               "notMoreThan": {
                 "currency": "USD",
                 "amount": "500.00"
               }
             }
           }
         ]
       },
       "/balance/transfer/status": {
         "authorization_details": [
           {
             "type": "payment",
             "actions": ["status"]
           }
         ]
       },
       "/balance/transfer/cancel": {
         "authorization_details": [
           {
             "type": "payment",
             "actions": ["cancel"]
           }
         ]
       }
     },
     "delegated_party_documentation": "https://dp.example.com/dp_documentation.html"
   }

5.3.  WWW-Authenticate

   Upon receipt of a request for a delegated resource that lacks
   credentials, the delegated party can reply with a challenge using the
   401 (Unauthorized) status code ([RFC9110] Section 15.5.2) and the
   WWW-Authenticate header field ([RFC9110] Section 11.6.1).

   This specification introduces a new parameter in the WWW-Authenticate
   HTTP response header field to indicate the delegated party metadata
   URL:

   *delegated_party_metadata*:  The URL of the delegated party metadata.

   The response below is an example of a WWW-Authenticate header that
   includes the delegated party metadata URL.  NOTE: '\' line wrapping
   per [RFC8792].

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   HTTP/1.1 401 Unauthorized
   WWW-Authenticate: Bearer delegated_party_metadata=\
     "https://dp.example.com/.well-known/oauth-delegated-party"

6.  Delegation Tokens and Delegated Access Tokens

   This section defines the properties of delegation tokens and
   delegated access tokens.  The delegated authorization framework uses
   a hierarchical token structure where tokens form a chain: a
   delegation token can be used to create subordinate tokens, which can
   either be another delegation token (to continue the chain) or a
   delegated access token (to access protected resources).  The top-
   level token in the chain is issued by the authorization server, while
   subordinate tokens are created by clients.

6.1.  Delegation Tokens

   A delegation token is a token that can be used to create subordinate
   tokens.  It contains a max_delegation_depth claim that limits the
   maximum length of the delegation chain.

   *delegation_key*:  The cryptographic key bound to the delegation
      token, used by the client to sign subordinate tokens (either
      another delegation token or a delegated access token).  The value
      is a JSON object representing the public key, using key format as
      defined in [RFC7517].  This claim MUST be present in delegation
      tokens.  The corresponding private key is held by the client and
      used to create subordinate tokens.  Subordinate tokens MUST
      include the parent delegation token in the delegation_token claim,
      creating a verifiable chain from the top-level token to the
      subordinate token.

   *max_delegation_depth*:  OPTIONAL.  Integer value indicating the
      maximum depth of the delegation chain.  If not present, the
      delegation chain is unrestricted.  When a client creates a
      subordinate token from a delegation token:

   *  If the parent delegation token has a max_delegation_depth value,
      the subordinate delegation token MUST have a max_delegation_depth
      value smaller than the parent's value.

   *  If the parent delegation token does not have a
      max_delegation_depth value, the subordinate delegation token MAY
      set any max_delegation_depth value.

   When max_delegation_depth reaches 1, the subordinate token MUST be a
   delegated access token (no further delegation is allowed).

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   The scope / authorization_details, aud, exp, and nbf claims MAY be
   present in delegation tokens and can be reduced in subordinate
   tokens.

   *scope* / *authorization_details*:  The scope (as defined in
      [RFC8693]) or authorization details (as defined in [RFC9396]) of
      the delegation token.  When creating a subordinate token, the
      client MAY reduce the scope or authorization_details to a subset
      of the parent token's permissions.

   *aud*:  The audience of the delegation token.  When creating a
      subordinate token, the client MAY narrow the audience to a subset
      of the parent token's audience.

   *exp*:  The expiration time of the delegation token.  When creating a
      subordinate token, the client MUST set an expiration time that is
      no later than the parent token's expiration time.

   *nbf*:  The not-before time of the delegation token.  When creating a
      subordinate token, the client MAY set a not-before time that is
      later than the parent token's not-before time.

6.1.1.  Top Level Delegation Token

   The top-level delegation token is issued by the authorization server
   and MAY contain the iss, sub, and jti claims.  If present, these
   claims apply to the entire token chain.  These claims MUST NOT be
   present in subordinate delegation tokens or delegated access tokens.

   *iss*:  The issuer of the delegation token.  This claim applies to
      all subordinate tokens in the chain.

   *sub*:  The subject of the delegation token, typically representing
      the resource owner or the client.  This claim applies to all
      subordinate tokens in the chain.

   *jti*:  Unique identifier for the delegation token.  This claim
      applies to all subordinate tokens in the chain.

   Subordinate delegation tokens and delegated access tokens MUST NOT
   include the iss, sub, or jti claims.  Verifiers (resource servers and
   delegated parties) SHALL consider these claims from the top-level
   delegation token when validating the entire token chain.

6.2.  Delegated Access Tokens

   A delegated access token is a token used to access protected
   resources.  It cannot be used to create subordinate tokens.

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   The scope, aud, exp, and nbf claims in delegated access tokens follow
   the same rules as in delegation tokens, as described in Section 6.1.

   *max_delegation_depth*:  Delegated access tokens do not need to
      include a max_delegation_depth claim, even if the parent
      delegation token has one.  If a delegated access token includes
      max_delegation_depth, its value MUST be 0.

7.  Acquiring Delegation Tokens

   The client requests a delegation token using standard OAuth 2.0 grant
   types with additional parameters to distinguish delegation requests
   from standard token requests.

7.1.  Authorization Code Grant

   For authorization code grant type, the client MUST include a
   delegation=true parameter in the authorization request to indicate
   that the client is requesting a delegation token instead of an OAuth
   2.0 access token.

   Additionally, the authorization request MUST include either a scope
   parameter (as defined in [RFC6749] Section 3.3), an
   authorization_details parameter (as defined in "Rich Authorization
   Requests" [RFC9396]), or both, that define the permissions granted to
   the requested delegation token.

   In the token request, the client MUST include a delegation_key
   parameter with the value of the delegation key.  The delegation key
   is a public key for digital signature.

   Additionally, the client MAY include in the token request either a
   scope parameter, an authorization_details parameter, or both.  The
   client MAY also include a delegation=true parameter in the token
   request.

   In the token response, the authorization server MUST include an
   access_token attribute whose value is the delegation token, and MUST
   include a token_type attribute valued "Delegation", and MAY include a
   refresh_token attribute which is the refresh token for obtaining a
   new delegation token via the refresh token grant.

   Other procedures of the authorization code grant are as described in
   [RFC6749].  Use of Proof Key for Code Exchange (PKCE) [RFC7636] is
   RECOMMENDED.

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7.2.  Other Grant Types

   Other OAuth 2.0 grant types, such as the refresh token grant or
   client credentials grant, MAY support delegated authorization by
   including the delegation and delegation_key parameters when
   applicable.  The authorization server MUST validate that the client
   is authorized to request delegation tokens using the given grant
   type.

8.  Creating Delegated Access Tokens

   The client creates delegated access tokens by:

   1.  Validating the delegation token's validity and permissions.

   2.  Generating a subordinate access token with (optionally) reduced
       privileges.

   3.  Applying cryptographic protection using the delegation key
       (digital signature).

   The client MUST include the delegation token in the delegation_token
   attribute of the delegated access token.

   The client MUST ensure that the delegated access token's scope,
   lifetime, audience, and other claims do not exceed those of the
   delegation token.  The client MAY generate single-use delegated
   access tokens that the resource server or authorization server only
   consider valid when validating it for the first time.

   The client is RECOMMENDED to "sender-constrain" the delegated access
   tokens by binding the delegated access tokens with public keys or
   certificates where the corresponding private keys are owned by the
   delegated parties, via techniques similar to OAuth 2.0 mTLS [RFC8705]
   or OAuth 2.0 DPoP [RFC9449].

9.  Using Delegated Access Tokens

   When the client accesses a delegated resource on the delegated party,
   the client MUST include the delegated access token as a bearer token
   [RFC6750] in the Delegated-Authorization header, used by the target
   resource server to verify requests from the delegated party.  The
   Delegated-Authorization header MAY be used in combination with an
   Authorization header used by the delegated party to verify the
   request from the client.

   For example:

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   GET /dp-resource HTTP/1.1
   Host: delegated-party.example.com
   Authorization: Bearer mF_9.B5g1234
   Delegated-Authorization: Bearer mF_9.B5f-4.1JqM

   Upon receiving a delegated resource request with a Delegated-
   Authorization header, the delegated party sends a request to the
   target resource server for the respective target resource.  The
   delegated party MUST include the received delegated access token as a
   bearer token in the Authorization header.

   For example:

   GET /target-resource HTTP/1.1
   Host: resource.example.com
   Authorization: Bearer mF_9.B5f-4.1JqM

10.  Verification of Delegated Access Tokens

   Resource servers verify delegated access tokens through either local
   validation using pre-configured public keys or remote validation via
   token introspection [RFC7662] at the authorization server.

10.1.  Local Verification

   The resource server verifies delegated access tokens by:

   1.  The resource server is pre-configured with the authorization
       server's public key, or it fetches the public key via the
       authorization server's JWKS endpoint [RFC7517].

   2.  Checking the digital signature of the delegation token (part of
       the delegated access token) against the authorization server's
       public key.

   3.  Checking the digital signature of the delegated access token
       against the delegation key bound to the delegation token.

   4.  Verifying the delegated access token's permissions and validity
       are within the scope of the delegation token.

   5.  Verifying the delegated access token is within validity period,
       and the delegated access token's permissions cover the resource
       request.

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10.2.  Token Introspection

   The resource server sends the delegated access token to the
   authorization server via the token introspection endpoint [RFC7662].
   The authorization server verifies the delegated access token against
   its keys.

11.  Privacy Considerations

   This section describes the privacy properties of the local delegation
   approach defined in this specification.

11.1.  Privacy Benefits

   When a client creates delegated access tokens locally using a
   delegation token, the authorization server only observes the initial
   delegation token request.  After that, the client can independently
   issue subordinate tokens without further authorization server
   interaction.  This provides the following privacy benefits:

   *  *Minimized Authorization Server Visibility*: The authorization
      server does not learn which delegated parties are authorized, what
      resources they access, or when they access them.

   *  *No Access Pattern Correlation*: The authorization server cannot
      track usage patterns or correlate activities across different
      delegated parties.

   *  *Reduced Data Collection*: The authorization server stores only
      metadata about the initial delegation token, not about each
      delegated access token.

   *  *Network Traffic Reduction*: Fewer network round-trips to the
      authorization server reduce exposure to network surveillance.

11.2.  Relationship to Token Exchange

   Token Exchange [RFC8693] provides a mechanism for delegating access
   by having the client exchange one token for another at the
   authorization server.  That approach requires authorization server
   involvement for each delegation event, which necessarily exposes
   delegation metadata to the authorization server.  The local
   delegation approach in this specification performs delegation
   entirely on the client side after the initial token issuance,
   providing an alternative with different privacy characteristics.

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11.3.  Trade-offs

   While local delegation provides significant privacy benefits,
   implementations should consider:

   *  *Client Responsibility*: The client must securely protect the
      delegation key and properly enforce delegation rules.

   *  *Auditability*: Deployments requiring delegation event audits can
      implement client-side logging rather than relying on authorization
      server monitoring.

   *  *Revocation*: If a delegation key is compromised, the
      authorization server may need to revoke the entire delegation
      token.

12.  Security Considerations

   This specification extends OAuth 2.0 to support delegated
   authorization through hierarchical token issuance.  While this
   enables fine-grained privilege delegation, it also introduces new
   trust and security considerations.

   *  Delegation tokens MUST NOT be sent to resource servers without
      subordinate delegated access tokens.  Resource servers and
      authorization servers MUST NOT treat delegation tokens as regular
      OAuth access tokens.

   *  Clients MUST protect the delegation key, as compromise allows an
      attacker to mint valid delegated access tokens within the scope of
      the delegation token.

   *  Delegated access tokens SHOULD have short lifetimes and be bound
      to specific audiences, methods, and sender keys (e.g., via DPoP or
      mTLS) to mitigate replay and token leakage risks.  Resource
      servers MUST validate both the delegation token and the delegated
      access token, ensuring the latter does not exceed the former’s
      permissions.

   *  Token introspection CAN be used in scenarios where the tokens are
      kept opaque from the delegated party and the resource server.  If
      employed, token introspection responses MUST NOT reveal sensitive
      internal information.  Authorization servers SHOULD enforce rate
      limiting and audit token issuance and validation activities.

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13.  Operational Considerations

   Deployments of this specification should consider the following
   operational aspects:

   *  *Key Management*: Clients MUST securely store and rotate
      delegation keys.  Authorization servers SHOULD support key
      rotation for delegation tokens and provide mechanisms to revoke
      compromised keys.

   *  *Token Lifetimes*: Delegation tokens SHOULD have longer lifetimes
      than delegated access tokens to reduce authorization server load,
      and SHOULD be refreshable using refresh tokens.

   *  *Metadata Caching*: Delegated party metadata at the well-known URI
      /.well-known/oauth-delegated-party can be cached by clients; a
      reasonable default TTL (e.g., 24 hours) is RECOMMENDED.

   *  *Error Handling*: Delegated parties and resource servers SHOULD
      provide clear error responses (e.g., invalid token, insufficient
      scope) without exposing implementation details.

   *  *Interoperability*: Implementers SHOULD ensure compatibility with
      existing OAuth 2.0 features such as PKCE, Rich Authorization
      Requests, and sender-constrained tokens.

14.  IANA Considerations

14.1.  Well-Known URIs Registry

   This specification registers the following entry in the "Well-Known
   URIs" registry:

   *  *URI suffix*: oauth-delegated-party

   *  *Reference*: [this document]

   *  *Status*: permanent

   *  *Change controller*: IETF

   *  *Related information*: (none)

14.2.  OAuth Parameters Registry

   This specification registers the following parameters in the "OAuth
   Parameters" registry:

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   *Delegation:*

   *  *Name*: delegation

   *  *Parameter Usage Location*: authorization request, token request

   *  *Change Controller*: IETF

   *  *Reference*: [this document]

   *Delegation Key:*

   *  *Name*: delegation_key

   *  *Parameter Usage Location*: token request

   *  *Change Controller*: IETF

   *  *Reference*: [this document]

14.3.  OAuth Access Token Types Registry

   This specification registers the following parameters in the "OAuth
   Access Token Types" registry:

   *  *Name*: Delegation

   *  *Additional Token Endpoint Response Parameters*: (none)

   *  *HTTP Authentication Scheme(s)*: Bearer

   *  *Change Controller*: IETF

   *  *Reference*: [this document]

14.4.  HTTP Field Name Registry

   This specification registers the following parameters in the
   "Hypertext Transfer Protocol (HTTP) Field Name" registry:

   *  *Field Name*: Delegated-Authorization

   *  *Status*: permanent

   *  *Structured Type*: (none)

   *  *Reference*: [this document]

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14.5.  OAuth Delegated Party Metadata Registry

   This specification establishes the "OAuth Delegated Party Metadata"
   registry for OAuth 2.0 delegated party metadata names.  The registry
   records the delegated party metadata parameter and a reference to the
   specification that defines it.

14.5.1.  Registration Template

   *Metadata Name*:  The name requested (e.g., "resource").  This name
      is case sensitive.  Names may not match other registered names in
      a case-insensitive manner unless the designated experts state that
      there is a compelling reason to allow an exception.

   *Metadata Description*:  Brief description of the metadata (e.g.,
      "Resource identifier URL").

   *Change Controller*:  For IETF Stream RFCs, list "IETF".  For others,
      give the name of the responsible party.  Other details (e.g.,
      postal address, email address, home page URI) may also be
      included.

   *Specification Document(s)*:  Reference to the document or documents
      that specify the parameter, preferably including URIs that can be
      used to retrieve copies of the documents.  An indication of the
      relevant sections may also be included but is not required.

14.5.2.  Initial Registry Contents

   *Resources:*

   *  *Metadata Name*: resources

   *  *Metadata Description*: JSON array containing a list of target
      protected resources' resource identifier URLs

   *  *Change Controller*: IETF

   *  *Specification Document(s)*: [this document]

   *Authorization Servers:*

   *  *Metadata Name*: authorization_servers

   *  *Metadata Description*: JSON array containing a list of
      authorization server issuer identifiers

   *  *Change Controller*: IETF

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   *  *Specification Document(s)*: [this document]

   *Supported Permissions:*

   *  *Metadata Name*: permissions_supported

   *  *Metadata Description*: JSON object indicating the permissions the
      delegated party may request

   *  *Change Controller*: IETF

   *  *Specification Document(s)*: [this document]

   *API Permissions:*

   *  *Metadata Name*: api_permissions

   *  *Metadata Description*: JSON object mapping API endpoints
      (resource identifiers) to the permissions required to access them

   *  *Change Controller*: IETF

   *  *Specification Document(s)*: [this document]

   *Delegated Party Documentation:*

   *  *Metadata Name*: delegated_party_documentation

   *  *Metadata Description*: URL of a page containing human-readable
      information that developers might want or need to know when using
      the delegated party

   *  *Change Controller*: IETF

   *  *Specification Document(s)*: [this document]

15.  References

15.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/rfc/rfc6749>.

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   [RFC6750]  Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
              Framework: Bearer Token Usage", RFC 6750,
              DOI 10.17487/RFC6750, October 2012,
              <https://www.rfc-editor.org/rfc/rfc6750>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/rfc/rfc7515>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <https://www.rfc-editor.org/rfc/rfc7516>.

   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,
              <https://www.rfc-editor.org/rfc/rfc7517>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/rfc/rfc7519>.

   [RFC7636]  Sakimura, N., Ed., Bradley, J., and N. Agarwal, "Proof Key
              for Code Exchange by OAuth Public Clients", RFC 7636,
              DOI 10.17487/RFC7636, September 2015,
              <https://www.rfc-editor.org/rfc/rfc7636>.

   [RFC7662]  Richer, J., Ed., "OAuth 2.0 Token Introspection",
              RFC 7662, DOI 10.17487/RFC7662, October 2015,
              <https://www.rfc-editor.org/rfc/rfc7662>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/rfc/rfc8259>.

   [RFC8392]  Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
              "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
              May 2018, <https://www.rfc-editor.org/rfc/rfc8392>.

   [RFC8414]  Jones, M., Sakimura, N., and J. Bradley, "OAuth 2.0
              Authorization Server Metadata", RFC 8414,
              DOI 10.17487/RFC8414, June 2018,
              <https://www.rfc-editor.org/rfc/rfc8414>.

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   [RFC8615]  Nottingham, M., "Well-Known Uniform Resource Identifiers
              (URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
              <https://www.rfc-editor.org/rfc/rfc8615>.

   [RFC8693]  Jones, M., Nadalin, A., Campbell, B., Ed., Bradley, J.,
              and C. Mortimore, "OAuth 2.0 Token Exchange", RFC 8693,
              DOI 10.17487/RFC8693, January 2020,
              <https://www.rfc-editor.org/rfc/rfc8693>.

   [RFC8705]  Campbell, B., Bradley, J., Sakimura, N., and T.
              Lodderstedt, "OAuth 2.0 Mutual-TLS Client Authentication
              and Certificate-Bound Access Tokens", RFC 8705,
              DOI 10.17487/RFC8705, February 2020,
              <https://www.rfc-editor.org/rfc/rfc8705>.

   [RFC9110]  Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/rfc/rfc9110>.

   [RFC9396]  Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0
              Rich Authorization Requests", RFC 9396,
              DOI 10.17487/RFC9396, May 2023,
              <https://www.rfc-editor.org/rfc/rfc9396>.

   [RFC9449]  Fett, D., Campbell, B., Bradley, J., Lodderstedt, T.,
              Jones, M., and D. Waite, "OAuth 2.0 Demonstrating Proof of
              Possession (DPoP)", RFC 9449, DOI 10.17487/RFC9449,
              September 2023, <https://www.rfc-editor.org/rfc/rfc9449>.

   [RFC9700]  Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
              "Best Current Practice for OAuth 2.0 Security", BCP 240,
              RFC 9700, DOI 10.17487/RFC9700, January 2025,
              <https://www.rfc-editor.org/rfc/rfc9700>.

   [RFC9728]  Jones, M.B., Hunt, P., and A. Parecki, "OAuth 2.0
              Protected Resource Metadata", RFC 9728,
              DOI 10.17487/RFC9728, April 2025,
              <https://www.rfc-editor.org/rfc/rfc9728>.

   [I-D.lombardo-oauth-step-up-authz-challenge-proto]
              Lombardo, J., Babeanu, A., Zehavi, Y., and G. Fletcher,
              "OAuth 2.0 step-up authorization challenge proto", Work in
              Progress, Internet-Draft, draft-lombardo-oauth-step-up-
              authz-challenge-proto-02, 30 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-lombardo-
              oauth-step-up-authz-challenge-proto-02>.

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15.2.  Informative References

   [RFC8792]  Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
              "Handling Long Lines in Content of Internet-Drafts and
              RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
              <https://www.rfc-editor.org/rfc/rfc8792>.

Appendix A.  Token Format

   The example tokens in this section are shown in Flattened JSON
   Serialization [RFC7515] [RFC7516], un-base64url-encoded and with
   comments for ease of reading.  When used as JWTs [RFC7519], they
   should be represented in Compact Serialization [RFC7515] [RFC7516].
   Similarly, they can be represented as CWTs [RFC8392].

A.1.  Example 1

   In this example, the delegation token is a JWS token signed with
   HS256, and the delegated access token is a JWS token signed with
   RS256.

   *Delegation Token*:

   {
     "protected": {
       "_comment": "to be base64url-encoded",
       "alg": "HS256",
       "typ": "JWT",
       "kid": "as-key-1"
     },
     "payload": {
       "_comment": "to be base64url-encoded",
       "iss": "https://as1.example.com",
       "sub": "user@example.com",
       "aud": "https://res1.example.com",
       "iat": 1772177588,
       "exp": 1774769588,
       "scope": "email:read email:send",
       "delegation_key": {
         "kty": "RSA",
         "n": "0Z5t3Rwhfz4MJxdNzg2I6Bsf9H_3kcMKtH6iwJsLV2DKO1MVcHb6wsxHZpqRePjm5Q1-pImr4pT67hCHyAR6kS4QbTrBZcjSe8lsvZIiifiBVWZxz8ZAfdj6EFSOWhFLZ0GVqe9NMslwX1hHOwmhRmMjGjexISPsZk5qN3gwqmD36H1GS-rE-cWlXI9f4pVcCdYqE0rfhZ7hDn5mrpWWY8wJuQa2jFqX-Fhyvt_Zh-qaa5Wp8cLJPS_ceAcLeS5mOYE58beelp51PuCDpq7a9fN4K_EpcSD7Ay0GrJxgN_VcLA7DgOAuU6zYDzk2KnmQ3qz35Tj5hy8jDHgF1AaSTw",
         "e": "AQAB"
       }
     },
     "signature": "SBwdWhy4dissabBRoyyxMxRuVUbsFYv_1HZFeROLh5A"
   }

   *Delegated Access Token*:

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   {
     "protected": {
       "_comment": "to be base64url-encoded",
       "alg": "RS256",
       "typ": "JWT",
       "kid": "delegation-key-1"
     },
     "payload": {
       "_comment": "to be base64url-encoded",
       "sub": "https://dp1.example.com",
       "aud": "https://res1.example.com",
       "iat": 1772181188,
       "exp": 1772184788,
       "scope": "email:read",
       "delegationToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImFzLWtleS0xIn0.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.SBwdWhy4dissabBRoyyxMxRuVUbsFYv_1HZFeROLh5A"
     },
     "signature": "df5sTdp6j-ULv3To3yqYFFZWLrY41wu6jpKfsZdjMNMeRH3TXY5nSc-lhdFfJElVGnyCa5Rf9YGlvacGVy84maFCq0zhNTiLL8xBYieCKTAhmMuWZvIUZFBoE1KBj2YXskpnU6CFTKhALbW5lidZSGXdcEnygxwaumpO_AxlYghU8RQrQgF1wAsoDLcoun1-FROuHUzqKGWqYSbXe1lGJ3dTt5ftod7SjGqM2Quz4BvfQMpw82VVGq7YlvRJMuPe4ITUeikFNQ672bvVrjhwHUlglQ9HuFj5iroHqwr6dLtfKVDBtw33A_lCnsWfk4vPWDJ-1fy3Klj4hT_bhBIVJA"
   }

A.2.  Example 2

   In this example, the delegation token chain consists of three tokens:
   a top-level delegation token issued by the authorization server, a
   subordinate delegation token created by the client, and a delegated
   access token created from the subordinate token.  The top-level
   delegation token has max_delegation_depth of 3, which allows for two
   levels of delegation.

   *Top-Level Delegation Token*:

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   {
     "protected": {
       "_comment": "to be base64url-encoded",
       "alg": "RS256",
       "typ": "JWT",
       "kid": "as-key-2"
     },
     "payload": {
       "_comment": "to be base64url-encoded",
       "iss": "https://as1.example.com",
       "sub": "user@example.com",
       "aud": "https://res1.example.com",
       "iat": 1772177588,
       "exp": 1774769588,
       "scope": "email:read email:write email:send",
       "delegation_key": {
         "kty": "RSA",
         "n": "3O1EVa-_zsENOhylq99puKjF6NBq8S8Ntw9sufyCB9LrTSs-xRoDQ7X6rYbPEOn5E-6ASZyUW2vFxLacj0Wir05hznlnfRLRTmJhud4im5COfAhuiPeL0Mbs3WFLdBfWVGXSP2O5UNkd7dJ2KqudqxNF81Nrt51RpmPR59pUZS3REfAYgtqhQ07WuCTzd2VpFttPFurDSiWcriyELNdgsT9wap0nyceSVLQgY9ZgR0VvsmHj_LUKie1t5RCjTsaMHJH6x3QI0tjKG9Psbil0ORlhA9WEgOO6E6KOC_StEBnK_Ntb2ArGPDjlNPzTqWOeeev84MM8VXdRzpTLOrRmHQ",
         "e": "AQAB"
       },
       "max_delegation_depth": 3
     },
     "signature": "p1OjJQ2tASuFPPCXzdbuSHaZiPTF2jM1Z_My2_qPx0IAAJJ5RVo9Km2hFeXjqqGcjkG5wEFxMw_q8JO48O9bVaKNBa1k_-UoBxf5KlMpldMFIUyV4D8Sugshh73iqVii5HW2MY4uS5Gj46GDUcX1NQRg8LW6Wa4zso0SPfIfunXF0dvBG24cCUoIFOr1NzryZ7OcVt9kdC4_uXGoSmjtGl1XsRvgb216fZFuZV0F88zWFsDcBZn4i8qGcBS2XAHjW4jbH7Y1O8dvl2h0afftmNkG2ZgHPl3phj_i-unQsAxhCUI_8MjtfF5iwe586uQw_1iED2IUlEXOgX-Ld5GgTw"
   }

   *Subordinate Delegation Token*:

   {
     "protected": {
       "_comment": "to be base64url-encoded",
       "alg": "RS256",
       "typ": "JWT",
       "kid": "delegation-key-2"
     },
     "payload": {
       "_comment": "to be base64url-encoded",
       "aud": "https://res1.example.com",
       "iat": 1772181188,
       "exp": 1772782388,
       "max_delegation_depth": 1,
       "scope": "email:read email:write",
       "delegationToken": "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImFzLWtleS0yIn0.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.p1OjJQ2tASuFPPCXzdbuSHaZiPTF2jM1Z_My2_qPx0IAAJJ5RVo9Km2hFeXjqqGcjkG5wEFxMw_q8JO48O9bVaKNBa1k_-UoBxf5KlMpldMFIUyV4D8Sugshh73iqVii5HW2MY4uS5Gj46GDUcX1NQRg8LW6Wa4zso0SPfIfunXF0dvBG24cCUoIFOr1NzryZ7OcVt9kdC4_uXGoSmjtGl1XsRvgb216fZFuZV0F88zWFsDcBZn4i8qGcBS2XAHjW4jbH7Y1O8dvl2h0afftmNkG2ZgHPl3phj_i-unQsAxhCUI_8MjtfF5iwe586uQw_1iED2IUlEXOgX-Ld5GgTw"
     },
     "signature": "lnf8Wz5M_B4dVTOOjT0aQa0ZSqEbTZVGb1HU_dk1tJ4eCbkCB8lmO0wJXc07Ys8gKqqb3TS4tKUbnwwKo3_Dw3FGYjbDqDE7rBtdc0lqi6fKSecff2ujVCi2U2dLjX78_h7U0LP1XbJuhkjdBYa-_mwiygAXf0j8cilXTigbTWJfgqcziVmkJzl9a_5HJ8HYF5ohdGmVBhOfyRrwGikYoHEQB6Ye_6jwTD_IQsUJe0eYdD4xAdA7C2awZAvhdYduKXit7WSyGuEhbyKopsm6WVZz4BkjWDjcJ2S7Xjb6RxPCGc_nNiAMsGT1nG9MIj-oGYy8gIWPSLEyF_6sk8hiaQ"
   }

   *Delegated Access Token*:

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   {
     "protected": {
       "_comment": "to be base64url-encoded",
       "alg": "RS256",
       "typ": "JWT",
       "kid": "delegation-key-2-sub"
     },
     "payload": {
       "_comment": "to be base64url-encoded",
       "sub": "https://dp1.example.com",
       "aud": "https://res1.example.com",
       "iat": 1772184788,
       "exp": 1772188388,
       "scope": "email:read",
       "delegationToken": "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImRlbGVnYXRpb24ta2V5LTIifQ.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.lnf8Wz5M_B4dVTOOjT0aQa0ZSqEbTZVGb1HU_dk1tJ4eCbkCB8lmO0wJXc07Ys8gKqqb3TS4tKUbnwwKo3_Dw3FGYjbDqDE7rBtdc0lqi6fKSecff2ujVCi2U2dLjX78_h7U0LP1XbJuhkjdBYa-_mwiygAXf0j8cilXTigbTWJfgqcziVmkJzl9a_5HJ8HYF5ohdGmVBhOfyRrwGikYoHEQB6Ye_6jwTD_IQsUJe0eYdD4xAdA7C2awZAvhdYduKXit7WSyGuEhbyKopsm6WVZz4BkjWDjcJ2S7Xjb6RxPCGc_nNiAMsGT1nG9MIj-oGYy8gIWPSLEyF_6sk8hiaQ"
     },
     "signature": "mn-0y0F3lx0IM-60UsBp1_M7uRhdT28dPqxt6-s1OnjM-obyF-p5XbQV9jI5Q56X4cb3jLl6RkM789ODTGt5y4QNdOA2WhlS0WldSOzYkV1Xj2yrC0mZakYCHTpzzgvfeUjeNj-fDWmtgRb2Lfm6Z6dguT071WQkaIyH4IW5xVxroqbn1tFM07uX3huIV9tC_iS926rWaDW7eQDm1nhhjS_QSgUcTF1eJy7hOjEtzs70iij5bQU-B9nn6OfXdpb1jO5vx3lCSnZfL2h2EaQYK3CbjrflbDnIYKtJ0NMx5D03KRcv_uPlG5HHRL5cuMz8eToKc08rc0Qs5PxDbeqV4A"
   }

Appendix B.  Integration with Step-Up Authorization

   This specification can be used together with step-up authorization
   [I-D.lombardo-oauth-step-up-authz-challenge-proto].  When a resource
   server returns an insufficient_authorization error, the client can
   create a new delegated access token with the required permissions
   from its existing delegation token.

   This is particularly useful for AI agents that hold a delegation
   token.  Upon receiving a step-up authorization challenge, the agent
   can automatically create a new delegated access token with the
   additional authorization_details required by the resource server,
   without requiring the user to re-authenticate.

   Resource servers that support both delegated authorization and step-
   up challenges SHOULD use the body_instructions parameter to specify
   the exact authorization_details or scope required.

Appendix C.  Use Cases

C.1.  Delegating Subset of Access Rights to Specialized AI Agents

   Enterprise Identity and Access Management systems often employ Role
   Based Access Control (RBAC) or Attribute Based Access Control (ABAC),
   assigning a set of minimal permissions to the employee based on their
   role, department, or other attributes.  AI Agent can be an employee's
   personal assistant, or a virtual employee of a certain department in
   general.  The permissions delegated to an AI agent CAN be long-term,
   but an AI agent MUST NOT directly inherit all its owner's access

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   rights.  Rather, they SHOULD be a subset of its owner, bound to
   specific service/API/database/codebase according to its specialty and
   dedicated workflow.

     +==================+===========================================+
     | Role             | Service / Component                       |
     +==================+===========================================+
     | Resource Owner   | an enterprise, individual or a department |
     +------------------+-------------------------------------------+
     | Client           | agent's client application                |
     +------------------+-------------------------------------------+
     | Delegated Party  | CI-CD agent, test agent, DEV agent,       |
     |                  | research agent                            |
     +------------------+-------------------------------------------+
     | Authorization    | enterprise IAM system                     |
     | Server           |                                           |
     +------------------+-------------------------------------------+
     | Resource Server  | enterprise IT systems                     |
     +------------------+-------------------------------------------+
     | Target Protected | DEV/STAGE/PROD environments, internal     |
     | Resource         | knowledge database                        |
     +------------------+-------------------------------------------+

                            Table 1: AI Agents

C.2.  Third-Party Analytics Platform Integrated in an Enterprise SaaS

   In this scenario, a corporate customer uses a Software-as-a-Service
   (SaaS) Customer Relationship Management (CRM) application.  The
   customer wishes to gain business insights by granting a specialized
   third-party analytics platform limited access to its CRM data.

   The CRM application obtains a delegation token from the enterprise's
   identity provider.  It then creates a narrowly scoped delegated
   access token for the analytics service.  This token only permits read
   access to a predefined, non-sensitive subset of customer data (e.g.,
   names and identifiers, but not personal email addresses).  The
   analytics platform uses this token to pull data, generates an
   aggregated business intelligence report, and delivers it back to the
   CRM application for the corporate customer to view.

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   +===========================+======================================+
   | Role                      | Service / Component                  |
   +===========================+======================================+
   | Resource Owner            | company A (the tenant)               |
   +---------------------------+--------------------------------------+
   | Client                    | SaaS CRM application                 |
   +---------------------------+--------------------------------------+
   | Delegated Party           | analytics service                    |
   +---------------------------+--------------------------------------+
   | Authorization Server      | enterprise IdP                       |
   +---------------------------+--------------------------------------+
   | Resource Server           | CRM application server               |
   +---------------------------+--------------------------------------+
   | Target Protected Resource | CRM application's data retrieval API |
   +---------------------------+--------------------------------------+

                         Table 2: Enterprise-SaaS

Authors' Addresses

   Ruochen Li
   Huawei Int. Pte Ltd
   Email: li.ruochen@h-partners.com

   Haiguang Wang
   Huawei Int. Pte Ltd
   Email: wang.haiguang.shieldlab@huawei.com

   Chunchi Peter Liu
   Huawei Technologies
   Email: liuchunchi@huawei.com

   Tieyan Li
   Huawei Int. Pte Ltd
   Email: Li.Tieyan@huawei.com

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