



Network Working Group                                            A. RAUT
Internet-Draft                                               12 May 2026
Intended status: Informational                                          
Expires: 13 November 2026


                     Transaction Tokens For Agents
           draft-araut-oauth-transaction-tokens-for-agents-01

Abstract

   This document specifies an extension to the OAUTH-TXN-TOKENS
   (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-oauth-
   transaction-tokens.html) to support agent context propagation within
   Transaction Tokens for agent-based workloads.  The extension defines
   the use of the act field to identify the agent performing the action,
   and leverages the existing sub field (as defined in the base
   Transaction Tokens specification) to represent the principal.  The
   sub field is populated according to the rules specified in OAUTH-TXN-
   TOKENS (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
   oauth-transaction-tokens.html), based on the 'subject_token' provided
   in the token request.  For autonomous agents operating independently,
   the sub field represents the agent itself.  These mechanisms enable
   services within the call graph to make more granular access control
   decisions, thereby enhancing security.

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://ashayraut.github.io/oauth-transactiontokens-for-agents/draft-
   oauth-transaction-tokens-for-agents.html.  Status information for
   this document may be found at https://datatracker.ietf.org/doc/draft-
   araut-oauth-transaction-tokens-for-agents/.

   Source for this draft and an issue tracker can be found at
   https://github.com/ashayraut/oauth-transactiontokens-for-agents.

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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions and Terminology . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Protocol overview . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Transaction Flow  . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Agent Application Transaction Flows . . . . . . . . . . .   5
       3.2.1.  Principal-Initiated Flow  . . . . . . . . . . . . . .   5
       3.2.2.  Autonomous Flow . . . . . . . . . . . . . . . . . . .   6
     3.3.  Flow Diagrams . . . . . . . . . . . . . . . . . . . . . .   7
       3.3.1.  Principal-Initiated Flow  . . . . . . . . . . . . . .   7
       3.3.2.  Autonomous Flow . . . . . . . . . . . . . . . . . . .   8
     3.4.  Replacement tokens  . . . . . . . . . . . . . . . . . . .   9
     3.5.  Txn-Token Format  . . . . . . . . . . . . . . . . . . . .  10
       3.5.1.  JWT Header  . . . . . . . . . . . . . . . . . . . . .  10
       3.5.2.  JWT Body Claims . . . . . . . . . . . . . . . . . . .  10
     3.6.  Agentic Context . . . . . . . . . . . . . . . . . . . . .  11
       3.6.1.  Field definitions and population  . . . . . . . . . .  11
       3.6.2.  Example of agentic_ctx with additional context  . . .  12
       3.6.3.  Implementation Note: Integrity and Resolution . . . .  13
   4.  Multi-agent flows . . . . . . . . . . . . . . . . . . . . . .  13
     4.1.  The Bifurcated Trust Model  . . . . . . . . . . . . . . .  13
     4.2.  Monotonic Attenuation of Trust  . . . . . . . . . . . . .  14
       4.2.1.  Delegation via Replacement Flow . . . . . . . . . . .  14
       4.2.2.  Multi-agent example JWT body claims . . . . . . . . .  14
       4.2.3.  Loop prevention . . . . . . . . . . . . . . . . . . .  15



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   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  19
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  19
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  20
   Appendix B.  Contributors . . . . . . . . . . . . . . . . . . . .  20
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   Traditional zero trust authorization systems face new challenges when
   applied to AI agent workloads.  Unlike conventional web services, AI
   agents possess capabilities for autonomous operation, behavioral
   adaptation, and dynamic integration with various data sources.  These
   characteristics may lead to decisions that extend beyond their
   initial operational boundaries.

   Existing zero trust models, which effectively manage permissions and
   access scopes for traditional web services, require enhancement to
   address the unique properties of AI agents.  Authorization systems
   must evaluate each AI agent interaction independently, considering
   both the immediate context and intended action.  This necessitates
   more sophisticated approaches to policy enforcement, behavioral
   monitoring, and audit tracking to maintain security governance.

   Transaction Tokens (Txn-Tokens) are short-lived, signed JSON Web
   Tokens RFC7519 (https://tools.ietf.org/html/rfc7519) that convey
   identity and authorization context.  However, the current Txn-Token
   format lacks sufficient context for services within the call chain to
   implement fine-grained access control policies for agent-based
   workflows.  Specifically, it does not provide adequate information
   about the AI agent's identity or its initiating entity, limiting
   transaction traceability.  With this extension, Transaction Tokens
   will carry agent identity information which will help in better
   traceability for AI Agent's actions deep down the web service graph
   connecting multiple web services involved in completing a transaction
   in distributed systems.

   This document defines three new contexts within the Transaction Token
   to address these limitations:

   1.  The act claim, which identifies the AI agent performing the
       action, aligning with OAuth 2.0 Token Exchange RFC8693
       (https://tools.ietf.org/html/rfc8693) terminology for actor
       tokens

   2.  The sub claim, as defined in OAUTH-TXN-TOKENS
       (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
       oauth-transaction-tokens.html), which represents the principal on



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       whose behalf the transaction is being performed.  The population
       of this field follows the rules specified in the base Transaction
       Tokens specification, based on the 'subject_token' provided in
       the token request.

   3.  An optional agentic_ctx claim.  The value of this claim, if
       present, MUST be a JSON object.  The agentic_ctx claim conveys
       attributes about the agent and its operational constraints that
       are relevant to authorization, auditing, and policy evaluation.

   This extension leverages the existing Txn-Token infrastructure to
   enable secure propagation of AI agent context throughout the service
   graph.

1.1.  Conventions and Terminology

   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 (https://datatracker.ietf.org/doc/html/rfc2119) RFC8174
   (https://datatracker.ietf.org/doc/html/rfc8174) when, and only when,
   they appear in all capitals, as shown here.

2.  Terminology

   Agentic-AI: AI Agentic applications are software applications that
   utilize Large Language Models (LLM)s and plans, reasons,and takes
   actions independently to achieve complex, multi-step goals with
   minimal human oversight.

   Workload: An independent computational unit that can autonomously
   receive and process invocations, and can generate invocations of
   other workloads.  Examples of workloads include containerized
   microservices, monolithic services and infrastructure services such
   as managed databases.

   Trust Domain: A collection of systems, applications, or workloads
   that share a common security policy.  In practice this may include a
   virtually or physically separated network, which contains two or more
   workloads.  The workloads within a Trust Domain may be invoked only
   through published interfaces.

   Call Chain: A sequence of synchronous invocations that results from
   the invocation of an external endpoint.

   External Endpoint: A published interface to a Trust Domain that
   results in the invocation of a workload within the Trust Domain.
   This is the first service in the call chain where request starts.



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   Transaction Token (Txn-Token): A signed JWT with a short lifetime,
   providing immutable information about the user or workload, certain
   parameters of the call, and specific contextual attributes of the
   call.  The Txn-Token is used to authorize subsequent calls in the
   call chain.

   Transaction Token Service (Txn-Token Service): A special service
   within the Trust Domain that issues Txn-Tokens to requesting
   workloads.  Each Trust Domain using Txn-Tokens MUST have exactly one
   logical Txn-Token Service.

3.  Protocol overview

3.1.  Transaction Flow

   This section describes the process by which an agent application
   obtains a Transaction Token, either acting autonomously or on behalf
   of a principal.  The external endpoint requests a Txn-Token following
   the procedures defined in OAUTH-TXN-TOKENS (https://drafts.oauth.net/
   oauth-transaction-tokens/draft-ietf-oauth-transaction-tokens.html),
   augmented with additional context for agent identity and, when
   applicable, principal identity.

3.2.  Agent Application Transaction Flows

   The Transaction Token creation process varies depending on the
   presence of a principal.

3.2.1.  Principal-Initiated Flow

   When a principal initiates the workflow, the following steps occur:

   1.  The principal invokes the agent application to perform a task.

   2.  The agent application calls an external endpoint.  External
       endpoint throws back OAuth challenges.

   3.  The agent application authenticates using an OAuth 2.0 Auth code
       flow RFC6749 (https://tools.ietf.org/html/rfc6749) access token.
       The access token contains subject and clientId claims as per
       RFC9068 (https://datatracker.ietf.org/doc/rfc9068).

   4.  The external endpoint submits the received access token along
       with its Subject token to the Txn-Token Service.  Subject token
       requirements are specified in OAUTH-TXN-TOKENS
       (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
       oauth-transaction-tokens.html).




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   5.  The Txn-Token Service validates the access token.

   6.  The Txn-Token Service populates the Txn-Token's sub claim
       following the rules specified in OAUTH-TXN-TOKENS
       (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
       oauth-transaction-tokens.html).  The sub claim is determined
       based on the subject_token provided in the request, according to
       the conditions and rules defined in the base Transaction Tokens
       specification.  This ensures that the principal is properly
       represented in the Txn-Token.

   7.  The Txn-Token Service copies the access token's clientId claim to
       the Txn-Token's act field.  Any nested structure within the
       clientId claim is preserved.  If the access token contains an act
       claim, that value MAY be used instead of clientId.

   8.  The Txn-Token Service issues the Txn-Token to the requesting
       workload.

3.2.2.  Autonomous Flow

   When the agent application operates autonomously, the following steps
   occur:

   1.  The agent application initiates a task based on an event or
       scheduled assignment.

   2.  The agent application calls an external endpoint.  OAuth
       challenge flow starts.

   3.  The agent application authenticates using an OAuth 2.0 RFC6749
       (https://tools.ietf.org/html/rfc6749).  When an autonomous agent
       (no human resource owner) needs to call another resource server
       using OAuth, it follows the Client Credentials Grant defined
       explicitly in RFC6749 (https://tools.ietf.org/html/rfc6749).

   4.  The agent application uses the access token to call the external
       endpoint.

   5.  The external endpoint submits the received access token along
       with its Subject token to the Txn-Token Service.  Subject token
       requirements are specified in OAUTH-TXN-TOKENS
       (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
       oauth-transaction-tokens.html).

   6.  The Txn-Token Service validates the access token.





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   7.  The Txn-Token Service populates the Txn-Token's sub claim
       following the rules specified in OAUTH-TXN-TOKENS
       (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
       oauth-transaction-tokens.html).  The sub claim is determined
       based on the subject_token provided in the request.  For
       autonomous agents, this typically represents the agent's own
       identity.

   8.  The Txn-Token Service copies the access token's sub or clientId
       claim to the Txn-Token's act field.  Any nested structure is
       preserved.  The act field identifies the agent performing the
       autonomous action.

3.3.  Flow Diagrams

3.3.1.  Principal-Initiated Flow

   Based on the updated flow, here's a more detailed RFC-style flow
   diagram:

Principal    Agent App    External    Authorization   Txn-Token
                         Endpoint        Server        Service
   |            |           |              |             |
   | Invoke     |           |              |             |
   | agent task |           |              |             |
   |----------->|           |              |             |
   |            |           |              |             |
   |            | Call external API        |             |
   |            |---------->|              |             |
   |            |           |              |             |
   |            |   OAuth Challenge        |             |
   |            |<----------|              |             |
   |            |           |              |             |
   |            | Initiate Auth Code Flow  |             |
   |            |------------------------->|             |
   |            |           |              |             |
   |            | Auth Code                |             |
   |            |<-------------------------|             |
   |            |           |              |             |
   |            | Exchange code for token  |             |
   |            |------------------------->|             |
   |            |           |              |             |
   |            | Access Token (AT1)       |             |
   |            | w/ sub, clientId claims  |             |
   |            |<-------------------------|             |
   |            |           |              |             |
   |            | Call with AT1            |             |
   |            |---------->|              |             |



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   |            |           |              |             |
   |            |           | Request Txn-Token          |
   |            |           | with AT1, Subject token    |
   |            |           | as param     |             |
   |            |           |--------------------------->|
   |            |           |              |             |
   |            |           |              |    Validate AT1
   |            |           |              |    Extract claims
   |            |           |              |    Set sub from Subject token
   |            |           |              |    Set act from AT1.clientId
   |            |           |              |             |
   |            |           |              |             |
   |            |           |              |             |
   |            |           |              |             |
   |            |           | Txn-Token    |             |
   |            |           |<---------------------------|
   |            |           |              |             |

Legend:
----> : Request flow
<---- : Response flow
  |   : Component boundary

   Notes: 1.  AT1 refers to the access token obtained by Agent App 2.
   The External Endpoint uses its own access token to call Txn-Token
   Service 3.  AT1 is passed as a parameter in the Txn-Token request 4.
   The flow shows detailed OAuth 2.0 Authorization Code flow steps 5.
   Token validation and claim extraction steps are shown in the Txn-
   Token Service

3.3.2.  Autonomous Flow

Agent App    External    Authorization   Txn-Token
            Endpoint        Server        Service
    |           |              |             |
    | Self-     |              |             |
    | triggered |              |             |
    | event     |              |             |
    |--+        |              |             |
    |  |        |              |             |
    |<-+        |              |             |
    |           |              |             |
    | Call external API        |             |
    |---------->|              |             |
    |           |              |             |
    |   OAuth Challenge        |             |
    |<----------|              |             |
    |           |              |             |



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    | Client Credentials Grant |             |
    |------------------------->|             |
    |           |              |             |
    | Access Token (AT1)       |             |
    |  sub, aud claims         |             |
    |<-------------------------|             |
    |           |              |             |
    | Call with AT1            |             |
    |---------->|              |             |
    |           |              |             |
    |           | Request Txn-Token          |
    |           | with AT1, Subject token    |
    |           | as param     |             |
    |           |--------------------------->|
    |           |              |             |
    |           |              |    Validate AT1
    |           |              |    Extract claims
    |           |              |    Set sub from aud
    |           |              |    Set act.sub from clientId or sub
    |           |              |             |
    |           |              |             |
    |           |              |             |
    |           | Txn-Token    |             |
    |           |<---------------------------|
    |           |              |             |

Legend:
----> : Request flow
<---- : Response flow
  |   : Component boundary
  +   : Internal process
--+   : Self-triggered event

Notes:
* AT1: Access token obtained via Client Credentials Grant
* External Endpoint uses subject token for authenticating itself to Txn-Token Service
* AT1 is included as parameter in Txn-Token request
* Self-triggered events can be scheduled tasks or external triggers
* Token validation includes signature and claims verification

3.4.  Replacement tokens

   Txn-Token Service provides capability to get a replacement Txn-Token
   as defined in the OAUTH-TXN-TOKENS.replacement flow
   (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-oauth-
   transaction-tokens.html#name-creating-replacement-txn-to).  If the
   original Txn-Token used to get replacement token contains 'actor' and
   'principal' claims then in the replaced Txn-Token, the values of the



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   'actor' and 'principal' MUST remain unchanged similar to 'txn', sub
   and 'aud' claims.

3.5.  Txn-Token Format

3.5.1.  JWT Header

   No changes to the JWT header from the base specification: typ MUST be
   txntoken+jwt, with a signing key identifier such as kid.

3.5.2.  JWT Body Claims

   The Txn-Token body augments the base claim set with the act field for
   agent context.  Existing claims like txn, sub, aud, iss, iat, exp,
   scope, tctx, and req_wl retain identical semantics, population rules,
   and immutability guarantees as defined in OAUTH-TXN-TOKENS
   (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-oauth-
   transaction-tokens.html).

   In this example, the agent is 3rd party and not part of trust domain.
   It hits API Gateway in trust domain and API Gateway requests Txn-
   Token from Txn-token Service using access token received from 3P
   agent and its own subject token (to authenticate with Txn-Token
   Service).  Requesting workload is API Gateway.  Agent is agent-
   identity-1 (clientId in the access token issued to 3P agent to act on
   behalf of user:alice)

   {
     "txn": "c2dc3992-2d65-483a-93b5-2dd9f02c276e",
     "sub": "user:alice@example.com", // if its human initiated
     "aud": "https://trading.trust-domain.example/stocks",
     "iss": "https://txn-svc.trust-domain.example",
     "iat": 1697059200,
     "exp": 1697059500,
     "purp": "trade.stocks",
     "tctx": {
       "action": "BUY",
       "ticker": "MSFT",
       "quantity": "100"
     },
     "req_wl": "apigateway.trust-domain.example", // API gateway requests Txn-token
     "act": {
        "sub":"agent-identity-1" // 3P agent hitting API gateway owned by trust domain
     }
   }






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3.6.  Agentic Context

   The Txn-Token MAY contain an agentic_ctx claim.  Txn-Tokens are
   increasingly used in environments where transactions are executed by
   or with the assistance of autonomous or semi-autonomous agents (for
   example, Large Language Model (LLM)–based agents, workflow
   orchestrators, and policy-driven automation components).  In such
   deployments, relying exclusively on subject identity and generic
   transaction parameters is insufficient to make robust authorization
   decisions.  Additional information about the agent that is
   interpreting and acting on the transaction is often required.

3.6.1.  Field definitions and population

   All fields are OPTIONAL as some of these fields may not be avaiable
   for 3P (third party agents) connecting to your external service
   (edge) within trust domain.  However, for internal agents within
   trust domain, you MAY get following information.  For 3P agents
   outside your trust domain, as called out above, you will be able to
   get act claim information using access token and rest of the below
   fields in agentic_context may or may not be available.

   *  *prov (Provenance)*: Defines the "Behavioral DNA" of the agent.
      The manifest_hash is a cryptographic digest of the agent’s system
      instructions and core logic, ensuring the agent’s "guardrails"
      have not been modified.  The manifest_hash is an opaque key.
      Resource Servers are expected to resolve this hash against a local
      or remote policy store to determine the specific behavioral
      guardrails applied to the agent at that version.

   *  *posture (Environmental Integrity)*: Details the security tier of
      the runtime.  This includes hardware-backed proof (e.g., TEE) that
      the agent is isolated from the host OS or cloud provider.

   *  *identity (Workload Origin)*: Captures the specific machine-actor
      instance.  The workload_id distinguishes the instrument (the agent
      software) from the subject (the end-user).

   The agentic_ctx claim is populated during the token exchange process
   by the Transaction Token Service (TTS), which serves as the
   authoritative source for the agent’s operational identity.  This
   context MAY be derived from various but not limited to sources such
   as : (1) Static Manifests, which include cryptographic hashes of the
   agent’s system prompt, model configuration, and registered source
   code identifiers; (2) Environmental Posture, consisting of telemetry
   injected by the execution environment or API gateway, such as the
   hardware security level (e.g., TEE measurements) or network origin;
   and (3) Workload Mapping, where attributes are mirrored from the



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   agent’s primary workload identity (e.g., SPIFFE or OIDC claims).  By
   centralizing this population at the TTS, the agentic_ctx provides a
   consistent and tamper-resistant representation of the agent’s
   "persona."  This allows downstream resource servers to evaluate the
   agent’s integrity and origin against local safety policies
   independently of the specific actions or permissions requested in the
   transaction.

   To ensure the integrity of the agentic_ctx, the Transaction Token
   Service (TTS) MUST not rely on self-reported data from the agent.
   Instead, it populates these fields through a Verified Exchange model.
   Hardware-backed fields like posture and tee are derived from
   cryptographic Attestation Documents generated by the agent's
   execution environment (e.g., a Trusted Execution Environment) and
   verified by the TTS against cloud provider roots of trust.  Software-
   related fields, such as the manifest_hash, are retrieved via a
   Registry-First approach: the TTS performs an out-of-band lookup in a
   secure Agent Registry using the agent’s authenticated client_id,
   ensuring that the "behavioral fingerprint" in the token matches the
   developer’s registered configuration rather than a potentially
   tampered runtime state.  Finally, the identity claims are mirrored
   from the transport layer (e.g., mTLS certificates or SPIFFE SVIDs),
   binding the token to the specific verified workload instance.

3.6.2.  Example of agentic_ctx with additional context

   {
     "agentic_ctx": {
       "prov": {
         "manifest_hash": "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
         "model_id": "llama-3.1-70b-v1",
         "version": "2.4.1"
       },
       "posture": {
         "tee": "aws-nitro-enclave",
         "assurance": "high",
         "boot_gold": true
       },
       "identity": {
         "workload_id": "spiffe://prod.acme.com/billing-agent",
         "origin_node": "node-77-east-1"
       }
     }
   }







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3.6.3.  Implementation Note: Integrity and Resolution

   The fields within agentic_ctx represent a "Statement of Posture"
   rather than a set of permissions.  To avoid authorization failure,
   implementations should ensure that: * *Registry Synchronization*: The
   manifest_hash is treated as a lookup key.  Resource Servers should
   maintain or have access to a known-good database of hashes to map
   cryptographic signatures to behavioral guardrails. * *Hardware Roots
   of Trust*: When posture claims are present, the Transaction Token
   Service MUST verify the underlying attestation document against the
   hardware manufacturer's public keys. * *Non-Collusion*: The
   agentic_ctx is distinct from the sub claim.  While the sub identifies
   the authorizing principal, the agentic_ctx identifies the machine-
   actor.  Authorization logic SHOULD evaluate the intersection of both
   identities.

4.  Multi-agent flows

   In complex agentic workflows, a transaction often originates from a
   3rd-party (3P) agent and propagates through one or more 1st-party
   (1P) agents within the local trust domain.  To maintain Zero Trust
   integrity, this specification uses a structured Postured Lineage
   within the agentic_ctx.  This ensures that downstream Resource
   Servers can evaluate the security posture of the entire chain, rather
   than relying solely on the identity of the immediate caller.

4.1.  The Bifurcated Trust Model

   The agentic_ctx differentiates between two types of actors in a
   chain:

   *  *The Originator (External/3P)*: The entry point of the request
      into the trust domain.  Because the hardware and software of 3P
      agents are outside local control, their context is Asserted via
      identity federation.  Posture and provenance fields for these
      actors are typically marked as unverified or none.

   *  *The Current Actor (Internal/1P)*: The agent currently executing
      the request.  For internal agents, the context is Verified by the
      Transaction Token Service (TTS) using hardware attestation and
      registry-based manifest lookups.










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4.2.  Monotonic Attenuation of Trust

   A chain’s security posture is only as strong as its weakest link.
   The TTS MUST calculate a min_assurance_level during every token
   replacement flow.  If a "High-Trust" internal agent is triggered by a
   "Low-Trust" 3P originator, the transaction’s overall assurance level
   remains low.  This prevents Identity Laundering, where unverified
   external agents bypass security guardrails by proxying requests
   through internal services.  The Transaction Token Service (TTS)
   determines the min_assurance_level by performing a comparative risk
   analysis during the token replacement flow.  It essentially
   identifies the "weakest link" in the execution chain by comparing the
   posture of the incoming token with the verified posture of the new
   requesting agent.

4.2.1.  Delegation via Replacement Flow

   When an internal agent (the "Delegatee") requires a Transaction Token
   to continue a chain initiated by another actor (the "Delegator"), it
   MUST follow the replacement flow procedures defined in OAUTH-TXN-
   TOKENS (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
   oauth-transaction-tokens.html) with the following modifications:

   *  *Subject Immutability*: The txn and sub (principal) claims MUST be
      copied from the subject_token to the new Transaction Token without
      modification.

   *  *Lineage Preservation*: The TTS MUST extract the identity of the
      Delegator from the incoming token and append it to the txn_path
      array.

   *  *Context Enrichment*: The TTS MUST populate the current_actor
      object with verified telemetry (TEE posture, manifest hashes)
      corresponding to the Delegatee.

4.2.2.  Multi-agent example JWT body claims

   This example represents a delegated state: a 3rd-party Assistant (3p-
   assistant-ext-99) has initiated a task, which is now being executed
   by an internal, 1st-party Billing Agent (1p-billing-svc-v2) running
   in a secure enclave.










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   {
     "txn": "abc-123-xyz",
     "sub": "user_8821@example.com",
     "iss": "[https://txn-svc.trust-domain.example](https://txn-svc.trust-domain.example)",
     "iat": 1712850000,
     "exp": 1712850300,
     "req_wl": "apigateway.trust-domain.example", // API gateway requests Txn-token
     "agentic_ctx": {
       "current_actor": {
         "identity": {
           "workload_id": "1p-billing-svc-v2",
           "origin_node": "internal-cluster-alpha-node-4"
         },
         "posture": {
           "tee": "aws-nitro-enclave",
           "assurance": "high"
         },
         "prov": {
           "manifest_hash": "sha256:4455..."
         }
       },
       "originator": {
         "identity": { "workload_id": "3p-assistant-ext-99" },
         "posture": {
           "tee": "unverified",
           "assurance": "low"
         },
         "prov": { "manifest_hash": "none" }
       },
       "chain_metadata": {
         "hop_count": 2,
         "min_assurance_level": "low",
         "txn_path": ["3p-assistant-ext-99", "1p-billing-svc-v2"]
       }
     }
   }

4.2.3.  Loop prevention

   To prevent infinite recursion in autonomous agentic loops, the
   txn_path MUST be updated at every hop.  The TTS MUST append the
   current workload_id to the path.  If an agent receives a token where
   its own workload_id is already present in the txn_path, the request
   MUST be rejected.







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5.  Security Considerations

   1.   All the security considerations mentioned in OAUTH-TXN-TOKENS
        (https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-
        oauth-transaction-tokens.html) apply.

   2.   Token Replay Protection Implementations MUST enforce strict
        token lifetime validation.  The short-lived nature of
        Transaction Tokens helps mitigate replay attacks, but
        implementations SHOULD also consider:

        *  Implementing token tracking mechanisms within trust domains

        *  Validating token usage context

   3.   Actor Identity Security

        *  Implementations MUST validate act claims in tokens

        *  The Txn-Token Service MUST verify the authenticity of actor
           context before token issuance

        *  During replacement flow, Txn-Token Service MUST NOT modify
           the act field in the incoming Txn-Token

   4.   Principal Context Protection

        *  Systems MUST prevent unauthorized modifications to the sub
           claim during token propagation.  Txn-Tokens are
           cryptographically signed to ensure integrity.

        *  During replacement flow, Txn-Token Service MUST NOT modify
           the sub claim in the incoming Txn-Token

        *  The Txn-Token Service MUST follow the subject population
           rules defined in OAUTH-TXN-TOKENS (https://drafts.oauth.net/
           oauth-transaction-tokens/draft-ietf-oauth-transaction-
           tokens.html) to ensure proper principal representation

   5.   Transaction Chain Integrity

        *  Implementations MUST maintain cryptographic integrity of the
           token chain

        *  Services MUST validate tokens at trust domain boundaries

        *  Systems MUST implement protection against token tampering
           during service-to-service communication



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   6.   AI Agent Specific Controls

        *  Implementations MUST enforce scope boundaries for AI agent
           operations

        *  Systems SHOULD implement behavioral monitoring for AI agent
           activities by logging act and sub claims in audit logs

        *  Systems MUST maintain audit trails of AI agent activities

   7.   Token Transformation Security

        *  The Txn-Token Service MUST validate all claims during access
           token to Txn-Token conversion

        *  Implementations MUST verify signatures and formats of all
           tokens

        *  Systems MUST prevent unauthorized manipulation during token
           transformation

        *  The Txn-Token Service MUST ensure that the act field
           accurately represents the agent identity from the access
           token

   8.   Replacement Token Considerations

        *  Systems MUST verify the authenticity and validity of original
           tokens before replacement

        *  Systems MUST implement controls to prevent unauthorized
           replacement requests

        *  The immutability of act and sub claims during replacement
           ensures consistent identity context throughout the
           transaction lifecycle

   9.   Infrastructure Security

        *  All component communications MUST use secure channels

        *  Implementations MUST enforce strong authentication of the
           Authorization Server

        *  Systems MUST implement regular rotation of cryptographic keys

        *  Trust domain boundaries MUST be clearly defined and enforced




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   10.  Prevention of Identity Laundering

        *  Implementations MUST enforce Monotonic Attenuation of the
           min_assurance_level.

        *  The TTS MUST NOT allow a replacement token to have a higher
           assurance level than the incoming subject token, even if the
           current actor is running in a High-Assurance environment.

        *  This prevents a low-trust 3rd-party originator from
           "laundering" its identity through a high-trust internal agent
           to bypass security guardrails at the Resource Server.

   11.  Integrity of the Agent Registry

        *  The security of the prov (Provenance) claims relies entirely
           on the integrity of the Agent Registry.  If an attacker can
           modify the registry to associate a malicious manifest_hash
           with a legitimate workload_id, they can trick the TTS into
           asserting high software integrity for tampered code.

        *  Access to the Agent Registry MUST be restricted to authorized
           deployment pipelines and protected with strong integrity
           controls.

   12.  Hardware Attestation Forgery

        *  When posture claims indicate the use of a Trusted Execution
           Environment (TEE), the TTS MUST verify the underlying
           Attestation Document against the hardware manufacturer’s Root
           of Trust.

        *  Failure to verify these signatures allows a compromised host
           to spoof a "High" assurance posture, leading to unauthorized
           access to sensitive data.

   13.  Loop Detection and Recursion Limits

        *  The use of the txn_path is REQUIRED to prevent infinite
           recursion in autonomous agentic workflows.

        *  Resource Servers and the TTS SHOULD also enforce a maximum
           hop_count to prevent resource exhaustion attacks.  If the
           path exceeds a defined threshold, the transaction MUST be
           terminated.

   14.  Data Leakage in Lineage Propagation




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        *  The agentic_ctx may contain sensitive internal information,
           such as origin_node or specific workload_id structures.

        *  When a 1st-party agent calls an external 3rd-party service,
           the TTS MUST strip these internal-only fields from the token
           to prevent infrastructure leakage.

        *  Only the minimum necessary identity context should be
           egressed from the trust domain.

6.  References

6.1.  Normative References

   RFC2119 (https://datatracker.ietf.org/doc/html/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 (https://www.rfc-editor.org/rfc/rfc2119).

   RFC8174 (https://datatracker.ietf.org/doc/html/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

   RFC6749 (https://tools.ietf.org/html/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
   (https://www.rfc-editor.org/rfc/rfc6749).

   RFC7519 (https://tools.ietf.org/html/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
   (https://www.rfc-editor.org/rfc/rfc7519).

   RFC7515 (https://tools.ietf.org/html/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
   (https://www.rfc-editor.org/rfc/rfc7515).

   RFC8693 (https://tools.ietf.org/html/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 (https://www.rfc-
   editor.org/rfc/rfc8693).







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   RFC9068 (https://tools.ietf.org/html/rfc9068) Bertocci, V., "JSON Web
   Token (JWT) Profile for OAuth 2.0 Access Tokens", RFC 9068, DOI
   10.17487/RFC9068, October 2021, https://www.rfc-editor.org/rfc/
   rfc9068 (https://www.rfc-editor.org/rfc/rfc9068).

   RFC9396 (https://datatracker.ietf.org/doc/html/rfc9396) T.
   Lodderstedt, J.  Richer, B.  Campbell, "OAuth 2.0 Rich Authorization
   Requests", RFC 9396, DOI 10.17487/RFC9396, May 2023, https://www.rfc-
   editor.org/rfc/rfc9396 (https://www.rfc-editor.org/rfc/rfc9396).

   OAUTH-TXN-TOKENS (https://datatracker.ietf.org/doc/draft-
   tulshibagwale-oauth-transaction-tokens) Atul Tulshibagwale, George
   Fletcher, Pieter Kasselman, "OAuth Transaction Tokens",
   https://drafts.oauth.net/oauth-transaction-tokens/draft-ietf-oauth-
   transaction-tokens.html (https://drafts.oauth.net/oauth-transaction-
   tokens/draft-ietf-oauth-transaction-tokens.html)

Appendix A.  Acknowledgments

   name: Dr. Chunchi (Peter) Liu email: Liuchunchi(Peter)
   <liuchunchi=40huawei.com@dmarc.ietf.org>

Appendix B.  Contributors

   name: Atul Tulshibagwale org: SGNL email: atul@sgnl.ai

Author's Address

   ASHAY RAUT
   Email: asharaut@amazon.com





















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