Remove non-protocol claims and make ledger optional
Move 6 metadata claims (pol_timestamp, inp_classification, exec_time_ms, regulated_domain, model_version, witnessed_by) from registered JWT claims to recommended ext extension keys. Use short key names for spec-defined extensions. Make audit ledger explicitly optional: rename pseudocode parameter from ledger to ect_store, mark architecture diagram ledger layer as optional, add conditional append logic, and soften Audit Ledger Interface language. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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@@ -292,8 +292,8 @@ between the identity layer and the application layer:
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v
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+--------------------------------------------------+
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| Ledger Layer (Immutable Record) |
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| "All ECTs appended to audit ledger" |
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| Optional: Audit Ledger (Immutable Record) |
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| "ECTs MAY be appended to an audit ledger" |
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+--------------------------------------------------+
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~~~
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{: #fig-layers title="WIMSE Extension Architecture Layers"}
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@@ -345,7 +345,8 @@ The receiving agent (Agent B) verifies in order:
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2. ECT (this extension): Records what Agent A did, what policy was
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evaluated, and what precedent tasks exist.
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3. Ledger: Appends the verified ECT to the audit ledger.
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3. Ledger (if deployed): Appends the verified ECT to the audit
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ledger.
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# Execution Context Token Format {#ect-format}
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@@ -592,32 +593,31 @@ ext:
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that do not understand extension claims MUST ignore them.
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To avoid key collisions between different domains, extension
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key names MUST use reverse domain notation (e.g.,
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"com.example.custom_field"). Implementations MUST NOT use
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unqualified key names within the "ext" object. To prevent
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abuse and excessive token size, the serialized JSON
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representation of the "ext" object SHOULD NOT exceed 4096
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bytes, and the JSON nesting depth within the "ext" object
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SHOULD NOT exceed 5 levels. Implementations SHOULD reject
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ECTs whose "ext" claim exceeds these limits.
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key names SHOULD use reverse domain notation (e.g.,
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"com.example.custom_field") to avoid collisions between
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independently developed extensions. To prevent abuse and
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excessive token size, the serialized JSON representation of
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the "ext" object SHOULD NOT exceed 4096 bytes, and the JSON
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nesting depth within the "ext" object SHOULD NOT exceed 5
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levels. Implementations SHOULD reject ECTs whose "ext" claim
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exceeds these limits.
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The following extension keys are RECOMMENDED for common use
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cases. These are not registered claims; they are carried
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within the "ext" object:
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The following extension keys are defined by this specification
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for common use cases. Because these keys are documented here,
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they use short names without reverse domain prefixes:
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- "org.ietf.wimse.exec\_time\_ms": Integer. Execution duration in
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milliseconds.
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- "org.ietf.wimse.regulated\_domain": String. Regulatory domain
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(e.g., "medtech", "finance", "military").
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- "org.ietf.wimse.model\_version": String. AI/ML model version.
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- "org.ietf.wimse.witnessed\_by": Array of StringOrURI. Identifiers
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of third-party entities that the issuer claims observed the
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- "exec\_time\_ms": Integer. Execution duration in milliseconds.
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- "regulated\_domain": String. Regulatory domain (e.g.,
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"medtech", "finance", "military").
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- "model\_version": String. AI/ML model version.
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- "witnessed\_by": Array of StringOrURI. Identifiers of
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third-party entities that the issuer claims observed the
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task. Note: this is self-asserted; for verifiable witness
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attestation, witnesses should submit independent signed ECTs.
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- "org.ietf.wimse.inp\_classification": String. Data sensitivity
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classification (e.g., "public", "confidential", "restricted").
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- "org.ietf.wimse.pol\_timestamp": NumericDate. Time at which the
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policy decision was made, if distinct from "iat".
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- "inp\_classification": String. Data sensitivity classification
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(e.g., "public", "confidential", "restricted").
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- "pol\_timestamp": NumericDate. Time at which the policy
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decision was made, if distinct from "iat".
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## Complete ECT Example
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@@ -644,10 +644,10 @@ The following is a complete ECT payload example:
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"out_hash": "sha-256:LCa0a2j_xo_5m0U8HTBBNBNCLXBkg7-g-YpeiGJm564",
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"ext": {
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"org.ietf.wimse.pol_timestamp": 1772064145,
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"org.ietf.wimse.exec_time_ms": 245,
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"org.ietf.wimse.regulated_domain": "medtech",
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"org.ietf.wimse.model_version": "clinical-reasoning-v4.2"
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"pol_timestamp": 1772064145,
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"exec_time_ms": 245,
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"regulated_domain": "medtech",
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"model_version": "clinical-reasoning-v4.2"
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}
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}
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~~~
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@@ -699,8 +699,8 @@ enabling auditors to reconstruct the complete workflow and verify
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that required predecessor tasks were recorded before dependent
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tasks.
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DAG validation is performed against the audit ledger, which
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serves as the authoritative store of previously verified ECTs.
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DAG validation is performed against the ECT store — either an
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audit ledger or the set of parent ECTs received inline.
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## Validation Rules
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@@ -752,14 +752,14 @@ the following DAG validation steps:
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The following pseudocode describes the DAG validation procedure:
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~~~ pseudocode
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function validate_dag(ect, ledger, clock_skew_tolerance):
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function validate_dag(ect, ect_store, clock_skew_tolerance):
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// Step 1: Uniqueness check
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if ledger.contains(ect.jti, ect.wid):
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if ect_store.contains(ect.jti, ect.wid):
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return error("ECT ID already exists")
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// Step 2: Parent existence and temporal ordering
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for parent_id in ect.par:
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parent = ledger.get(parent_id)
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parent = ect_store.get(parent_id)
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if parent is null:
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return error("Parent task not found: " + parent_id)
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if parent.iat >= ect.iat + clock_skew_tolerance:
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@@ -767,14 +767,14 @@ function validate_dag(ect, ledger, clock_skew_tolerance):
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// Step 3: Cycle detection (with traversal limit)
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visited = set()
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result = has_cycle(ect.jti, ect.par, ledger, visited,
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result = has_cycle(ect.jti, ect.par, ect_store, visited,
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max_ancestor_limit)
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if result is error or result is true:
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return error("Circular dependency or depth limit exceeded")
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return success
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function has_cycle(target_jti, parent_ids, ledger,
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function has_cycle(target_jti, parent_ids, ect_store,
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visited, max_depth):
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if visited.size() >= max_depth:
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return error("Maximum ancestor traversal limit exceeded")
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@@ -784,9 +784,9 @@ function has_cycle(target_jti, parent_ids, ledger,
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if parent_id in visited:
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continue
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visited.add(parent_id)
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parent = ledger.get(parent_id)
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parent = ect_store.get(parent_id)
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if parent is not null:
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result = has_cycle(target_jti, parent.par, ledger,
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result = has_cycle(target_jti, parent.par, ect_store,
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visited, max_depth)
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if result is error or result is true:
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return result
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@@ -883,7 +883,7 @@ fails.
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~~~ pseudocode
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function verify_ect(ect_jws, verifier_id,
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trust_domain_keys, ledger):
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trust_domain_keys, ect_store):
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// Parse JWS
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(header, payload, signature) = parse_jws(ect_jws)
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@@ -944,29 +944,30 @@ function verify_ect(ect_jws, verifier_id,
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["approved", "rejected", "pending_human_review"]:
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return reject("Invalid pol_decision value")
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// Validate DAG (against ledger or inline parent ECTs)
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result = validate_dag(payload, ledger,
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// Validate DAG (against ECT store or inline parent ECTs)
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result = validate_dag(payload, ect_store,
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clock_skew_tolerance)
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if result is error:
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return reject("DAG validation failed")
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// All checks passed; append to ledger
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ledger.append(payload)
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// All checks passed; record if store is available
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if ect_store is not null:
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ect_store.append(payload)
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return accept
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~~~
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{: #fig-verification title="ECT Verification Pseudocode"}
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# Audit Ledger Interface {#ledger-interface}
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ECTs are designed to be recorded in an immutable audit ledger for
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compliance verification and post-hoc analysis. This specification
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defines required properties for the ledger but does not mandate
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a specific storage technology. Implementations MAY use
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append-only logs, databases with cryptographic commitment schemes,
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distributed ledgers, or any storage mechanism that provides the
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required properties.
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ECTs MAY be recorded in an immutable audit ledger for compliance
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verification and post-hoc analysis. A ledger is RECOMMENDED for
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regulated environments but is not required for point-to-point
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operation. This specification does not mandate a specific storage
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technology. Implementations MAY use append-only logs, databases
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with cryptographic commitment schemes, distributed ledgers, or
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any storage mechanism that provides the required properties.
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An audit ledger implementation MUST provide:
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When an audit ledger is deployed, the implementation MUST provide:
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1. Append-only semantics: Once an ECT is recorded, it MUST NOT be
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modified or deleted.
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@@ -1031,7 +1032,7 @@ Human Release Manager:
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exec_act: approve_release
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pol: release_approval_policy pol_decision: approved
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pol_enforcer: spiffe://meddev.example/human/release-mgr-42
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ext: {org.ietf.wimse.witnessed_by: [...]} (extension metadata)
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ext: {witnessed_by: [...]} (extension metadata)
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~~~
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{: #fig-medtech-sdlc title="Medical Device SDLC Workflow"}
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@@ -1222,7 +1223,7 @@ ECTs do not independently verify that:
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The trustworthiness of ECT claims depends on the trustworthiness
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of the signing agent. To mitigate single-agent false claims,
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regulated environments SHOULD use the "org.ietf.wimse.witnessed_by"
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regulated environments SHOULD use the "witnessed_by"
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extension key (carried in "ext") to include independent
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third-party observers at critical decision points. However,
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this value is self-asserted by the ECT issuer: the listed
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@@ -1234,7 +1235,7 @@ did not participate.
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### Witness Attestation Model {#witness-attestation-model}
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To address the self-assertion limitation of the
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"org.ietf.wimse.witnessed_by" extension, witnesses SHOULD submit their
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"witnessed_by" extension, witnesses SHOULD submit their
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own independent signed ECTs to the audit ledger attesting to the
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observed task. A witness attestation ECT:
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@@ -1246,7 +1247,7 @@ observed task. A witness attestation ECT:
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- MUST set "pol_decision" to "approved" to indicate the witness
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confirms the observation.
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When a task's "org.ietf.wimse.witnessed_by" extension lists one or more
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When a task's "witnessed_by" extension lists one or more
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witnesses, auditors SHOULD verify that corresponding witness
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attestation ECTs exist in the ledger for each listed witness. A
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mismatch between the extension value and the set of independent
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@@ -1352,7 +1353,7 @@ Mitigations include:
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- Independent ledger maintenance: The ledger SHOULD be maintained
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by an entity independent of the workflow agents.
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- Witness attestation: Using the "org.ietf.wimse.witnessed_by" extension
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- Witness attestation: Using the "witnessed_by" extension
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key in "ext" to include independent third-party observers.
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- Cross-verification: Multiple independent ledger replicas can be
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compared for consistency.
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@@ -1927,7 +1928,7 @@ Task 5 (Human Release Manager Approval):
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"pol_decision": "approved",
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"pol_enforcer": "spiffe://meddev.example/human/release-mgr-42",
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"ext": {
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"org.ietf.wimse.witnessed_by": [
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"witnessed_by": [
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"spiffe://meddev.example/audit/qa-observer-1"
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]
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}
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@@ -1938,7 +1939,7 @@ The resulting DAG records the complete SDLC: spec review preceded
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implementation, implementation preceded testing, testing preceded
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build, and a human release manager approved the final release.
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The "ext" object in task 5 carries witness metadata via
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the "org.ietf.wimse.witnessed_by" extension key.
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the "witnessed_by" extension key.
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~~~
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task-...-0001 (review_requirements_spec)
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