Internet Engineering Task Force T. Jacobs Internet-Draft KTS Global Intended status: Experimental 12 September 2026 Expires: 16 March 2027 Web4 Evidence Receipts draft-jacobs-web4-evidence-receipts-00 Abstract This document defines durable, cryptographically verifiable receipts for assessment, authority, policy, claim, and node-lifecycle events without requiring publication of protected evidence. 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/. 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 material or to cite them other than as "work in progress." This Internet-Draft will expire on 16 March 2027. 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 and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Jacobs Expires 16 March 2027 [Page 1] Internet-Draft Web4 Evidence Receipts September 2026 Table of Contents 1. Conventions and Terminology . . . . . . . . . . . . . . . . . 2 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Receipt Events . . . . . . . . . . . . . . . . . . . . . . . 2 4. Receipt Envelope . . . . . . . . . . . . . . . . . . . . . . 2 5. Issuance and Signing . . . . . . . . . . . . . . . . . . . . 3 6. Retention and Resolution . . . . . . . . . . . . . . . . . . 3 7. Evidence Commitments . . . . . . . . . . . . . . . . . . . . 3 8. Research References . . . . . . . . . . . . . . . . . . . . . 3 9. Verification . . . . . . . . . . . . . . . . . . . . . . . . 3 10. Relationship to Research Artifacts . . . . . . . . . . . . . 4 11. Security Considerations . . . . . . . . . . . . . . . . . . . 4 12. Privacy Considerations . . . . . . . . . . . . . . . . . . . 4 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 14. Normative References . . . . . . . . . . . . . . . . . . . . 5 15. Informative References . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 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] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2. Introduction This document defines durable, integrity-protected Evidence Receipts for material events in federated and agent-operated systems. 3. Receipt Events Profiles MAY define events including assessment issued, admission granted or denied, policy applied, authority granted or revoked, claim challenged or superseded, verification performed, and node lifecycle changes. 4. Receipt Envelope A receipt MUST identify its identifier, event type, actor, subject or object, governing policy, event time, status mechanism, and proof. When an event relies on evidence, the receipt MUST carry references or commitments required by the profile. Jacobs Expires 16 March 2027 [Page 2] Internet-Draft Web4 Evidence Receipts September 2026 { "receipt_id": "urn:web4:receipt:01JEXAMPLE", "event_type": "assessment_issued", "actor_id": "did:example:evaluator-1", "object_id": "urn:web4:assertion:01JEXAMPLE", "policy_id": "urn:web4:policy:admission:v1", "occurred_at": "2026-09-12T13:59:00Z", "status_uri": "https://status.example/receipts/01JEXAMPLE", "proof": { "type": "ExampleProof", "verification_method": "did:example:evaluator-1#key-1", "value": "BASE64URL-SIGNATURE" } } 5. Issuance and Signing An issuer MUST integrity-protect each receipt. Corrections MUST use a linked corrective or superseding receipt rather than silent mutation. 6. Retention and Resolution Policy MUST specify a retention class or period. Status MUST remain resolvable for the required retention period. 7. Evidence Commitments A private artifact MAY be represented by a cryptographic commitment. The profile MUST identify the algorithm and any canonicalization, salting, keying, or disclosure procedure. 8. Research References A receipt MAY refer to a versioned research artifact using a persistent identifier. Reproducibility-sensitive references SHOULD use a version-specific DOI. 9. Verification A Verifier MUST authenticate the issuer, validate integrity, resolve status, check temporal and policy context, and verify disclosed commitments before relying on a receipt. Jacobs Expires 16 March 2027 [Page 3] Internet-Draft Web4 Evidence Receipts September 2026 10. Relationship to Research Artifacts Broader Web4 architectural work is described informatively in [I-D.reilly-web4]. Informative research materials MAY be published as versioned scholarly artifacts, including DOI-addressable records. A research artifact is not required for conformance unless expressly incorporated as a Normative Reference by a named profile. Referencing or verifying an artifact does not establish the truth of its conclusions, regulatory approval, certification, security, legal compliance, or IETF endorsement. A Conforming Implementation MUST NOT require access to KCoordinate, KQAS, or another protected internal assessment method unless a separate deployment agreement selects that implementation. 11. Security Considerations Implementations MUST authenticate issuers, validate proof integrity, check proof purpose, enforce temporal validity, and resolve current status before relying on an object. Implementations MUST address identifier confusion, issuer impersonation, key compromise, algorithm downgrade, replay, stale status, unauthorized supersession, cross-policy confusion, canonicalization ambiguity, denial of service, and fail-open handling of indeterminate validity. Evidence commitments can confirm correspondence with committed bytes but do not prove truth, completeness, legality, provenance, or fitness for purpose. Profiles SHOULD define privacy-preserving commitment procedures for low-entropy artifacts. 12. Privacy Considerations Persistent identifiers, status queries, proofs, policy references, and linked receipts can enable correlation. Implementations MUST minimize disclosed data and SHOULD use unlinkable or pairwise identifiers where they satisfy policy. Private evidence MAY remain undisclosed and be represented by a cryptographic commitment. Retention and erasure requirements MUST be specified by policy and account for applicable obligations. 13. IANA Considerations This document requests no IANA actions. Jacobs Expires 16 March 2027 [Page 4] Internet-Draft Web4 Evidence Receipts September 2026 14. 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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 15. Informative References [I-D.reilly-web4] Reilly, L. J., "Web4: A Verifiable, Agent-Native Architecture for the World Wide Web", Work in Progress, Internet-Draft, draft-reilly-web4-00, 26 August 2026, . Author's Address Tim Jacobs KTS Global United Arab Emirates Email: tim@ktsglobal.live Jacobs Expires 16 March 2027 [Page 5]