Network Working Group Wallace Internet-Draft LicenseFoundry Intended status: Standards Track 6 August 2026 Expires: 7 February 2027 A Verifiable-Credential Binding for AI Usage Preferences: Expressing Grants that Lift AIPREF Preferences draft-wallace-aipref-grant-binding-01 Abstract The AI Preferences (AIPREF) vocabulary lets those with rights in a digital asset express preferences -- for example, that training of AI models is disallowed -- about how automated systems process that asset. Such a preference expresses a reservation. It does not, by itself, provide a verifiable, revocable record of a specific grant that lifts a preference for a specific party. This document describes that gap and proposes a candidate mechanism: a cryptographically signed, offline-verifiable credential that expresses a grant referencing an AIPREF usage category and a specific asset, that any party can verify without contacting the grantor, and that the grantor can revoke. It is intended as a starting point for discussion, not as a finished specification. 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 7 February 2027. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. Wallace Expires 7 February 2027 [Page 1] Internet-Draft AIPREF Grant Binding August 2026 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Relationship to the AIPREF Vocabulary . . . . . . . . . . . . 4 3. Relationship to Bilateral Contracts . . . . . . . . . . . . . 4 4. The Grant Credential . . . . . . . . . . . . . . . . . . . . 5 4.1. Structure . . . . . . . . . . . . . . . . . . . . . . . . 5 4.2. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Verification Procedure . . . . . . . . . . . . . . . . . . . 6 6. Revocation . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1. As-of-Use Evaluation . . . . . . . . . . . . . . . . . . 7 7. Discussion and Open Questions . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 10. Normative References . . . . . . . . . . . . . . . . . . . . 9 11. Informative References . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction The AI Preferences vocabulary [AIPREF-VOCAB] defines a machine- readable way to express preferences about how automated systems process a digital asset. Each usage category (for example, "train- ai") is assigned a value such as "allowed" or "disallowed". A preference of "train-ai=disallowed" is a standing statement of intent by a party with rights in the asset: a reservation. Preferences describe a default posture toward the world. They do not express what a _specific_ party has been permitted to do. When a rights holder does permit a specific use by a specific party -- under a license, a negotiated agreement, or otherwise -- there is at present no interoperable, verifiable way to express and check that grant. This produces three operational problems: * a party acting on a permission cannot _prove_, to a third party, that it held that permission for a given asset on a given date; Wallace Expires 7 February 2027 [Page 2] Internet-Draft AIPREF Grant Binding August 2026 * a rights holder that granted a permission cannot _withdraw_ it in a way that downstream verifiers can observe; and * a dispute over whether an asset was permitted for a use cannot be resolved on independently checkable evidence. Informally: an AIPREF preference is the lock; what is missing is a verifiable key, and a receipt for it that survives inspection later. This document sketches that missing piece as a signed, revocable credential that sits _on top of_ the AIPREF vocabulary rather than replacing it, and asks where such a mechanism belongs. This document does not propose changes to the AIPREF vocabulary itself, nor does it assert that a preference is legally binding or that any particular use is or is not permitted absent a grant. Those questions are out of scope. 1.1. 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. 1.2. Terminology Preference: An AIPREF value (e.g. "allowed"/"disallowed") assigned to a usage category for an asset, per [AIPREF-VOCAB]. Grant: A statement that a named party is permitted a specific usage category for a specific asset, over a validity period, expressed as the credential defined in Section 4. Grantor: The party that issues (signs) a grant. Typically the rights holder or an authorised issuer acting on the rights holder's behalf. Grantee: The party a grant names as permitted. Verifier: Any party that checks a grant -- for example an AI system, an auditor, a court, or a counterparty. Wallace Expires 7 February 2027 [Page 3] Internet-Draft AIPREF Grant Binding August 2026 2. Relationship to the AIPREF Vocabulary A grant references an AIPREF usage category by its label (for example "train-ai" from [AIPREF-VOCAB], or a category introduced through that document's vocabulary-extension mechanism). A grant is scoped to a tuple of (asset, category, grantee, validity period). A grant that asserts "allowed" for a category lifts a "disallowed" preference for that category _for the named grantee only_; it makes no statement about any other party. Grants and preferences are therefore complementary layers. The preference is authored by the rights holder as a standing signal; the grant is a discrete, verifiable exception issued to a specific party. A verifier that observes both applies the grant in preference to the standing preference for the named grantee, and applies the standing preference otherwise. This document does not require AIPREF to define any new category to carry grants. It observes only that a category value MAY be lifted, for a named grantee, by a grant that the grantee can present and any verifier can check. Preferences and grants also differ in how they are distributed. AIPREF preferences are typically attached to content and expressed to the world -- for example through robots.txt or HTTP header fields -- as a broadcast, party-agnostic signal of a default posture. A grant is not distributed that way: it is a signed artifact bound to a named grantee, held and presented by that grantee (or retrieved by reference), and checkable by any verifier without being attached to the content or announced to the world. A grant therefore complements a content-attached preference rather than competing with it: the preference is the broadcast reservation; the grant is the verifiable, per-party exception. 3. Relationship to Bilateral Contracts A grant is a unilateral artifact: it is signed by the grantor alone. A separate class of mechanism expresses a _bilateral_ agreement -- an offer made and accepted, signed by both parties. VDAC [VDAC] is one such mechanism. Grants and bilateral contracts are complementary layers, and they compose: a contract MAY carry a grant as one of its terms. A contract carries a grant by reference. It names the grant with a type token -- for example "verifiable-grant" -- whose meaning is the resolution-and-verification procedure of Section 5; it identifies the grant by the grant's resolvable identifier (Section 4.1); and it pins the specific artifact by a cryptographic digest of the credential as Wallace Expires 7 February 2027 [Page 4] Internet-Draft AIPREF Grant Binding August 2026 retrieved, expressed using the Digest Fields representation [RFC9530]. The contract layer establishes _which_ document is carried; this document establishes _whether_ it is valid, and as of when. The contract does not interpret the grant beyond resolving and hashing it; a receiver that can process a carried grant reference verifies it per Section 5, including revocation under the as-of-use rule (Section 6.1). Revocation composes across the two layers without conflict. A bilateral contract, once signed, is an immutable record that an agreement was reached; revoking a grant carried within it does not un-sign the contract. The grant's own status list carries the revocation, which the contract references. A grant marked revoked is void from the time of revocation forward, while the fact that the contract was agreed remains true. The two layers answer different questions -- what was agreed, and whether a carried grant still applies -- and both remain independently checkable. 4. The Grant Credential 4.1. Structure A grant is expressed as a Verifiable Credential [VC-DATA-MODEL], secured as a JSON Web Signature per [VC-JOSE-COSE], with the JWS header parameters "typ: vc+jwt" and "cty: vc". It carries at least: * a resolvable *identifier* for the grant itself, so that a party holding a reference to the grant -- for example a contract that carries it (Section 3) -- can retrieve the credential; typically an HTTPS URL; * an *issuer* identifier that a verifier can resolve to a public key -- for example a "did:web" [DID-WEB] identifier resolvable over HTTPS; * the *asset* the grant concerns, identified by a cryptographic content digest (e.g. SHA-256) so the grant binds to specific content without carrying the content itself; * the *grantee* the grant names; * one or more *usage* entries, each naming an AIPREF category and the granted value (e.g. "train-ai" = "allowed"); * a *validity period* (validFrom / validUntil); and * a *revocation* reference, such as a Bitstring Status List [BITSTRING] entry, that a verifier can check. Wallace Expires 7 February 2027 [Page 5] Internet-Draft AIPREF Grant Binding August 2026 A grant MUST be signed by the grantor's key. A grant MUST identify the asset by content digest. A grant SHOULD carry a revocation reference; a grant without one cannot be withdrawn after issuance. 4.2. Example The following is the (unsecured) JSON [RFC8259] payload of a grant that permits "train-ai" of a specific asset to a named grantee for one year. In transit it is secured as a JWS per [VC-JOSE-COSE]. { "@context": ["https://www.w3.org/ns/credentials/v2"], "id": "https://publisher.example/grants/abc123", "type": ["VerifiableCredential", "AIUsageGrantCredential"], "issuer": "did:web:publisher.example", "validFrom": "2026-07-01T00:00:00Z", "validUntil": "2027-07-01T00:00:00Z", "credentialSubject": { "asset": { "id": "urn:asset:sha-256", "digest": "sha-256:0f7e...c19a" }, "grantee": "did:web:ai-lab.example", "usage": [ { "category": "train-ai", "value": "allowed" } ] }, "credentialStatus": { "type": "BitstringStatusListEntry", "statusPurpose": "revocation", "statusListIndex": "94", "statusListCredential": "https://publisher.example/status/1" } } The "category" value ("train-ai") is an AIPREF category [AIPREF-VOCAB]. The "value" ("allowed") lifts a "disallowed" preference for that category, for the named grantee, over the validity period, unless the grant has been revoked. 5. Verification Procedure To act on a grant, a verifier: 1. resolves the issuer identifier to a public key (for "did:web", by fetching the DID document over HTTPS [DID-WEB]) and verifies the signature over the credential; Wallace Expires 7 February 2027 [Page 6] Internet-Draft AIPREF Grant Binding August 2026 2. confirms the current time is within the validity period; 3. confirms the grant was not revoked as of the relevant time, by checking the referenced status list [BITSTRING] under the as-of- use rule (Section 6.1); 4. confirms the asset digest matches the content in question, and that the category and grantee match the use and party at hand. If all checks pass, a valid grant exists for that (asset, category, grantee); the corresponding preference is lifted for that grantee. Verification requires no interaction with the grantor beyond fetching the (cacheable) issuer key and status list, and can be performed offline against cached copies. 6. Revocation A grantor withdraws a grant by updating the referenced status list so that the grant's entry indicates revocation. Verifiers observe the change the next time they refresh the status list, bounded by their cache policy. Revocation lets a rights holder end a permission after issuance -- a property that a standing preference change alone cannot provide for permissions already relied upon. Revocation is monotonic: a status list using the "revocation" status purpose [BITSTRING] only ever moves a grant's entry from valid to revoked, never back. 6.1. As-of-Use Evaluation The relevant time for a revocation check depends on the question being asked. A verifier deciding whether to act on a grant now checks the current status list: the question is whether the grant is revoked at present. A verifier instead evaluating a _past_ use -- for example an auditor asking whether a use was permitted at the time it occurred -- asks a different question, and the relevant time is the time of that use, not the present. Because a grant may be validly relied upon and only later revoked, checking a past use against the _current_ status list would incorrectly report the use as unpermitted whenever the grant was revoked after the use. A verifier evaluating a past use therefore checks revocation status _as of the time of use_. This is the as-of- use rule. As-of-use evaluation is supported by an issuer-signed snapshot of the status list whose signed validity time covers the time of use. The snapshot establishes the revocation state that was in force at that time, independently of the current list. Because revocation is Wallace Expires 7 February 2027 [Page 7] Internet-Draft AIPREF Grant Binding August 2026 monotonic (Section 6), a snapshot taken at or after the time of use is sufficient to establish that a grant was not revoked as of that time. 7. Discussion and Open Questions This document is a discussion starter. The mechanism in Section 4 is one candidate, not a final design. The author invites discussion of the following in particular: * Venue. The AI Preferences Working Group has, to date, scoped mechanisms above the vocabulary -- attachment, transmission, grants, and identity -- out of its charter. On that reading, grants and related mechanisms are better progressed elsewhere; this document suggests the DISPATCH area as their home, and invites confirmation that this is the right venue. * Should the AIPREF vocabulary define any hook that indicates a category value is conditional on, or may be lifted by, a grant -- or should grants remain entirely a separate layer, as sketched here? * Is a Verifiable Credential the right container, or should a lighter or different encoding be preferred? This document uses VCs because they provide issuer identity, offline verification, and revocation as existing, interoperable building blocks, but does not assert they are the only viable choice. * Grantee identity. A grant names its grantee by a resolvable identifier -- for example a "did:web" identifier. Where a grant is exercised through a bilateral contract (Section 3), binding the presenting party to the named grantee at request time is a function of that contract layer rather than of the grant itself. Whether a grant should additionally carry its own request-time binding is left open. 8. Security Considerations A grant proves who issued it, when, and what was declared. It does _not_ attest that the grantor holds the rights it purports to grant: anyone in possession of an asset can compute its digest and issue a self-asserted grant over it. A verifier therefore MUST evaluate whether it trusts the issuer for the asset in question; the signature establishes the issuer's identity and the integrity of the declaration, not the truth of the underlying claim. Mechanisms for establishing that an issuer is authoritative for an asset are out of scope for this document. Wallace Expires 7 February 2027 [Page 8] Internet-Draft AIPREF Grant Binding August 2026 Because a grant identifies its asset by content digest and does not carry the content, presenting a grant does not disclose the asset. Verifiers MUST confirm the digest matches the content actually processed; a grant for one asset says nothing about another. Revocation is only as timely as verifiers' status-list refresh policy; a verifier relying on a stale cache may act on a revoked grant. Grants SHOULD carry a validity period so that a lost or unreachable status list does not extend a grant indefinitely. 9. IANA Considerations This document has no IANA actions. Should the mechanism advance, a registry for the credential "type" and any grant-specific fields would be considered at that time. 10. Normative References [AIPREF-VOCAB] Keller, P. and M. Thomson, Ed., "A Vocabulary For Expressing AI Usage Preferences", Work in Progress, Internet-Draft, draft-ietf-aipref-vocab, 2026, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, May 2017, . [VC-DATA-MODEL] W3C, "Verifiable Credentials Data Model v2.0", 2025, . [VC-JOSE-COSE] W3C, "Securing Verifiable Credentials using JOSE and COSE", 2025, . 11. Informative References [BITSTRING] W3C, "Bitstring Status List v1.0", 2025, . Wallace Expires 7 February 2027 [Page 9] Internet-Draft AIPREF Grant Binding August 2026 [DID-WEB] W3C Credentials Community Group, "did:web Method Specification", 2025, . [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, December 2017, . [RFC9530] Polli, R. and L. Pardue, "Digest Fields", RFC 9530, February 2024, . [VDAC] Jovancevic, S., "Verifiable Data Access Contract (VDAC)", Work in Progress, Internet-Draft, draft-jovancevic-vdac, 2026, . Author's Address Wallace LicenseFoundry Netherlands Email: wallace@licensefoundry.com Wallace Expires 7 February 2027 [Page 10]