COSE WG C. Lemmons Internet-Draft Comcast Intended status: Standards Track 17 February 2026 Expires: 21 August 2026 Composite Token Claims draft-lemmons-cose-composite-claims-02 Abstract Composition claims are claims for CBOR Web Tokens (CWTs) and JSON Web Tokens (JWTs) that define logical relationships between sets of claims. 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 21 August 2026. Copyright Notice Copyright (c) 2026 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights 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. Lemmons Expires 21 August 2026 [Page 1] Internet-Draft Composite Token Claims February 2026 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Logical Claims . . . . . . . . . . . . . . . . . . . . . 3 3.1.1. or (Or) Claim . . . . . . . . . . . . . . . . . . . . 3 3.1.2. nor (Not Or) Claim . . . . . . . . . . . . . . . . . 4 3.1.3. and (And) Claim . . . . . . . . . . . . . . . . . . . 4 3.1.4. Examples . . . . . . . . . . . . . . . . . . . . . . 5 3.2. crit (Critical) Claim . . . . . . . . . . . . . . . . . . 7 3.2.1. Example . . . . . . . . . . . . . . . . . . . . . . . 8 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.1. Normative References . . . . . . . . . . . . . . . . . . 9 6.2. Informative References . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction Composition claims are claims defined for CBOR Web Tokens (CWTs) [RFC8392] and JSON Web Tokens (JWTs) [RFC7519]. This document defines the CWT representations of the composition claims named "and", "or", "nor". It also defines a CWT definition for "crit". 2. 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. This document reuses terminology from CWT [RFC8392], JWT [RFC7519], and COSE [RFC9052]. This term is defined by this specification: Composition Claim A claim whose value contains one or more claim sets. Claim Set A set of claims. For CWTs this is a CBOR map. For JWTs this is a JSON object. Lemmons Expires 21 August 2026 [Page 2] Internet-Draft Composite Token Claims February 2026 3. Claims Composition claims contain one or more claim sets. In tokens without composition claims, there is exactly one set of claims, so the acceptability of the claim set decides the acceptability of the token. However, this document defines multiple claim sets, so it instead refers to accepting or rejecting claim sets. If the primary claim set is unacceptable, the token is unacceptable and MUST be rejected. Some applications use tokens to convey information. For example, a token might simply have a subject claim that identifies the bearer and the relying party simply uses that as information, not necessarily as a means by which to provide or deny access or make some other kind of decision. In this context, the token simply describes all situations in which the token would accurately describe that situation. Composition claims may be nested arbitrarily. Implementations MAY reject tokens exceeding an implementation-defined nesting depth but MUST support at least four levels. 3.1. Logical Claims These claims identify one or more sets of claims in a logical relation. The type of these claims is array and the elements of the array are maps that are themselves sets of claims. In CWTs, the value is a CBOR array of CBOR maps. In JWTs, the value is a JSON array of JSON objects. For the following CDDL, Claims-Set is a map of claims as defined in [RFC8392]. It is described informatively in [RFC9711], Appendix D. 3.1.1. or (Or) Claim The "or" (Or) claim identifies one or more claim sets of which at least one is acceptable. If none of the claim sets in an "or" claim is acceptable, the claim set containing the "or" claim is also unacceptable. Use of this claim is OPTIONAL. In JWTs, the Claim Name is "or" and the Claim Value is a JSON array of JSON objects. Lemmons Expires 21 August 2026 [Page 3] Internet-Draft Composite Token Claims February 2026 In CWTs, the Claim Key is TBD (to be registered in the "CBOR Web Token (CWT) Claims" registry). The "or" (Or) claim is described by the following CDDL: $$Claims-Set-Claims //= ( or-claim-label => or-claim-value ) or-claim-label = TBD or-claim-value = [ + Claims-Set ] 3.1.2. nor (Not Or) Claim The "nor" (Nor) claim identifies one or more claim sets of which none are acceptable. If any claim set in a "nor" claim is acceptable, the claim set containing the "nor" claim is also unacceptable. This is the logical negation of the "or" claim. Use of this claim is OPTIONAL. In JWTs, the Claim Name is "nor" and the Claim Value is a JSON array of JSON objects. In CWTs, the Claim Key is TBD (to be registered in the "CBOR Web Token (CWT) Claims" registry). The "nor" (Nor) claim is described by the following CDDL: $$Claims-Set-Claims //= ( nor-claim-label => nor-claim-value ) nor-claim-label = TBD nor-claim-value = [ + Claims-Set ] 3.1.3. and (And) Claim The "and" (And) claim identifies one or more claim sets of which all are acceptable. If any claim set in an "and" claim is not acceptable, the claim set containing the "and" claim is also unacceptable. The "and" claim is often unnecessary because a claim set is only accepted when all its claims are acceptable. However, CBOR maps cannot have duplicate keys, so claims cannot be repeated. The "and" claim is useful when a claim needs to appear multiple times, like when using the "or" and "nor" claims. Use of this claim is OPTIONAL. In JWTs, the Claim Name is "and" and the Claim Value is a JSON array of JSON objects. Lemmons Expires 21 August 2026 [Page 4] Internet-Draft Composite Token Claims February 2026 In CWTs, the Claim Key is TBD (to be registered in the "CBOR Web Token (CWT) Claims" registry). The "and" (And) claim is described by the following CDDL: $$Claims-Set-Claims //= ( and-claim-label => and-claim-value ) and-claim-label = TBD and-claim-value = [ + Claims-Set ] 3.1.4. Examples These logical claims can be used to describe more complex relationships between claims. For example, the following claim set describes a token with multiple subject claims. This token describes a situation where either of the two subjects must be true, but the issuer is not disclosing which one must be true or even whether the two subjects are genuinely different. { /or/ TBD: [ { /sub/ 2: "george@example.net" }, { /sub/ 2: "harriet@example.net" } ] } A relying party that receives this token knows that bearer claims to be both George and Harriet and if either subject is acceptable, the token is acceptable. The following JWT claim set example is equivalent: { "or": [ { "sub": "george@example.net" }, { "sub": "harriet@example.net" } ] } The "nor" claim is useful both as a logical negation, even when only one claim is present. For example, consider the following claim set: { /nor/ TBD: [ { /aud/ 3: "https://example.com" } ] } This token is intended for any audience except "example.com". Lemmons Expires 21 August 2026 [Page 5] Internet-Draft Composite Token Claims February 2026 The following JWT claim set example is equivalent: { "nor": [ { "aud": "https://example.com" } ] } Complex relationships can also be described using the claims in combination. The "geohash" claim [CTA5009A] describes a geographical region. For example: { /aud/ 3: "https://example.com", /geohash/ 282: "9q8yy", /nor/ TBD: [ { /geohash/ 282: ["9q8yy9", "9q8yyd"] } ] } This token describes an audience of "https://example.com" (https://example.com") and a region described by the geohash of "9q8yy" that does not include the region described by "9q8yy9" or "9q8yyd". And if a very complex relationship is required, the "and" claim can be used to combine multiple claims. For example, consider the following claim set: { /and/ TBD: [ { /or/ TBD: [ { /sub/ 2: "george@example.net" }, { /sub/ 2: "harriet@example.net" } ] }, { /or/ TBD: [ { /aud/ 3: "https://example.com" }, { /aud/ 3: "https://example.net" } ] } ] } Lemmons Expires 21 August 2026 [Page 6] Internet-Draft Composite Token Claims February 2026 This admittedly contrived example describes a token that is valid for both George and Harriet and is intended for both https://example.com (https://example.com) and https://example.net (https://example.net). It is a bit contrived because the "aud" claim already describes a list of acceptable audiences. The use of the "and" claim is required in order to effectively repeat the "or" claim, because a single claim set cannot contain the same claim twice. 3.2. crit (Critical) Claim The "crit" (Critical) claim indicates critical extensions to this kind of claim set. The semantics of the JWT claim name "crit" are defined by OpenID Federation 1.0 [OpenID-Federation]. This specification defines only the CWT representation. The value of this claim is an array. Each element identifies a claim within the same claim set. In CWTs, elements are integers or text strings identifying claim keys. The "crit" array MUST NOT be empty. Each element of the "crit" array MUST identify a claim that is present in the same claim set. Elements in the "crit" array MUST be unique. Elements in the "crit" array MUST NOT identify claims that are specified as MANDATORY to understand for the token. This will vary by application profile as described in [RFC7519], Section 4. As noted in [OpenID-Federation], Section 13.4, any profile that requires correct processing of the "crit" claim MUST of necessity specify that it is MANDATORY to understand. If a claim listed in the "crit" claim is present in a claim set and the processor cannot process the claim for any reason, the claim set MUST be rejected. If a claim listed in the "crit" claim is not present in a claim set, the claim set MUST be rejected. (TODO: Square this with the OpenID definition. The OpenID definition does not explicitly require claim sets to be rejected if the claim name rules like including duplicates, empty arrays, or the presence of claims that are not present in the claim set.) Use of this claim is OPTIONAL. In CWTs, the Claim Key is TBD (to be registered in the "CBOR Web Token (CWT) Claims" registry). Lemmons Expires 21 August 2026 [Page 7] Internet-Draft Composite Token Claims February 2026 3.2.1. Example A "crit" claim can be used in conjunction with logical claims to condition a portion of the token on the ability to process a claim: { /or/ TBD: [ { /geohash/ 282: "9q8y", /crit/ TBD: [ 282 ] }, { /private/ -524289: "sf", /crit/ TBD: [ -524289 ] } ] } This example assumes the existence of some kind of claim in the private space that a relying party may or may not be able to process. This token claims that the subject is in the described region and also that a private claim is present and that the relying party must be able to verify at least one of those claims, but it does not need to be able to process both. 4. Security Considerations All security considerations relevant to CWTs and JWTs in general will apply to tokens that use composition claims. Additionally, processors of tokens with composition claims will need to be aware of the possibility of receiving highly nested tokens. Excessive nesting can lead to overflows or other processing errors. 5. IANA Considerations This specification requests that IANA register the following claim keys in the "CBOR Web Token (CWT) Claims" registry established by [RFC8392]: Claim Name: or Claim Description: Logical OR JWT Claim Name: or Claim Key: TBD Claim Value Type(s): array Change Controller: IESG Claim Name: nor Claim Description: Logical NOR JWT Claim Name: nor Claim Key: TBD Claim Value Type(s): array Change Controller: IESG Lemmons Expires 21 August 2026 [Page 8] Internet-Draft Composite Token Claims February 2026 Claim Name: and Claim Description: Logical AND JWT Claim Name: and Claim Key: TBD Claim Value Type(s): array Change Controller: IESG Claim Name: crit Claim Description: Critical Claims JWT Claim Name: crit Claim Key: TBD Claim Value Type(s): array Change Controller: IESG This specification requests that IANA register the following claim names in the "JSON Web Token Claims" registry established by [RFC7519]: Claim Name: or Claim Description: Logical OR Change Controller: IESG Specification Document(s): This document Claim Name: nor Claim Description: Logical NOR Change Controller: IESG Specification Document(s): This document Claim Name: and Claim Description: Logical AND Change Controller: IESG Specification Document(s): This document The JWT Claim Name "crit" is already registered in the "JSON Web Token Claims" registry and is defined by OpenID Federation 1.0 [OpenID-Federation]. 6. References 6.1. Normative References [OpenID-Federation] OpenID Foundation, "OpenID Federation 1.0", . Lemmons Expires 21 August 2026 [Page 9] Internet-Draft Composite Token Claims February 2026 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, May 2018, . [RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE): Structures and Process", STD 96, RFC 9052, DOI 10.17487/RFC9052, August 2022, . 6.2. Informative References [CTA5009A] Consumer Technology Association, "CTA 5009-A: Fast and Readable Geographical Hashing", 2024, . [RFC9711] Lundblade, L., Mandyam, G., O'Donoghue, J., and C. Wallace, "The Entity Attestation Token (EAT)", RFC 9711, DOI 10.17487/RFC9711, April 2025, . Author's Address Chris Lemmons Comcast Email: chris_lemmons@comcast.com Lemmons Expires 21 August 2026 [Page 10]