CoRE Working group C. Bormann Internet-Draft Universität Bremen TZI Intended status: Informational 6 November 2022 Expires: 10 May 2023 CoRE Target Attribute Registry draft-bormann-core-target-attr-01 Abstract The Constrained RESTful Environments (CoRE) specifications apply Web technologies to constrained environments. One important such technology is Web Linking [RFC8288], which CoRE uses as the basis for a number of discovery protocols, such as the Link Format [RFC6690] in CoAP's Resource Discovery Protocol (Section 7 of [RFC7252]) and the Resource Directory [RFC9176]. Web Links can have Target Attributes, the names of which are not generally coordinated by the Web Linking specification (Section 2.2 of [RFC8288]). This short note introduces an IANA registry for coordinating names of Target Attributes when used in Constrained RESTful Environments. About This Document This note is to be removed before publishing as an RFC. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-bormann-core-target-attr/. Discussion of this document takes place on the core Working Group mailing list (mailto:core@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/core/. Subscribe at https://www.ietf.org/mailman/listinfo/core/. Source for this draft and an issue tracker can be found at https://github.com/cabo/core-target-attr. 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/. Bormann Expires 10 May 2023 [Page 1] Internet-Draft CoRE Target Attribute Registry November 2022 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 10 May 2023. Copyright Notice Copyright (c) 2022 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 3. Security considerations . . . . . . . . . . . . . . . . . . . 8 4. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Normative References . . . . . . . . . . . . . . . . . . 8 4.2. Informative References . . . . . . . . . . . . . . . . . 9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction (Please see abstract.) The original Web Linking specification Section 3 of [RFC5988] did not attempt to coordinate names of target attributes except for providing common target attributes for use in the Link HTTP header. The current revision of that specification clarifies (Section 2.2 of [RFC8288]): Bormann Expires 10 May 2023 [Page 2] Internet-Draft CoRE Target Attribute Registry November 2022 | This specification does not attempt to coordinate the name of | target attributes, their cardinality, or use. Those creating and | maintaining serialisations SHOULD coordinate their target | attributes to avoid conflicts in semantics or syntax and MAY | define their own registries of target attributes. This short note introduces an IANA registry for coordinating names of Target Attributes when used in Constrained RESTful Environments. With a registry now available, registration of target attributes is strongly encouraged. The incentive is that an unregistered attribute name might be registered with a different meaning at any time. (See also Section 2, Paragraph 2.) 1.1. 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. IANA Considerations This specification defines a new sub-registry for Target Attributes in the CoRE Parameters registry [IANA.core-parameters], with the policy "expert review" (Section 4.5 of [BCP26]). The expert is instructed to be frugal in the allocation of very short target attribute names, keeping them in reserve for applications that are likely to enjoy wide use and can make good use of their shortness. The expert is also instructed to direct the registrant to provide a specification (Section 4.6 of [BCP26]), but can make exceptions, for instance when a specification is not available at the time of registration but is likely forthcoming. If the expert becomes aware of target attributes that are deployed and in use, they may also initiate a registration on their own if they deem such a registration can avert potential future collisions. Each entry in the registry must include: Attribute Name: a lower case ASCII [STD90] string that starts with a letter and can contain digits and hyphen-minus characters afterwards ([a-z][-a-z0-9]*). (Note that [RFC8288] requires target attribute names to be interpreted in a case-insensitive way; the restriction to lower case here ensures that they are registered in a predictable form). Bormann Expires 10 May 2023 [Page 3] Internet-Draft CoRE Target Attribute Registry November 2022 Brief description: a brief description Change Controller: (see Section 2.3 of [BCP26]) Reference: a reference document that provides a description of the target attribute, including the semantics for when the target attribute appears more than once in a link. Initial entries in this sub-registry are as listed in Table 1: +===============+==============+==========+==================================+ |Attribute Name |Brief |Change |Reference | | |description |Controller| | +===============+==============+==========+==================================+ |href |reserved (not |IESG |[RFC6690] | | |useful as | | | | |target | | | | |attribute | | | | |name) | | | +---------------+--------------+----------+----------------------------------+ |anchor |reserved (not |IESG |[RFC6690] | | |useful as | | | | |target | | | | |attribute | | | | |name) | | | +---------------+--------------+----------+----------------------------------+ |rel |reserved (not |IESG |[RFC6690] | | |useful as | | | | |target | | | | |attribute | | | | |name) | | | +---------------+--------------+----------+----------------------------------+ |rev |reserved (not |IESG |[RFC6690] | | |useful as | | | | |target | | | | |attribute | | | | |name) | | | +---------------+--------------+----------+----------------------------------+ |hreflang |(Web Linking) |IESG |[RFC8288] | +---------------+--------------+----------+----------------------------------+ |media |(Web Linking) |IESG |[RFC8288] | +---------------+--------------+----------+----------------------------------+ |title |(Web Linking) |IESG |[RFC8288] | +---------------+--------------+----------+----------------------------------+ |type |(Web Linking) |IESG |[RFC8288] | Bormann Expires 10 May 2023 [Page 4] Internet-Draft CoRE Target Attribute Registry November 2022 +---------------+--------------+----------+----------------------------------+ |rt |resource type |IESG |Section 3.1 of [RFC6690] | +---------------+--------------+----------+----------------------------------+ |if |interface |IESG |Section 3.2 of [RFC6690] | | |description | | | +---------------+--------------+----------+----------------------------------+ |sz |maximum size |IESG |Section 3.3 of [RFC6690] | | |estimate | | | +---------------+--------------+----------+----------------------------------+ |ct |Content-Format|IESG |Section 7.2.1 of [RFC7252] | | |hint | | | +---------------+--------------+----------+----------------------------------+ |obs |observable |IESG |Section 6 of [RFC7641] | | |resource | | | +---------------+--------------+----------+----------------------------------+ |hct |HTTP-CoAP URI |IESG |Section 5 of [RFC8075] | | |mapping | | | | |template | | | +---------------+--------------+----------+----------------------------------+ |osc |hint: resource|IESG |Section 9 of [RFC8613] | | |only | | | | |accessible | | | | |using OSCORE | | | +---------------+--------------+----------+----------------------------------+ |method |A supported |IESG |Section 6 of | | |authentication| |[I-D.ietf-core-oscore-edhoc] | | |method for | | | | |EDHOC | | | +---------------+--------------+----------+----------------------------------+ |csuite |A supported |IESG |Section 6 of | | |cipher suite | |[I-D.ietf-core-oscore-edhoc] | | |for EDHOC | | | +---------------+--------------+----------+----------------------------------+ |cred_t |A supported |IESG |Section 6 of | | |type of | |[I-D.ietf-core-oscore-edhoc] | | |authentication| | | | |credential for| | | | |EDHOC | | | +---------------+--------------+----------+----------------------------------+ |idcred_t |A supported |IESG |Section 6 of | | |type of | |[I-D.ietf-core-oscore-edhoc] | | |authentication| | | | |credential | | | | |identifier for| | | | |EDHOC | | | +---------------+--------------+----------+----------------------------------+ |ead_1 |A supported |IESG |Section 6 of | | |EDHOC EAD_1 | |[I-D.ietf-core-oscore-edhoc] | Bormann Expires 10 May 2023 [Page 5] Internet-Draft CoRE Target Attribute Registry November 2022 | |item | | | +---------------+--------------+----------+----------------------------------+ |ead_2 |A supported |IESG |Section 6 of | | |EDHOC EAD_2 | |[I-D.ietf-core-oscore-edhoc] | | |item | | | +---------------+--------------+----------+----------------------------------+ |ead_3 |A supported |IESG |Section 6 of | | |EDHOC EAD_3 | |[I-D.ietf-core-oscore-edhoc] | | |item | | | +---------------+--------------+----------+----------------------------------+ |ead_4 |A supported |IESG |Section 6 of | | |EDHOC EAD_4 | |[I-D.ietf-core-oscore-edhoc] | | |item | | | +---------------+--------------+----------+----------------------------------+ |comb_req |Hint: support |IESG |Section 6 of | | |for the | |[I-D.ietf-core-oscore-edhoc] | | |EDHOC+OSCORE | | | | |request | | | +---------------+--------------+----------+----------------------------------+ |sec-gp |Name of the |IESG |Section 2.1 of | | |security group| |[I-D.tiloca-core-oscore-discovery]| | |that can be | | | | |joined through| | | | |this resource | | | +---------------+--------------+----------+----------------------------------+ |app-gp |Name of an |IESG |Section 2.1 of | | |application | |[I-D.tiloca-core-oscore-discovery]| | |group | | | | |associated | | | | |with a | | | | |security group| | | +---------------+--------------+----------+----------------------------------+ |hkdf |The HKDF |IESG |Section 2.1 of | | |algorithm to | |[I-D.tiloca-core-oscore-discovery]| | |use | | | +---------------+--------------+----------+----------------------------------+ |cred_fmt |The format of |IESG |Section 2.1 of | | |authentication| |[I-D.tiloca-core-oscore-discovery]| | |credential to | | | | |use | | | +---------------+--------------+----------+----------------------------------+ |sign_enc_alg |The encryption|IESG |Section 2.1 of | | |algorithm to | |[I-D.tiloca-core-oscore-discovery]| | |use for | | | | |encrypting | | | | |signed | | | | |messages | | | +---------------+--------------+----------+----------------------------------+ Bormann Expires 10 May 2023 [Page 6] Internet-Draft CoRE Target Attribute Registry November 2022 |sign_alg |The signature |IESG |Section 2.1 of | | |algorithm to | |[I-D.tiloca-core-oscore-discovery]| | |use | | | +---------------+--------------+----------+----------------------------------+ |sign_alg_crv |The elliptic |IESG |Section 2.1 of | | |curve of the | |[I-D.tiloca-core-oscore-discovery]| | |used signature| | | | |algorithm | | | +---------------+--------------+----------+----------------------------------+ |sign_key_kty |The key type |IESG |Section 2.1 of | | |of the used | |[I-D.tiloca-core-oscore-discovery]| | |signing keys | | | +---------------+--------------+----------+----------------------------------+ |sign_key_crv |The curve of |IESG |Section 2.1 of | | |the used | |[I-D.tiloca-core-oscore-discovery]| | |signing keys | | | +---------------+--------------+----------+----------------------------------+ |alg |The encryption|IESG |Section 2.1 of | | |algorithm to | |[I-D.tiloca-core-oscore-discovery]| | |use for | | | | |encrypting | | | | |non-signed | | | | |messages | | | +---------------+--------------+----------+----------------------------------+ |ecdh_alg |The ECDH |IESG |Section 2.1 of | | |algorithm to | |[I-D.tiloca-core-oscore-discovery]| | |use | | | +---------------+--------------+----------+----------------------------------+ |ecdh_alg_crv |The elliptic |IESG |Section 2.1 of | | |curve of the | |[I-D.tiloca-core-oscore-discovery]| | |used ECDH | | | | |algorithm | | | +---------------+--------------+----------+----------------------------------+ |ecdh_key_kty |The key type |IESG |Section 2.1 of | | |of the used | |[I-D.tiloca-core-oscore-discovery]| | |ECDH keys | | | +---------------+--------------+----------+----------------------------------+ |ecdh_key_crv |The curve of |IESG |Section 2.1 of | | |the used ECDH | |[I-D.tiloca-core-oscore-discovery]| | |keys | | | +---------------+--------------+----------+----------------------------------+ |det_hash_alg |The hash |IESG |Section 2.1 of | | |algorithm to | |[I-D.tiloca-core-oscore-discovery]| | |use for | | | | |computing | | | | |deterministic | | | | |requests | | | +---------------+--------------+----------+----------------------------------+ Bormann Expires 10 May 2023 [Page 7] Internet-Draft CoRE Target Attribute Registry November 2022 |rekeying_scheme|The rekeying |IESG |Section 2.1 of | | |scheme used to| |[I-D.tiloca-core-oscore-discovery]| | |distribute new| | | | |keying | | | | |material | | | +---------------+--------------+----------+----------------------------------+ Table 1: Initial Entries in the Target Attributes Registry A number of names are reserved as they are used for parameters in links other than target attributes, a further set is predefined in [RFC8288]. 3. Security considerations The security considerations of [RFC8288] apply, as do those of the discovery specifications [RFC6690], [RFC7252], and [RFC9176]. 4. References 4.1. Normative References [BCP26] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [IANA.core-parameters] IANA, "Constrained RESTful Environments (CoRE) Parameters", 8 June 2012, . [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, . [RFC8288] Nottingham, M., "Web Linking", RFC 8288, DOI 10.17487/RFC8288, October 2017, . [STD90] Cerf, V., "ASCII format for network interchange", STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969, . Bormann Expires 10 May 2023 [Page 8] Internet-Draft CoRE Target Attribute Registry November 2022 4.2. Informative References [I-D.ietf-core-oscore-edhoc] Palombini, F., Tiloca, M., Höglund, R., Hristozov, S., and G. Selander, "Profiling EDHOC for CoAP and OSCORE", Work in Progress, Internet-Draft, draft-ietf-core-oscore-edhoc- 05, 24 October 2022, . [I-D.tiloca-core-oscore-discovery] Tiloca, M., Amsüss, C., and P. Van der Stok, "Discovery of OSCORE Groups with the CoRE Resource Directory", Work in Progress, Internet-Draft, draft-tiloca-core-oscore- discovery-12, 5 September 2022, . [RFC5988] Nottingham, M., "Web Linking", RFC 5988, DOI 10.17487/RFC5988, October 2010, . [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link Format", RFC 6690, DOI 10.17487/RFC6690, August 2012, . [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, June 2014, . [RFC7641] Hartke, K., "Observing Resources in the Constrained Application Protocol (CoAP)", RFC 7641, DOI 10.17487/RFC7641, September 2015, . [RFC8075] Castellani, A., Loreto, S., Rahman, A., Fossati, T., and E. Dijk, "Guidelines for Mapping Implementations: HTTP to the Constrained Application Protocol (CoAP)", RFC 8075, DOI 10.17487/RFC8075, February 2017, . [RFC8613] Selander, G., Mattsson, J., Palombini, F., and L. Seitz, "Object Security for Constrained RESTful Environments (OSCORE)", RFC 8613, DOI 10.17487/RFC8613, July 2019, . Bormann Expires 10 May 2023 [Page 9] Internet-Draft CoRE Target Attribute Registry November 2022 [RFC9176] Amsüss, C., Ed., Shelby, Z., Koster, M., Bormann, C., and P. van der Stok, "Constrained RESTful Environments (CoRE) Resource Directory", RFC 9176, DOI 10.17487/RFC9176, April 2022, . Acknowledgements TBD Contributors Jaime Jiménez Ericsson Email: jaime@iki.fi Jaime provided the list of initial registrations. Author's Address Carsten Bormann Universität Bremen TZI Postfach 330440 D-28359 Bremen Germany Phone: +49-421-218-63921 Email: cabo@tzi.org Bormann Expires 10 May 2023 [Page 10]