Remote ATtestation ProcedureS T. Fossati Internet-Draft Independent Intended status: Standards Track H. Birkholz Expires: 4 January 2027 Fraunhofer SIT N. Ritz Independent P. Howard Arm 3 July 2026 RATS ReST APIs draft-fossati-rats-rare-00 Abstract This document describes a set of REST APIs that can be used by RATS roles to interact. These APIs facilitate the discovery of a role's capabilities, as well as the negotiation and exchange of RATS Conceptual Messages in several key scenarios, including Evidence gathering, Evidence appraisal, Endorsements and Reference Value management. This document aims to present a useful subset of possible RATS interaction patterns, rather than covering all of them. About This Document This note is to be removed before publishing as an RFC. The latest revision of this draft can be found at https://thomas- fossati.github.io/rare/draft-fossati-rats-rare.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-fossati-rats-rare/. Discussion of this document takes place on the Remote ATtestation ProcedureS Working Group mailing list (mailto:rats@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/rats/. Subscribe at https://www.ietf.org/mailman/listinfo/rats/. Source for this draft and an issue tracker can be found at https://github.com/thomas-fossati/rare. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Fossati, et al. Expires 4 January 2027 [Page 1] Internet-Draft RARE July 2026 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 4 January 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 3. Appraisal . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 3 3.2. Stateless Challenge-Response . . . . . . . . . . . . . . 3 3.3. Stateful Challenge-Response . . . . . . . . . . . . . . . 3 3.3.1. Synchronous Completion . . . . . . . . . . . . . . . 3 3.3.2. Asynchronous Completion . . . . . . . . . . . . . . . 3 4. Endorsements and Reference Values Management . . . . . . . . 3 4.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 3 4.2. RIM Provisioning . . . . . . . . . . . . . . . . . . . . 3 4.3. RIM Retrieval, Activation and Deactivation . . . . . . . 4 4.3.1. The Query Object . . . . . . . . . . . . . . . . . . 4 4.3.2. Activating RIMs . . . . . . . . . . . . . . . . . . . 4 4.3.3. Deactivating RIMs . . . . . . . . . . . . . . . . . . 4 4.3.4. Retrieving RIMs . . . . . . . . . . . . . . . . . . . 4 5. Evidence Collection . . . . . . . . . . . . . . . . . . . . . 4 5.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 4 5.2. Evidence Format for Composite Evidence . . . . . . . . . 4 5.3. Challenge-Response . . . . . . . . . . . . . . . . . . . 4 Fossati, et al. Expires 4 January 2027 [Page 2] Internet-Draft RARE July 2026 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 8. Normative References . . . . . . . . . . . . . . . . . . . . 4 Appendix A. Collated CDDL . . . . . . . . . . . . . . . . . . . 5 A.1. Composite Attestation Token . . . . . . . . . . . . . . . 5 Appendix B. OpenAPI Schema . . . . . . . . . . . . . . . . . . . 7 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction TODO Introduction Section 3 describes APIs for the appraisal of Evidence. Section 4 describes APIs for Endorsements and Reference Values management. Section 5 describes APIs for requesting Evidence from a (composite) Attester, together with a data format for aggregating composite Evidence based on Collection CMWs [I-D.ietf-rats-msg-wrap]. The Evidence appraisal and Evidence request APIs are both based on the challenge-response interaction model described in Section 7.1 of [I-D.ietf-rats-reference-interaction-models]. 2. Conventions and Definitions 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. 3. Appraisal 3.1. Discovery 3.2. Stateless Challenge-Response 3.3. Stateful Challenge-Response 3.3.1. Synchronous Completion 3.3.2. Asynchronous Completion 4. Endorsements and Reference Values Management 4.1. Discovery 4.2. RIM Provisioning Fossati, et al. Expires 4 January 2027 [Page 3] Internet-Draft RARE July 2026 4.3. RIM Retrieval, Activation and Deactivation 4.3.1. The Query Object 4.3.2. Activating RIMs 4.3.3. Deactivating RIMs 4.3.4. Retrieving RIMs 5. Evidence Collection 5.1. Discovery 5.2. Evidence Format for Composite Evidence 5.3. Challenge-Response 6. Security Considerations TODO Security 7. IANA Considerations TODO IANA 8. Normative References [I-D.ietf-rats-msg-wrap] Birkholz, H., Smith, N., Fossati, T., Tschofenig, H., and D. Glaze, "RATS Conceptual Messages Wrapper (CMW)", Work in Progress, Internet-Draft, draft-ietf-rats-msg-wrap-23, 11 December 2025, . [I-D.ietf-rats-reference-interaction-models] Birkholz, H., Eckel, M., Pan, W., and E. Voit, "Reference Interaction Models for Remote Attestation Procedures", Work in Progress, Internet-Draft, draft-ietf-rats- reference-interaction-models-17, 2 April 2026, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Fossati, et al. Expires 4 January 2027 [Page 4] Internet-Draft RARE July 2026 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Appendix A. Collated CDDL A.1. Composite Attestation Token =============== NOTE: '\' line wrapping per RFC 8792 ================ cat-token = #6.18([ protected: bytes .cbor phdrs, unprotected: uhdrs, payload: bytes .cbor cat-collection, signature: bytes, ]) phdrs = { ? &(x5chain: 33) => bytes / [2*certs: bytes], * cose.label => cose.values, } uhdrs = {* cose.label => cose.values} cat-collection = { "__cmwc_t" => RATSD-CMWCT, "__ratsd" => [ RATSD-CLAIMS-MEDIATYPE, bytes .cbor ratsd-claims, ], + text => cmw.cbor-record, } RATSD-CLAIMS-PROFILE = "tag:github.com,2026:veraison/ratsd/v2" ratsd-claims = #6.601({ &(eat_profile: 265) => RATSD-CLAIMS-PROFILE, &(eat_nonce: 10) => bytes .size (8 .. 64), &(oemid: 258) => eat.oemid-pen / eat.oemid-ieee / eat.oemid-\ random, &(sw-name: 270) => text, &(sw-version: 271) => eat.sw-version-type, ? ( &(nonce_adjust_function: -65537) => \ nonce_adjust_function_type, &(nonce_adjust_map: -65538) => {+ text => uint}, ), }) nonce_adjust_function_type /= "shake-128" / "shake-256" RATSD-CLAIMS-MEDIATYPE = ("application/eat-ucs+cbor; eat_profile=\"\ " .cat RATSD-CLAIMS-PROFILE) .cat "\"" RATSD-CMWCT = "tag:github.com,2025:veraison/ratsd/cmw/v2" cose.label = int / tstr Fossati, et al. Expires 4 January 2027 [Page 5] Internet-Draft RARE July 2026 cose.values = any cbor-record = cmw.cbor-record cmw.cbor-record = [ type: cmw.coap-content-format-type / cmw.media-type, value: bytes, ? ind: uint .bits cmw.cm-type, ] cmw.coap-content-format-type = uint .size 2 cmw.media-type = text .abnf ("Content-Type" .cat cmw.Content-Type-\ ABNF) cmw.cm-type = &( reference-values: 0, endorsements: 1, evidence: 2, attestation-results: 3, appraisal-policy: 4, ) cmw.Content-Type-ABNF = ' Content-Type = Media-Type-Name *( *SP ";" *SP parameter ) parameter = token "=" ( token / quoted-string ) token = 1*tchar tchar = "!" / "#" / "$" / "%" / "&" / "\'" / "*" / "+" / "-" / "." / "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA quoted-string = %x22 *( qdtext / quoted-pair ) %x22 qdtext = SP / %x21 / %x23-5B / %x5D-7E quoted-pair = "\\" ( SP / VCHAR ) Media-Type-Name = type-name "/" subtype-name type-name = restricted-name subtype-name = restricted-name restricted-name = restricted-name-first *126restricted-name-chars restricted-name-first = ALPHA / DIGIT restricted-name-chars = ALPHA / DIGIT / "!" / "#" / "$" / "&" / "-" / "^" / "_" restricted-name-chars =/ "." ; Characters before first dot always ; specify a facet name restricted-name-chars =/ "+" ; Characters after last plus always ; specify a structured syntax suffix DIGIT = %x30-39 ; 0 - 9 POS-DIGIT = %x31-39 ; 1 - 9 ALPHA = %x41-5A / %x61-7A ; A - Z / a - z SP = %x20 Fossati, et al. Expires 4 January 2027 [Page 6] Internet-Draft RARE July 2026 VCHAR = %x21-7E ; printable ASCII (no SP) ' sw-version-type = eat.sw-version-type eat.sw-version-type = [ version: tstr, ? scheme: $version-scheme, ] eat.oemid-pen = int eat.oemid-ieee = eat.JC eat.oemid-random = eat.JC eat.JC = eat.JSON-ONLY / eat.CBOR-ONLY eat.JSON-ONLY = J .feature "json" eat.CBOR-ONLY = C .feature "cbor" eat.oemid-ieee-json = tstr .b64u eat.oemid-ieee-cbor eat.oemid-ieee-cbor = bstr .size 3 eat.oemid-random-json = tstr .b64u eat.oemid-random-cbor eat.oemid-random-cbor = bstr .size 16 oemid-pen = eat.oemid-pen oemid-ieee = eat.oemid-ieee oemid-random = eat.oemid-random Appendix B. OpenAPI Schema TODO openapi Acknowledgments The APIs described in this document were designed and prototyped as part of the Veraison project over the past few years. The authors would like to thank the Veraison community, and in particular Dhanus M Lal, Ding Ma, Ian Chin Wang, Ian Oliver, Jag Raman, Sergei Trofimov, Shefali Kamal, Simon Frost and Yogesh Deshpande, for their invaluable contributions. Authors' Addresses Thomas Fossati Independent Email: tho.ietf@gmail.org Henk Birkholz Fraunhofer SIT Email: henk.birkholz@ietf.contact Fossati, et al. Expires 4 January 2027 [Page 7] Internet-Draft RARE July 2026 Nathanael Ritz Independent Email: ietf@nritz.com Paul Howard Arm Email: paul.howard@arm.com Fossati, et al. Expires 4 January 2027 [Page 8]