RATS L. Lundblade Internet-Draft Security Theory LLC Intended status: Standards Track H. Birkholz Expires: 7 March 2023 Fraunhofer SIT T. Fossati arm 3 September 2022 EAT Media Types draft-ietf-rats-eat-media-type-00 Abstract Payloads used in Remote Attestation Procedures may require an associated media type for their conveyance, for example when used in RESTful APIs. This memo defines media types to be used for Entity Attestation Tokens (EAT). Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the Remote ATtestation ProcedureS Working Group mailing list (rats@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/rats/. Source for this draft and an issue tracker can be found at https://github.com/thomas-fossati/draft-eat-mt. 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 March 2023. Lundblade, et al. Expires 7 March 2023 [Page 1] Internet-Draft EAT Media Types September 2022 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. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. EAT Types . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. A Media Type Parameter for EAT Profiles . . . . . . . . . . . 4 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6.1. Media Types . . . . . . . . . . . . . . . . . . . . . . . 6 6.2. application/eat-cwt Registration . . . . . . . . . . . . 6 6.3. application/eat-jwt Registration . . . . . . . . . . . . 7 6.4. application/eat-deb+cbor Registration . . . . . . . . . . 7 6.5. application/eat-deb+json Registration . . . . . . . . . . 8 6.6. application/eat-ucs+cbor Registration . . . . . . . . . . 8 6.7. application/eat-ucs+json Registration . . . . . . . . . . 9 6.8. Content-Format . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . 11 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction Payloads used in Remote Attestation Procedures [RATS-Arch] may require an associated media type for their conveyance, for example when used in RESTful APIs (Figure 1). Lundblade, et al. Expires 7 March 2023 [Page 2] Internet-Draft EAT Media Types September 2022 .----. .----------. .----------. | RP | | Attester | | Verifier | '-+--' '----+-----' '-----+----' | | POST /verify | | | EAT(Evidence) | | +--------------------------->| | | 200 OK | | | EAT(Attestation Results) | | |<---------------------------+ | POST /auth | | | EAT(Attestation Results) | | |<---------------------------+ | | 201 Created | | +--------------------------->| | | | | | | | Figure 1: Conveying RATS conceptual messages in REST APIs using EAT This memo defines media types to be used for Entity Attestation Token (EAT) [EAT] payloads independently of the RATS Conceptual Message in which they manifest themselves. 1.1. Requirements Language This document uses the terms and concepts defined in [RATS-Arch]. 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. EAT Types Figure 2 illustrates the six EAT wire formats and how they relate to each other. [EAT] defines four of them (CWT, JWT and DEB in its JSON and CBOR flavours), whilst [UCCS] defines the remaining two: UCCS and UJCS. Lundblade, et al. Expires 7 March 2023 [Page 3] Internet-Draft EAT Media Types September 2022 .-----. .----+ UJCS |<-------------------------. | '-----' | | | | .-----. | +-----+ UCCS |<-----------------------. | | '-----' | | | | | | .------. | | +-----+ JWT |<------. | | | '------' .--+---. | | | | Crypto |<------. | | | .------. '--+---' | | | +-----+ CWT |<------' | | | | '------' .---+-+-+----. | | Claims-Set +--. | .------. '---+---+----' | +-----+ DEB-J |<------. | ^ | v | '------' .--+---. | | | .------. | | Bundle |<------' | | | Digest | | .------. '--+---' | v '--+---' +-----+ DEB-C |<------' ^ .---+----. | | '------' | | submod |<---' | | '--------' v | ^ .--------------. | | | Nested-Token +-----------------+------------' '--------------' .-------. .---------. .------. Legenda: | Process | | Wire Fmt | | CDDL | '-------' '---------' '------' Figure 2: EAT Types 3. A Media Type Parameter for EAT Profiles EAT is an open and flexible format. To improve interoperability, Section 7 of [EAT] defines the concept of EAT profiles. Profiles are used to constrain the parameters that producers and consumers of a specific EAT profile need to understand in order to interoperate. For example: the number and type of claims, which serialisation format, the supported signature schemes, etc. EATs carry an in-band profile identifier using the eat_profile claim (see Section 4.3.3 of [EAT]). The value of the eat_profile claim is either an OID or a URI. Lundblade, et al. Expires 7 March 2023 [Page 4] Internet-Draft EAT Media Types September 2022 The media types defined in this document include an optional profile parameter that can be used to mirror the eat_profile claim of the transported EAT. Exposing the EAT profile at the API layer allows API routers to dispatch payloads directly to the profile-specific processor without having to snoop into the request bodies. This design also provides a finer-grained and scalable type system that matches the inherent extensibility of EAT. The expectation being that a certain EAT profile automatically obtains a media type derived from the base (e.g., application/eat-cwt) by populating the profile parameter with the corresponding OID or URL. 4. Examples The example in Figure 3 illustrates the usage of EAT media types for transporting attestation evidence. POST /challenge-response/v1/session/1234567890 HTTP/1.1 Host: verifier.example Accept: application/eat-cwt; profile="tag:ar4si.example,2021" Content-Type: application/eat-cwt; profile="tag:evidence.example,2022" [ CBOR-encoded EAT w/ profile="tag:evidence.example,2022" ] Figure 3: Example REST Verification API (request) The example in Figure 4 illustrates the usage of EAT media types for transporting attestation results. HTTP/1.1 200 OK Content-Type: application/eat-cwt; profile="tag:ar4si.example,2021" [ CBOR-encoded EAT w/ profile="tag:ar4si.example,2021" ] Figure 4: Example REST Verification API (response) In both cases the profile is carried as an explicit parameter. 5. Security Considerations The security consideration of [EAT] and [UCCS] apply in full. 6. IANA Considerations // RFC Editor: please replace RFCthis with this RFC number and remove // this note. Lundblade, et al. Expires 7 March 2023 [Page 5] Internet-Draft EAT Media Types September 2022 6.1. Media Types IANA is requested to add the following media types to the "Media Types" registry [IANA.media-types]. +==============+==========================+======================+ | Name | Template | Reference | +==============+==========================+======================+ | EAT CWT | application/eat-cwt | RFCthis, Section 6.2 | +--------------+--------------------------+----------------------+ | EAT JWT | application/eat-jwt | RFCthis, Section 6.3 | +--------------+--------------------------+----------------------+ | EAT CBOR DEB | application/eat-deb+cbor | RFCthis, Section 6.4 | +--------------+--------------------------+----------------------+ | EAT JSON DEB | application/eat-deb+json | RFCthis, Section 6.5 | +--------------+--------------------------+----------------------+ | EAT UCCS | application/eat-ucs+cbor | RFCthis, Section 6.6 | +--------------+--------------------------+----------------------+ | EAT UJCS | application/eat-ucs+json | RFCthis, Section 6.7 | +--------------+--------------------------+----------------------+ Table 1: New Media Types 6.2. application/eat-cwt Registration Type name: application Subtype name: eat-cwt Required parameters: n/a Optional parameters: "profile" (EAT profile in string format. OIDs MUST use the dotted-decimal notation. The parameter value is case-insensitive.) Encoding considerations: binary Security considerations: Section 5 of RFCthis Interoperability considerations: n/a Published specification: Section 6.1 of RFCthis Applications that use this media type: Attesters, Verifiers, Endorsers and Reference-Value providers, Relying Parties that need to transfer EAT payloads over HTTP(S), CoAP(S), and other transports. Fragment identifier considerations: n/a Person & email address to contact for further information: RATS WG mailing list (rats@ietf.org) Intended usage: COMMON Restrictions on usage: none Author/Change controller: IETF Provisional registration: // maybe Lundblade, et al. Expires 7 March 2023 [Page 6] Internet-Draft EAT Media Types September 2022 6.3. application/eat-jwt Registration Type name: application Subtype name: eat-jwt Required parameters: n/a Optional parameters: "profile" (EAT profile in string format. OIDs MUST use the dotted-decimal notation. The parameter value is case-insensitive.) Encoding considerations: 8bit Security considerations: Section 5 of RFCthis Interoperability considerations: n/a Published specification: Section 6.1 of RFCthis Applications that use this media type Attesters, Verifiers, Endorsers and Reference-Value providers, Relying Parties that need to transfer EAT payloads over HTTP(S), CoAP(S), and other transports. Fragment identifier considerations: n/a Person & email address to contact for further information: RATS WG mailing list (rats@ietf.org) Intended usage: COMMON Restrictions on usage: none Author/Change controller: IETF Provisional registration: // maybe 6.4. application/eat-deb+cbor Registration Type name: application Subtype name: eat-deb+cbor Required parameters: n/a Optional parameters: "profile" (EAT profile in string format. OIDs MUST use the dotted-decimal notation. The parameter value is case-insensitive.) Encoding considerations: binary Security considerations: Section 5 of RFCthis Interoperability considerations: n/a Published specification: Section 6.1 of RFCthis Applications that use this media type: Attesters, Verifiers, Endorsers and Reference-Value providers, Relying Parties that need to transfer EAT payloads over HTTP(S), CoAP(S), and other transports. Fragment identifier considerations: n/a Person & email address to contact for further information: RATS WG mailing list (rats@ietf.org) Intended usage: COMMON Restrictions on usage: none Author/Change controller: IETF Provisional registration: Lundblade, et al. Expires 7 March 2023 [Page 7] Internet-Draft EAT Media Types September 2022 // maybe 6.5. application/eat-deb+json Registration Type name: application Subtype name: eat-deb+json Required parameters: n/a Optional parameters: "profile" (EAT profile in string format. OIDs MUST use the dotted-decimal notation. The parameter value is case-insensitive.) Encoding considerations: Same as [RFC7159] Security considerations: Section 5 of RFCthis Interoperability considerations: n/a Published specification: Section 6.1 of RFCthis Applications that use this media type Attesters, Verifiers, Endorsers and Reference-Value providers, Relying Parties that need to transfer EAT payloads over HTTP(S), CoAP(S), and other transports. Fragment identifier considerations: n/a Person & email address to contact for further information: RATS WG mailing list (rats@ietf.org) Intended usage: COMMON Restrictions on usage: none Author/Change controller: IETF Provisional registration: // maybe 6.6. application/eat-ucs+cbor Registration Type name: application Subtype name: eat-ucs+cbor Required parameters: n/a Optional parameters: "profile" (EAT profile in string format. OIDs MUST use the dotted-decimal notation. The parameter value is case-insensitive.) Encoding considerations: binary Security considerations: Section 5 of RFCthis Interoperability considerations: n/a Published specification: Section 6.1 of RFCthis Applications that use this media type: Attesters, Verifiers, Endorsers and Reference-Value providers, Relying Parties that need to transfer EAT payloads over HTTP(S), CoAP(S), and other transports. Fragment identifier considerations: n/a Person & email address to contact for further information: RATS WG mailing list (rats@ietf.org) Intended usage: COMMON Restrictions on usage: none Lundblade, et al. Expires 7 March 2023 [Page 8] Internet-Draft EAT Media Types September 2022 Author/Change controller: IETF Provisional registration: // maybe 6.7. application/eat-ucs+json Registration Type name: application Subtype name: eat-ucs+json Required parameters: n/a Optional parameters: "profile" (EAT profile in string format. OIDs MUST use the dotted-decimal notation. The parameter value is case-insensitive.) Encoding considerations: Same as [RFC7159] Security considerations: Section 5 of RFCthis Interoperability considerations: n/a Published specification: Section 6.1 of RFCthis Applications that use this media type Attesters, Verifiers, Endorsers and Reference-Value providers, Relying Parties that need to transfer EAT payloads over HTTP(S), CoAP(S), and other transports. Fragment identifier considerations: n/a Person & email address to contact for further information: RATS WG mailing list (rats@ietf.org) Intended usage: COMMON Restrictions on usage: none Author/Change controller: IETF Provisional registration: // maybe 6.8. Content-Format | (*Issue*: need a way to pass the profile information when using | content formats. A new CoAP option?) IANA is requested to register a Content-Format number in the "CoAP Content-Formats" sub-registry, within the "Constrained RESTful Environments (CoRE) Parameters" Registry [IANA.core-parameters], as follows: Lundblade, et al. Expires 7 March 2023 [Page 9] Internet-Draft EAT Media Types September 2022 +==========================+================+======+===========+ | Content-Type | Content Coding | ID | Reference | +==========================+================+======+===========+ | application/eat-cwt | - | TBD1 | RFCthis | +--------------------------+----------------+------+-----------+ | application/eat-jwt | - | TBD2 | RFCthis | +--------------------------+----------------+------+-----------+ | application/eat-deb+cbor | - | TBD3 | RFCthis | +--------------------------+----------------+------+-----------+ | application/eat-deb+json | - | TBD4 | RFCthis | +--------------------------+----------------+------+-----------+ | application/eat-ucs+cbor | - | TBD5 | RFCthis | +--------------------------+----------------+------+-----------+ | application/eat-ucs+json | - | TBD6 | RFCthis | +--------------------------+----------------+------+-----------+ Table 2: New Content-Formats TBD1..6 are to be assigned from the space 256..999. In the registry as defined by Section 12.3 of [CoAP] at the time of writing, the column "Content-Type" is called "Media type" and the column "Content Coding" is called "Encoding". // RFC editor: please remove this paragraph. 7. References 7.1. Normative References [CoAP] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, June 2014, . [EAT] Lundblade, L., Mandyam, G., and J. O'Donoghue, "The Entity Attestation Token (EAT)", Work in Progress, Internet- Draft, draft-ietf-rats-eat-14, 10 July 2022, . [IANA.core-parameters] IANA, "Constrained RESTful Environments (CoRE) Parameters", 8 June 2012, . [IANA.media-types] IANA, "Media Types", 1 September 2022, . Lundblade, et al. Expires 7 March 2023 [Page 10] Internet-Draft EAT Media Types September 2022 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [UCCS] Birkholz, H., O'Donoghue, J., Cam-Winget, N., and C. Bormann, "A CBOR Tag for Unprotected CWT Claims Sets", Work in Progress, Internet-Draft, draft-ietf-rats-uccs-03, 11 July 2022, . 7.2. Informative References [RATS-Arch] Birkholz, H., Thaler, D., Richardson, M., Smith, N., and W. Pan, "Remote Attestation Procedures Architecture", Work in Progress, Internet-Draft, draft-ietf-rats-architecture- 21, 16 August 2022, . Acknowledgments TODO Authors' Addresses Laurence Lundblade Security Theory LLC Email: lgl@securitytheory.com Henk Birkholz Fraunhofer Institute for Secure Information Technology Rheinstrasse 75 64295 Darmstadt Germany Email: henk.birkholz@sit.fraunhofer.de Lundblade, et al. Expires 7 March 2023 [Page 11] Internet-Draft EAT Media Types September 2022 Thomas Fossati arm Email: thomas.fossati@arm.com Lundblade, et al. Expires 7 March 2023 [Page 12]