Remote ATtestation ProcedureS

Internet Engineering Task Force (IETF)                      L. Lundblade
Internet-Draft
Request for Comments: 9782                           Security Theory LLC
Intended status:
Category: Standards Track                                    H. Birkholz
Expires: 7 May 2025
ISSN: 2070-1721                                           Fraunhofer SIT
                                                              T. Fossati
                                                                  Linaro
                                                         3 November 2024

                            EAT
                                                              April 2025

               Entity Attestation Token (EAT) Media Types
                   draft-ietf-rats-eat-media-type-12

Abstract

   Payloads used in Remote Attestation Procedures ATtestation procedureS (RATS) may require an
   associated media type for their conveyance, for example 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. (EATs).

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 an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list  It represents the consensus of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid the IETF community.  It has
   received public review and has been approved for a maximum publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of six months RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be updated, replaced, or obsoleted by other documents obtained at any
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 7 May 2025.
   https://www.rfc-editor.org/info/rfc9782.

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   Copyright (c) 2024 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3  Terminology
   2.  EAT Types . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  A Media Type Parameter for EAT Profiles . . . . . . . . . . .   4
   4.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  +cwt Structured Syntax Suffix . . . . . . . . . . . . . .   6
       6.1.1.  Registry Contents . . . . . . . . . . . . . . . . . .   6
     6.2.  Media Types . . . . . . . . . . . . . . . . . . . . . . .   7
     6.3.  application/eat+cwt Registration  . . . . . . . . . . . .   7
     6.4.  application/eat+jwt Registration  . . . . . . . . . . . .   8
     6.5.  application/eat-bun+cbor Registration . . . . . . . . . .   8
     6.6.  application/eat-bun+json Registration . . . . . . . . . .   9
     6.7.  application/eat-ucs+cbor Registration . . . . . . . . . .   9
     6.8.  application/eat-ucs+json Registration . . . . . . . . . .  10
     6.9.  CoAP Content-Format Registrations . . . . . . . . . . . .  10
   7.  Changelog . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.1.   -04  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.2.   -03  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.3.   -02  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     7.4.   -01  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     8.1.
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     8.2.
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   Payloads used in Remote Attestation Procedures [RATS-Arch] ATtestation procedureS (RATS) [RATS-ARCH] may
   require an associated media type for their conveyance, for example example,
   when used in RESTful APIs (Figure 1).

      .---------------.         .----------.             .----------.
      | Relying Party |         | Attester |             | Verifier |
      '-+-------------'         '----+-----'             '--------+-'
        |                            | POST /verify               |
        |                            | EAT(Evidence)              |
        |                            +--------------------------->|
        |                            |                     200 OK |
        |                            |   EAT(Attestation Results) |
        |                            |<---------------------------+
        |                 POST /auth |                            |
        |   EAT(Attestation Results) |                            |
        |<---------------------------+                            |
        | 201 Created                |                            |
        +--------------------------->|                            |
        |                            |                            |
        |                            |                            |

    Figure 1: Conveying RATS conceptual messages Conceptual Messages in REST APIs using EAT Using EATs

   This memo defines media types to be used for Entity Attestation Token
   (EAT) [EAT] EAT payloads [EAT]
   independently of the RATS Conceptual Message in which they manifest
   themselves.  The objective is to give protocol,
   API API, and application
   designers a number of readily available and reusable media types for
   integrating EAT-based messages in their flows, for example e.g., when using HTTP
   [BUILD-W-HTTP] or CoAP the Constrained Application Protocol (CoAP)
   [REST-IoT].

1.1.  Requirements Language  Terminology

   This document uses the terms and concepts defined in [RATS-Arch]. [RATS-ARCH].

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 (CBOR Web Token (CWT), JSON
   Web Token (JWT), and Detached the detached EAT
   Bundle bundle in its JSON and CBOR
   flavours), whilst while [UCCS] defines UCCS the Unprotected CWT Claims Set (UCCS)
   and
   UJCS. Unprotected JWT Claims Sets (UJCS).

                    .-----.
              .----+ UJCS |<-------------------------.
             |     '-----'                            |
             |                                        |
             |      .-----.                           |
             +-----+ UCCS |<-----------------------.  |
             |     '-----'                          | |
             |                                      | |
             |      .------.                        | |
             +-----+  JWT  |<------.                | |
             |     '------'      .--+---.           | |
             |                  | Crypto |<------.  | |
             |      .------.     '--+---'         | | |
             +-----+  CWT  |<------'              | | |
             |     '------'                   .---+-+-+----.
             |                                | Claims-Set +--.
             |      .------.                  '---+---+----'   |
             +-----+ BUN-J |<------.              | ^ |        v
             |     '------'      .--+---.         | | |     .------.
             |                  | Bundle |<------'  | |    | Digest |
             |      .------.     '--+---'           | v     '--+---'
             +-----+ BUN-C |<------'  ^         .---+----.     |
             |     '------'           |         | submod |<---'
             |                        |         '--------'
             v                        |             ^
     .--------------.                 |             |
     | Nested-Token +-----------------+------------'
     '--------------'

                     .-------.     .---------.   .------.
          Legenda:
          Legend:   | 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 6 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: interoperate,
   e.g., 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 4.3.2 of [EAT]).
   The value of the eat_profile claim is either an OID or a URI.

   The media types defined in this document include an optional
   eat_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 eat_profile parameter with the corresponding OID or
   URL.

   When the parameterised version of the EAT media type is used in HTTP
   (for example, with the "Content-Type" and "Accept" headers), headers) and the
   value is an absolute URI (Section 4.3 of [URI]), the parameter-value
   (Appendix A of [HTTP]) uses the quoted-string encoding, e.g.: for example:

        application/eat+jwt; eat_profile="tag:evidence.example,2022"

   Instead, when the EAT profile is an OID, the token encoding (i.e.,
   without quotes) can be used, e.g.: used.  For example:

        application/eat+cwt; eat_profile=2.999.1.

4.  Examples

   The example in Figure 3 illustrates the usage of EAT media types for
   transporting attestation evidence as well as negotiating the
   acceptable format of the attestation result.

   #

   NOTE: '\' line wrapping per RFC 8792

   POST /challenge-response/v1/session/1234567890 HTTP/1.1
   Host: verifier.example
   Accept: application/eat+cwt; eat_profile="tag:ar4si.example,2021"
   Content-Type: application/eat+cwt; \
                 eat_profile="tag:evidence.example,2022"

   [ CBOR-encoded EAT w/ eat_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.

   #

   NOTE: '\' line wrapping per RFC 8792

   HTTP/1.1 200 OK
   Content-Type: application/eat+cwt; \
                 eat_profile="tag:ar4si.example,2021"

   [ CBOR-encoded EAT w/ eat_profile="tag:ar4si.example,2021" ]

             Figure 4: Example REST Verification API (response)

   In both cases, a tag URI [TAG] identifying the profile is carried as
   an explicit parameter.

5.  Security Considerations

   Media types only provide clues to the processing application.  The
   application must verify that the received data matches the expected
   format, regardless of the advertised media type, and stop further
   processing on failure.  Failing to do so could expose the user to
   security risks, such as privilege escalation and cross-protocol
   attacks.

   The security consideration considerations of [EAT] and [UCCS] apply in full.

   In particular, when

   When using application/eat-ucs+json and application/
   eat-ucs+cbor application/eat-ucs+cbor in
   particular, the reader should review Section 3 of [UCCS], which
   contains a detailed discussion about the characteristics of a "Secure
   Channel" for conveyance of such messages.

6.  IANA Considerations

   // RFC Editor: please replace RFCthis with this RFC number and remove
   // this note.

6.1.  +cwt Structured Syntax Suffix

   IANA is requested to register the has registered +cwt structured syntax suffix in the "Structured Syntax Suffixes" registry
   [IANA.media-type-structured-suffix]
   [STRUCT-SYNTAX] in the manner described in
   [MediaTypes], which [MEDIATYPES].  +cwt can be
   used to indicate that the media type is encoded as a CWT.

6.1.1.  Registry Contents

   Name:  CBOR Web Token (CWT)

   +suffix:  +cwt

   References:  [CWT]

   Encoding Considerations:  binary

   Interoperability Considerations:  N/A

   Fragment Identifier Considerations:  The syntax and semantics of
      fragment identifiers specified for +cwt SHOULD be as specified for
      application/cwt.  (At publication the time of this document, publication, there is no
      fragment identification syntax defined for application/cwt.)

   Security Considerations:  See Section 8 of [CWT]

   Contact:  RATS WG mailing list (rats@ietf.org), or IETF Security Area
      (saag@ietf.org)

   Author/Change Controller:  Remote ATtestation ProcedureS (RATS)
      Working Group.  The IETF has change control over this
      registration.

6.2.  Media Types

   IANA is requested to add has registered the following media types to in the "Media Types"
   registry [IANA.media-types].

   +==============+=====================+======================+ [MEDIA-TYPES].

      +==============+=====================+=======================+
      | Name         | Template            | Reference             |
   +==============+=====================+======================+
      +==============+=====================+=======================+
      | EAT CWT      | application/eat+cwt | RFCthis, RFC 9782, Section 6.3 |
   +--------------+---------------------+----------------------+
      +--------------+---------------------+-----------------------+
      | EAT JWT      | application/eat+jwt | RFCthis, RFC 9782, Section 6.4 |
   +--------------+---------------------+----------------------+
      +--------------+---------------------+-----------------------+
      | Detached EAT | application/eat-    | RFCthis, RFC 9782, Section 6.5 |
      | Bundle CBOR  | bun+cbor            |                       |
   +--------------+---------------------+----------------------+
      +--------------+---------------------+-----------------------+
      | Detached EAT | application/eat-    | RFCthis, RFC 9782, Section 6.6 |
      | Bundle JSON  | bun+json            |                       |
   +--------------+---------------------+----------------------+
      +--------------+---------------------+-----------------------+
      | EAT UCCS     | application/eat-    | RFCthis, RFC 9782, Section 6.7 |
      |              | ucs+cbor            |                       |
   +--------------+---------------------+----------------------+
      +--------------+---------------------+-----------------------+
      | EAT UJCS     | application/eat-    | RFCthis, RFC 9782, Section 6.8 |
      |              | ucs+json            |                       |
   +--------------+---------------------+----------------------+
      +--------------+---------------------+-----------------------+

                         Table 1: New Media Types

6.3.  application/eat+cwt Registration

   Type name:  application

   Subtype name:  eat+cwt

   Required parameters:  n/a

   Optional parameters:  "eat_profile" (EAT profile in string format.
      OIDs must use the dotted-decimal notation.  The parameter value is
      case-insensitive.)
      case insensitive.)

   Encoding considerations:  binary

   Security considerations:  Section 9 of [EAT]

   Interoperability considerations:  n/a

   Published specification:  RFCthis  RFC 9782

   Applications that use this media type:  Attesters, Verifiers,
      Endorsers and Reference-Value providers, and 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:  no

6.4.  application/eat+jwt Registration

   Type name:  application

   Subtype name:  eat+jwt

   Required parameters:  n/a

   Optional parameters:  "eat_profile" (EAT profile in string format.
      OIDs must use the dotted-decimal notation.  The parameter value is
      case-insensitive.)
      case insensitive.)

   Encoding considerations:  8bit

   Security considerations:  Section 9 of [EAT] and [BCP225]

   Interoperability considerations:  n/a

   Published specification:  RFCthis  RFC 9782

   Applications that use this media type type:  Attesters, Verifiers,
      Endorsers and Reference-Value providers, and 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:  no

6.5.  application/eat-bun+cbor Registration

   Type name:  application

   Subtype name:  eat-bun+cbor

   Required parameters:  n/a

   Optional parameters:  "eat_profile" (EAT profile in string format.
      OIDs must use the dotted-decimal notation.  The parameter value is
      case-insensitive.)
      case insensitive.)

   Encoding considerations:  binary

   Security considerations:  Section 9 of [EAT]

   Interoperability considerations:  n/a

   Published specification:  RFCthis  RFC 9782

   Applications that use this media type:  Attesters, Verifiers,
      Endorsers and Reference-Value providers, and 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:  no

6.6.  application/eat-bun+json Registration

   Type name:  application

   Subtype name:  eat-bun+json

   Required parameters:  n/a

   Optional parameters:  "eat_profile" (EAT profile in string format.
      OIDs must use the dotted-decimal notation.  The parameter value is
      case-insensitive.)
      case insensitive.)

   Encoding considerations:  Same as [JSON]

   Security considerations:  Section 9 of [EAT]

   Interoperability considerations:  n/a

   Published specification:  RFCthis  RFC 9782

   Applications that use this media type type:  Attesters, Verifiers,
      Endorsers and Reference-Value providers, and 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:  no

6.7.  application/eat-ucs+cbor Registration

   Type name:  application

   Subtype name:  eat-ucs+cbor

   Required parameters:  n/a

   Optional parameters:  "eat_profile" (EAT profile in string format.
      OIDs must use the dotted-decimal notation.  The parameter value is
      case-insensitive.)
      case insensitive.)

   Encoding considerations:  binary

   Security considerations:  Sections 3 and 7 of [UCCS]

   Interoperability considerations:  n/a

   Published specification:  RFCthis  RFC 9782

   Applications that use this media type:  Attesters, Verifiers,
      Endorsers and Reference-Value providers, and 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:  no

6.8.  application/eat-ucs+json Registration

   Type name:  application

   Subtype name:  eat-ucs+json

   Required parameters:  n/a

   Optional parameters:  "eat_profile" (EAT profile in string format.
      OIDs must use the dotted-decimal notation.  The parameter value is
      case-insensitive.)
      case insensitive.)

   Encoding considerations:  Same as [JSON]

   Security considerations:  Sections 3 and 7 of [UCCS]

   Interoperability considerations:  n/a

   Published specification:  RFCthis  RFC 9782

   Applications that use this media type type:  Attesters, Verifiers,
      Endorsers and Reference-Value providers, and 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:  no

6.9.  CoAP Content-Format Registrations

   IANA is requested to register has registered the following Content-Format numbers in the "CoAP
   Content-Formats" sub-registry, registry, within the "Constrained RESTful
   Environments (CoRE) Parameters" Registry
   [IANA.core-parameters]:

   +==========================+================+======+===========+ registry group [CORE-PARAMS]:

      +==========================+================+=====+===========+
      | Content-Type Content Type             | Content Coding | ID  | Reference |
   +==========================+================+======+===========+
      +==========================+================+=====+===========+
      | application/eat+cwt      | -              | TBD1 263 | RFCthis RFC 9782  |
   +--------------------------+----------------+------+-----------+
      +--------------------------+----------------+-----+-----------+
      | application/eat+jwt      | -              | TBD2 264 | RFCthis RFC 9782  |
   +--------------------------+----------------+------+-----------+
      +--------------------------+----------------+-----+-----------+
      | application/eat-bun+cbor | -              | TBD3 265 | RFCthis RFC 9782  |
   +--------------------------+----------------+------+-----------+
      +--------------------------+----------------+-----+-----------+
      | application/eat-bun+json | -              | TBD4 266 | RFCthis RFC 9782  |
   +--------------------------+----------------+------+-----------+
      +--------------------------+----------------+-----+-----------+
      | application/eat-ucs+cbor | -              | TBD5 267 | RFCthis RFC 9781  |
   +--------------------------+----------------+------+-----------+
      +--------------------------+----------------+-----+-----------+
      | application/eat-ucs+json | -              | TBD6 268 | RFCthis RFC 9782  |
   +--------------------------+----------------+------+-----------+
      +--------------------------+----------------+-----+-----------+

                        Table 2: New Content-Formats

   TBD1..6 are to be assigned from the space 256..9999.

7.  Changelog

   // RFC editor: please remove this section

7.1.   -04

   *  Early IANA review

7.2.   -03

   *  Update references

7.3.   -02

   *  Update references

   *  Register +cwt SSS (Issue#14 (https://github.com/ietf-rats-wg/
      draft-eat-mt/issues/14))

   *  Move from eat-jwt to eat+jwt (Issue#14 (https://github.com/ietf-
      rats-wg/draft-eat-mt/issues/14))

   *  Move from eat-cwt to eat+cwt (Issue#14 (https://github.com/ietf-
      rats-wg/draft-eat-mt/issues/14))

7.4.   -01

   *  Rename profile to eat_profile for consistency with EAT (Issue#4
      (https://github.com/ietf-rats-wg/draft-eat-mt/issues/4))

   *  The DEB acronym is gone: shorthand is now "bun" from bundle
      (Issue#8 (https://github.com/ietf-rats-wg/draft-eat-mt/issues/8))

   *  Incorporate editorial suggestions from Carl and Dave (Issue#7
      (https://github.com/ietf-rats-wg/draft-eat-mt/issues/7), Issue#9
      (https://github.com/ietf-rats-wg/draft-eat-mt/issues/9))

8.  References

8.1.

7.1.  Normative References

   [BCP225]   Best Current Practice 225,
              <https://www.rfc-editor.org/info/bcp225>.
              At the time of writing, this BCP comprises the following:

              Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
              Current Practices", BCP 225, RFC 8725,
              DOI 10.17487/RFC8725, February 2020,
              <https://www.rfc-editor.org/info/rfc8725>.

   [CORE-PARAMS]
              IANA, "CoAP Content-Formats",
              <https://www.iana.org/assignments/core-parameters>.

   [CWT]      Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
              "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
              May 2018, <https://www.rfc-editor.org/rfc/rfc8392>. <https://www.rfc-editor.org/info/rfc8392>.

   [EAT]      Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
              Wallace, "The Entity Attestation Token (EAT)", Work in
              Progress, Internet-Draft, draft-ietf-rats-eat-31, 6
              September 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-rats-eat-31>. RFC 9711,
              DOI 10.17487/RFC9711, April 2025,
              <https://www.rfc-editor.org/info/rfc9711>.

   [HTTP]     Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/rfc/rfc9110>.

   [IANA.core-parameters]
              IANA, "Constrained RESTful Environments (CoRE)
              Parameters",
              <https://www.iana.org/assignments/core-parameters>.

   [IANA.media-type-structured-suffix]
              IANA, "Structured Syntax Suffixes",
              <https://www.iana.org/assignments/media-type-structured-
              suffix>.

   [IANA.media-types]
              IANA, "Media Types",
              <https://www.iana.org/assignments/media-types>.
              <https://www.rfc-editor.org/info/rfc9110>.

   [JSON]     Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/rfc/rfc8259>.
              <https://www.rfc-editor.org/info/rfc8259>.

   [JWT]      Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/rfc/rfc7519>.

   [MediaTypes]
              <https://www.rfc-editor.org/info/rfc7519>.

   [MEDIA-TYPES]
              IANA, "Media Types",
              <https://www.iana.org/assignments/media-types>.

   [MEDIATYPES]
              Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/rfc/rfc6838>.
              <https://www.rfc-editor.org/info/rfc6838>.

   [STRUCT-SYNTAX]
              IANA, "Structured Syntax Suffixes",
              <https://www.iana.org/assignments/media-type-structured-
              suffix>.

   [UCCS]     Birkholz, H., O'Donoghue, J., Cam-Winget, N., and C.
              Bormann, "A CBOR Concise Binary Object Representation (CBOR)
              Tag for Unprotected CWT CBOR Web Token Claims Sets",
              Work in Progress, Internet-Draft, draft-ietf-rats-uccs-12,
              3 November 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-rats-uccs-12>. Sets (UCCS)",
              RFC 9781, DOI 10.17487/RFC9781, April 2025,
              <https://www.rfc-editor.org/info/rfc9781>.

   [URI]      Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/rfc/rfc3986>.

8.2.
              <https://www.rfc-editor.org/info/rfc3986>.

7.2.  Informative References

   [BUILD-W-HTTP]
              Best Current Practice 56,
              <https://www.rfc-editor.org/info/bcp56>.
              At the time of writing, this BCP comprises the following:

              Nottingham, M., "Building Protocols with HTTP", BCP 56,
              RFC 9205, DOI 10.17487/RFC9205, June 2022,
              <https://www.rfc-editor.org/info/rfc9205>.

   [RATS-Arch]

   [RATS-ARCH]
              Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote ATtestation procedureS (RATS)
              Architecture", RFC 9334, DOI 10.17487/RFC9334, January
              2023, <https://www.rfc-editor.org/rfc/rfc9334>. <https://www.rfc-editor.org/info/rfc9334>.

   [REST-IoT] Keränen, A., Kovatsch, M., and K. Hartke, "Guidance on
              RESTful Design for Internet of Things Systems", Work in
              Progress, Internet-Draft, draft-irtf-t2trg-rest-iot-15, 21
              October 2024, <https://datatracker.ietf.org/doc/html/
              draft-irtf-t2trg-rest-iot-15>.

   [TAG]      Kindberg, T. and S. Hawke, "The 'tag' URI Scheme",
              RFC 4151, DOI 10.17487/RFC4151, October 2005,
              <https://www.rfc-editor.org/rfc/rfc4151>.
              <https://www.rfc-editor.org/info/rfc4151>.

Acknowledgments

   Thank you Carl Wallace, Carsten Bormann, Dave Thaler, Deb Cooley,
   Éric Vyncke, Francesca Palombini, Jouni Korhonen, Kathleen Moriarty,
   Michael Richardson, Murray Kucherawy, Orie Steele, Paul Howard, Roman
   Danyliw
   Danyliw, and Tim Hollebeek for your comments and suggestions.

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@ietf.contact

   Thomas Fossati
   Linaro
   Email: thomas.fossati@linaro.org