RATS Working Group                                          L. Lundblade
Internet-Draft                                       Security Theory LLC
Intended status: Standards Track                              G. Mandyam
Expires: April 26, August 27, 2022                                   J. O'Donoghue
                                              Qualcomm Technologies Inc.
                                                        October
                                                       February 23, 2021 2022

                   The Entity Attestation Token (EAT)
                         draft-ietf-rats-eat-11
                         draft-ietf-rats-eat-12

Abstract

   An Entity Attestation Token (EAT) provides a signed (attested) set of an attested claims set
   that describe describes state and characteristics of an entity,
   typically a device like
   a phone or an phone, IoT device.  These device, network equipment or such.  This claims are set is
   used by a Relying Party relying party, server or service to determine how much it
   wishes to trust the entity.

   An EAT is either a CWT CBOR Web Token (CWT) or JWT JSON Web Token (JWT) with some
   attestation-oriented claims.  To a large degree, all this document
   does is extend CWT and JWT.

Status of This Memo

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   This Internet-Draft will expire on April 26, August 27, 2022.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   5
     1.1.  CWT, JWT, UCCS, UJCS and DEB  . .  Entity Overview . . . . . . . . . . . .   5
     1.2.  CDDL, CBOR and JSON . . . . . . . . .   6
     1.2.  CWT, JWT, UCCS, UJCS and DEB  . . . . . . . . . .   6
     1.3.  Operating Model and RATS Architecture . . . .   7
     1.3.  CDDL, CBOR and JSON . . . . . .   7
       1.3.1.  Use as Attestation Evidence . . . . . . . . . . . . .   8
       1.3.2.  Use as Attestation Results  . . .
     1.4.  Operating Model and RATS Architecture . . . . . . . . . .   8
     1.4.  Entity Overview . . . .
       1.4.1.  Relationship between Attestation Evidence and
               Attestation Results . . . . . . . . . . . . . . . . .   9
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   9  10
   3.  The Claims  . . . . . . . . . . . . . . . . . . . . . . . . .  10  11
     3.1.  Token ID Claim (cti and jti)  . . . . . . . . . . . . . .  11
     3.2.  Timestamp claim (iat) . . . . . . . . . . . . . . . . . .  11
     3.3.  Nonce Claim (nonce) . . . . . . . . . . . . . . . . . . .  11  12
     3.4.  Universal Entity ID Claim (ueid)  . . . . . . . . . . . .  12
     3.5.  Semi-permanent UEIDs (SUEIDs) . . . . . . . . . . . . . .  14  15
     3.6.  Hardware OEM Identification (oemid) . . . . . . . . . . .  15  16
       3.6.1.  Random Number Based OEMID . . . . . . . . . . . . . . . . .  15  16
       3.6.2.  IEEE Based OEMID  . . . . . . . . . . . . . . . . . . . . .  15  16
       3.6.3.  IANA Private Enterprise Number Based OEMID  . . . . .  17
     3.7.  Hardware Model Claim (hardware-model) . . . . . . . . .  16
     3.7. .  17
     3.8.  Hardware Version Claims (hardware-version-claims) . . . .  16
     3.8.  18
     3.9.  Software Name Claim . . . . . . . . . . . . . . . . . . .  17
     3.9.  19
     3.10. Software Version Claim  . . . . . . . . . . . . . . . . .  17
     3.10.  19
     3.11. The Security Level Claim (security-level) . . . . . . . .  17
     3.11.  19
     3.12. Secure Boot Claim (secure-boot) . . . . . . . . . . . . .  19
     3.12.  21
     3.13. Debug Status Claim (debug-status) . . . . . . . . . . . .  19
       3.12.1.  21
       3.13.1.  Enabled  . . . . . . . . . . . . . . . . . . . . . .  20
       3.12.2.  22
       3.13.2.  Disabled . . . . . . . . . . . . . . . . . . . . . .  20
       3.12.3.  22
       3.13.3.  Disabled Since Boot  . . . . . . . . . . . . . . . .  21
       3.12.4.  22
       3.13.4.  Disabled Permanently . . . . . . . . . . . . . . . .  21
       3.12.5.  22
       3.13.5.  Disabled Fully and Permanently . . . . . . . . . . .  21
     3.13.  22
     3.14. Including Keys  . . . . . . . . . . . . . . . . . . . . .  21
     3.14.  23
     3.15. The Location Claim (location) . . . . . . . . . . . . . .  22
     3.15.  24
     3.16. The Uptime Claim (uptime) . . . . . . . . . . . . . . . .  23
     3.16.  25
     3.17. The Boot Odometer Claim (odometer)  . . . . . . . . . . .  25
     3.18. The Boot Seed Claim (boot-seed) . . . . . . . . . . . . .  23
     3.17.  25
     3.19. The Intended Use Claim (intended-use) . . . . . . . . . .  24
     3.18.  26
     3.20. The Profile Claim (profile) . . . . . . . . . . . . . . .  25
     3.19.  27
     3.21. The DLOA (Digital Letter or Approval) Claim (dloas) . . .  26
     3.20.  27
     3.22. The Software Manifests Claim (manifests)  . . . . . . . .  27
     3.21.  28
     3.23. The Software Evidence Claim (swevidence)  . . . . . . . .  28
     3.22.  30
     3.24. The SW Measurement Results Claim (swresults)  . . . . . .  29
       3.22.1.  30
       3.24.1.  Scheme . . . . . . . . . . . . . . . . . . . . . . .  29
       3.22.2.  31
       3.24.2.  Objective  . . . . . . . . . . . . . . . . . . . . .  30
       3.22.3.  31
       3.24.3.  Results  . . . . . . . . . . . . . . . . . . . . . .  30
       3.22.4.  31
       3.24.4.  Objective Name . . . . . . . . . . . . . . . . . . .  31
     3.23.  32
     3.25. Submodules (submods)  . . . . . . . . . . . . . . . . . .  33
       3.23.1.  34
       3.25.1.  Submodule Types  . . . . . . . . . . . . . . . . . .  33
         3.23.1.1.  34
         3.25.1.1.  Submodule Claims-Set . . . . . . . . . . . . . .  33
         3.23.1.2.  34
         3.25.1.2.  Nested Token . . . . . . . . . . . . . . . . . .  34
         3.23.1.3.  35
         3.25.1.3.  Detached Submodule Digest  . . . . . . . . . . .  36
       3.23.2.  37
       3.25.2.  No Inheritance . . . . . . . . . . . . . . . . . . .  37
       3.23.3.  38
       3.25.3.  Security Levels  . . . . . . . . . . . . . . . . . .  37
       3.23.4.  38
       3.25.4.  Submodule Names  . . . . . . . . . . . . . . . . . .  37
       3.23.5.  39
       3.25.5.  CDDL for submods . . . . . . . . . . . . . . . . . .  38  39
   4.  Unprotected JWT Claims-Sets . . . . . . . . . . . . . . . . .  38  39
   5.  Detached EAT Bundles  . . . . . . . . . . . . . . . . . . . .  39
   6.  Endorsements and Verification Keys  . . . . . . . . . . . . .  40
     6.1.  Identification Methods  . . . . . . . . . . . . . . . . .  41
       6.1.1.  COSE/JWS Key ID . . . . . . . . . . . . . . . . . . .  41
       6.1.2.  JWS and COSE X.509 Header Parameters  . . . . . . . .  41  42
       6.1.3.  CBOR Certificate COSE Header Parameters . . . . . . .  42
       6.1.4.  Claim-Based Key Identification  . . . . . . . . . . .  42
     6.2.  Other Considerations  . . . . . . . . . . . . . . . . . .  42
   7.  Profiles  . . . . . . . . . . . . . . . . . . . . . . . . . .  42  43
     7.1.  Format of a Profile Document  . . . . . . . . . . . . . .  43
     7.2.  List of Profile Issues  . . . . . . . . . . . . . . . . .  43
       7.2.1.  Use of JSON, CBOR or both . . . . . . . . . . . . . .  43
       7.2.2.  CBOR Map and Array Encoding . . . . . . . . . . . . .  43  44
       7.2.3.  CBOR String Encoding  . . . . . . . . . . . . . . . .  44
       7.2.4.  CBOR Preferred Serialization  . . . . . . . . . . . .  44
       7.2.5.  COSE/JOSE Protection  . . . . . . . . . . . . . . . .  44
       7.2.6.  COSE/JOSE Algorithms  . . . . . . . . . . . . . . . .  44  45
       7.2.7.  DEB Support . . . . . . . . . . . . . . . . . . . . .  44  45
       7.2.8.  Verification Key Identification . . . . . . . . . . .  45
       7.2.9.  Endorsement Identification  . . . . . . . . . . . . .  45
       7.2.10. Freshness . . . . . . . . . . . . . . . . . . . . . .  45
       7.2.11. Required Claims . . . . . . . . . . . . . . . . . . .  45
       7.2.12. Prohibited Claims . . . . . . . . . . . . . . . . . .  45
       7.2.13. Additional Claims . . . . . . . . . . . . . . . . . .  45  46
       7.2.14. Refined Claim Definition  . . . . . . . . . . . . . .  45  46
       7.2.15. CBOR Tags . . . . . . . . . . . . . . . . . . . . . .  46
       7.2.16. Manifests and Software Evidence Claims  . . . . . . .  46
   8.  Encoding and Collected CDDL . . . . . . . . . . . . . . . . .  46
     8.1.  Claims-Set and CDDL for CWT and JWT . . . . . . . . . . .  46
     8.2.  Encoding Data Types . . . . . . . . . . . . . . . . . . .  47
       8.2.1.  Common Data Types . . . . . . . . . . . . . . . . . .  47
       8.2.2.  JSON Interoperability . . . . . . . . . . . . . . . .  47
       8.2.3.  Labels  . . . . . . . . . . . . . . . . . . . . . . .  47  48
     8.3.  CBOR Interoperability . . . . . . . . . . . . . . . . . .  48
       8.3.1.  EAT Constrained Device Serialization  . . . . . . . .  48
     8.4.  Collected Common CDDL . . . . . . . . . . . . . . . . . .  49
     8.5.  Collected CDDL for CBOR . . . . . . . . . . . . . . . . .  55  54
     8.6.  Collected CDDL for JSON . . . . . . . . . . . . . . . . .  57  55
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  59  56
     9.1.  Reuse of CBOR and JSON Web Token (CWT and JWT) Claims
           Registries  . . . . . . . . . . . . . . . . . . . . . . .  59  56
     9.2.  Claim Characteristics . . . . . . . . . . . . . . . . . .  59  57
       9.2.1.  Interoperability and Relying Party Orientation  . . .  59  57
       9.2.2.  Operating System and Technology Neutral . . . . . . .  59  57
       9.2.3.  Security Level Neutral  . . . . . . . . . . . . . . .  60  58
       9.2.4.  Reuse of Extant Data Formats  . . . . . . . . . . . .  60  58
       9.2.5.  Proprietary Claims  . . . . . . . . . . . . . . . . .  60  58
     9.3.  Claims Registered by This Document  . . . . . . . . . . .  61  58
       9.3.1.  Claims for Early Assignment . . . . . . . . . . . . .  61  59
       9.3.2.  To be Assigned Claims . . . . . . . . . . . . . . . .  64  62
       9.3.3.  Version Schemes Registered by this Document . . . . .  64  65
       9.3.4.  UEID URN Registered by this Document  . . . . . . . .  64  66
       9.3.5.  Tag for Detached EAT Bundle . . . . . . . . . . . . .  65  66
   10. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  65  66
     10.1.  UEID and SUEID Privacy Considerations  . . . . . . . . .  65  67
     10.2.  Location Privacy Considerations  . . . . . . . . . . . .  66  67
     10.3.  Replay Protection and Privacy  . . . . . . . . . . . . .  68
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  66  68
     11.1.  Key Provisioning . . . . . . . . . . . . . . . . . . . .  66  68
       11.1.1.  Transmission of Key Material . . . . . . . . . . . .  67  69
     11.2.  Transport Security . . . . . . . . . . . . . . . . . . .  67  69
     11.3.  Multiple EAT Consumers . . . . . . . . . . . . . . . . .  67  69
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  68  70
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  68  70
     12.2.  Informative References . . . . . . . . . . . . . . . . .  70  73
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .  73  76
     A.1.  Simple TEE Attestation  . . . . . . . . . . . . . . . . .  73  76
     A.2.  Submodules for Board and Device . . . . . . . . . . . . .  77
     A.3.  EAT Produced by Attestation Hardware Block  . . . . . . .  74
     A.3.  79
     A.4.  Detached EAT Bundle . . . . . . . . . . . . . . . . . . .  75
     A.4.  79
     A.5.  Key / Key Store Attestation . . . . . . . . . . . . . . .  76
     A.5.  81
     A.6.  SW Measurements of an IoT Device  . . . . . . . . . . . .  78
     A.6.  83
     A.7.  Attestation Results in JSON format  . . . . . . . . . . .  81  86
   Appendix B.  UEID Design Rationale  . . . . . . . . . . . . . . .  82  87
     B.1.  Collision Probability . . . . . . . . . . . . . . . . . .  82  87
     B.2.  No Use of UUID  . . . . . . . . . . . . . . . . . . . . .  84  89
   Appendix C.  EAT Relation to IEEE.802.1AR Secure Device Identity
                (DevID)  . . . . . . . . . . . . . . . . . . . . . .  85  90
     C.1.  DevID Used With EAT . . . . . . . . . . . . . . . . . . .  85  90
     C.2.  How EAT Provides an Equivalent Secure Device Identity . .  86  91
     C.3.  An X.509 Format EAT . . . . . . . . . . . . . . . . . . .  86  91
     C.4.  Device Identifier Permanence  . . . . . . . . . . . . . .  87  92
   Appendix D.  Changes from Previous Drafts . . . . . . . . . . . .  87  92
     D.1.  From draft-rats-eat-01  . . . . . . . . . . . . . . . . .  87  92
     D.2.  From draft-mandyam-rats-eat-00  . . . . . . . . . . . . .  87  92
     D.3.  From draft-ietf-rats-eat-01 . . . . . . . . . . . . . . .  87  92
     D.4.  From draft-ietf-rats-eat-02 . . . . . . . . . . . . . . .  88  93
     D.5.  From draft-ietf-rats-eat-03 . . . . . . . . . . . . . . .  88  93
     D.6.  From draft-ietf-rats-eat-04 . . . . . . . . . . . . . . .  88  93
     D.7.  From draft-ietf-rats-eat-05 . . . . . . . . . . . . . . .  89  94
     D.8.  From draft-ietf-rats-eat-06 . . . . . . . . . . . . . . .  89  94
     D.9.  From draft-ietf-rats-eat-07 . . . . . . . . . . . . . . .  89  94
     D.10. From draft-ietf-rats-eat-08 . . . . . . . . . . . . . . .  89  94
     D.11. From draft-ietf-rats-eat-09 . . . . . . . . . . . . . . .  89  94
     D.12. From draft-ietf-rats-eat-10 . . . . . . . . . . . . . . .  90  95
     D.13. From draft-ietf-rats-eat-11 . . . . . . . . . . . . . . .  96
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  91  96

1.  Introduction

   Remote device attestation is

   EAT provides the definition of a fundamental service base set of claims that allows a
   remote device such as a mobile phone, can be made
   about an Internet-of-Things (IoT)
   device, or other endpoint to prove itself to a Relying Party, a
   server or entity, a service. device, some software and/or some hardware.  This allows the Relying Party
   claims set is received by a relying party who uses it to know some
   characteristics about the device and decide whether if
   and how it trusts will interact with the
   device.

   The notion of attestation here is large and remote entity.  It may include, but is not
   limited choose to
   not trust the following:

   o  Proof of the make entity and model of the device hardware (HW)

   o  Proof not interact with it.  It may choose to
   trust it.  It may partially trust it, for example allowing monetary
   transactions only up to a limit.

   EAT defines the encoding of the claims set in CBOR [RFC8949] and JSON
   [RFC7159].  EAT is an extension to CBOR Web Token (CWT) [RFC8392] and
   JSON Web Token (JWT) [RFC7519].

   The claims set is secured in transit with the same mechanisms used by
   CWT and JWT, in particular CBOR Object Signing and Encryption (COSE)
   [RFC8152] and JSON Object Signing and Encryption (JOSE) [RFC7515]
   [RFC7516].  Authenticity and integrity protection must always be
   provided.  Privacy (encryption) may additionally be provided.  The
   key material used to sign and encrypt is specifically created and
   provisioned for the purpose of attestation.  It is the use of this
   key material that make the claims set "attested" rather than just
   some parameters sent to the relying party by the device.

   EAT is focused on authenticating, identifying and characterizing
   implementations where implementations are devices, chips, hardware,
   software and such.  This is distinct from protocols like TLS
   [RFC8446] that authenticate and identify servers and services.  It is
   equally distinct from protocols like SASL [RFC4422] that authenticate
   and identify persons.

   The notion of attestation is large, ranging over a broad variety of
   use cases and security levels.  Here are a few examples of claims:

   o  Make and model of the manufactured consumer device

   o  Make and model of a chip or processor, particularly for a
      security-oriented chips chip

   o  Measurement  Identification and measurement of the software (SW) running on the a device

   o  Configuration and state of the a device

   o  Environmental characteristics of the a device such as like its GPS location

   o  Formal certifications received

   EAT also supports nesting of sets of claims and EAT tokens for use
   with complex composite devices.

   This document uses the terminology and main operational model defined
   in [RATS.Architecture].  In particular particular, it is a format that can be used for RATS
   Attestation Evidence or and Attestation Results as defined in
   the RATS architecture. Results.

1.1.  CWT, JWT, UCCS, UJCS and DEB

   An  Entity Overview

   The document uses the term "entity" to refer to the target of the
   attestation token.  The claims defined in this document are claims
   about an entity.

   An entity is an implementation in hardware, software or both.

   An entity is the same as the Attester Target Environment defined in
   RATS Architecture.

   An entity also corresponds to a "system component" as defined in the
   Internet Security Glossary [RFC4949].  That glossary also defines
   "entity" and "system entity" as something that may be a person or
   organization as well as a system component.  Here "entity" never
   refers to a person or organization.

   An entity is never a server or a service.

   An entity may be the whole device or it may be a subsystem, a
   subsystem of a subsystem and so on.  EAT allows claims to be
   organized into submodules, nested EATs and so on.  See Section 3.25.
   The entity to which a claim applies is the submodule in which it
   appears, or to the top-level entity if it doesn't appear in a set
   submodule.

   Some examples of entities:

   o  A Secure Element

   o  A TEE

   o  A card in a network router

   o  A network router, perhaps with each card in the router a submodule

   o  An IoT device

   o  An individual process

   o  An app on a smartphone

   o  A smartphone with many submodules for its many subsystems

   o  A subsystem in a smartphone like the modem or the camera

   An entity may have strong security like defenses against hardware
   invasive attacks.  It may also have low security, having no special
   security defenses.  There is no minimum security requirement to be an
   entity.

1.2.  CWT, JWT, UCCS, UJCS and DEB

   An EAT is a claims set about an entity/device entity based on one of the following:

   o  CBOR Web Token (CWT), (CWT) [RFC8392]

   o  Unprotected CWT Claims Sets (UCCS), (UCCS) [UCCS.Draft]

   o  JSON Web Token (JWT), (JWT) [RFC7519]

   All definitions, requirements, creation and validation procedures,
   security considerations, IANA registrations and so on from these
   carry over to EAT.

   This specification extends those specifications by defining
   additional claims for attestation.  This specification also describes
   the notion of a "profile" that can narrow the definition of an EAT,
   ensure interoperability and fill in details for specific usage
   scenarios.  This specification also adds some considerations for
   registration of future EAT-related claims.

   The identification of a protocol element as an EAT, whether CBOR or
   JSON encoded, follows the general conventions used by CWT, JWT and
   UCCS.  Largely this depends on the protocol carrying the EAT.  In
   some cases it may be by content type (e.g., MIME type).  In other
   cases it may be through use of CBOR tags.  There is no fixed
   mechanism across all use cases.

   This specification adds two more top-level messages:

   o  Unprotected JWT Claims Set (UJCS), (UJCS) Section 4

   o  Detached EAT Bundle (DEB), Section 5

   A DEB is simple structure to hold a collection of detached claims- claims sets and
   the EAT that separately provides integrity and authenticity
   protection for them.  It can be either CBOR or JSON encoded.

1.2.

1.3.  CDDL, CBOR and JSON

   An EAT can be encoded in either CBOR or JSON.  The definition of each
   claim is such that it can be encoded either.  Each token is either
   entirely CBOR or JSON, with only an exception

   This document defines Concise Binary Object Representation (CBOR)
   [RFC8949] and Javascript Object Notation (JSON) [RFC7159] encoding
   for nested tokens.

   To implement composite attestation as described an EAT.  All claims in an EAT MUST use the RATS
   architecture document, one token has to be nested inside another. same encoding except
   where explicitly allowed.  It is also possible to construct composite Attestation Results (see
   below) which may be expressed as one token explicitly allowed for a nested inside another.  So
   as to not force each end-end attestation system
   token to be all JSON or all
   CBOR, nesting of JSON-encoded tokens in CBOR-encoded tokens a different encoding.  Some claims explicitly contain
   objects and vice
   versa is accommodated by this specification.  This is the only place messages that CBOR and JSON can be mixed. may use a different encoding than the
   enclosing EAT.

   This specification formally uses CDDL, [RFC8610], to define each
   claim. Concise Data Definition Language (CDDL)
   [RFC8610] for all definitions.  The implementor interprets the CDDL
   to come to either the CBOR [RFC8949] or JSON [ECMAScript] representation. encoding.  In the case of JSON,
   Appendix E of [RFC8610] is followed.  Additional rules are given in
   Section 8.2.2 where Appendix E is insufficient.

   The CWT and JWT specifications were authored before CDDL was
   available and did not use CDDL.  This specification includes a CDDL
   definition of most of what is defined in [RFC8392].  Similarly, this
   specification includes CDDL for most of what is defined in [RFC7519].

   The UCCS specification does not include CDDL.  This specification
   provides CDDL for it.

   (TODO: The authors are open to modifications to this specification
   and the UCCS specification to include CDDL for UCCS and UJCS there
   instead of here.)

1.3.

1.4.  Operating Model and RATS Architecture

   While it is not required that EAT be used with the RATS operational
   model described in Figure 1 in [RATS.Architecture], or even that it
   be used for attestation, this document is authored with an
   orientation oriented around that model.

   To summarize, an Attester on an entity/device generates Attestation Evidence.
   Attestation Evidence is a Claims Set claims set describing various
   characteristics of the entity/device. an entity.  Attestation Evidence also is usually
   signed by a key that proves the entity/device entity and the evidence it produces
   are authentic.  The Claims Set claims set includes a nonce or some other means
   to provide freshness.  EAT is designed to carry Attestation Evidence.
   The Attestation Evidence goes to a Verifier where the signature is validated.
   verified.  Some of the Claims claims may also be
   validated checked against Reference
   Values.  The Verifier then produces Attestation Results which is also
   usually a Claims Set. claims set.  EAT is also designed to carry Attestation
   Results.  The Attestation Results go to the Relying Party which is
   the ultimate consumer of the "Remote
   Attestaton Procedures", RATS. Remote Attestation Procedure.  The
   Relying Party uses the Attestation Results as needed for the use
   case, perhaps allowing a device an entity on the network, allowing a financial
   transaction or such.

   Note that sometimes the Verifier and Relying Party are not separate
   and thus there is no need for a protocol to carry Attestation
   Results.

1.3.1.  Use as

1.4.1.  Relationship between Attestation Evidence and Attestation
        Results

   Any claim defined in this document or in the IANA CWT or JWT registry
   may be used in Attestation Evidence. Evidence or Attestation Results.

   Many claims in Attestation Evidence nearly always has simply will pass through the
   Verifier to be signed or otherwise have
   authenticity and integrity protection because the Attester is remote
   relative to the Verifier.  Usually, this is by using COSE/JOSE
   signing where the signing key is an attestation key provisioned into
   the entity/device by its manufacturer.  The details of how this is
   achieved are beyond this specification, but see Section 6.  If there
   is already a suitable secure channel between the Attester and
   Verifier, UCCS may be used.

1.3.2.  Use as Attestation Results

   Any claim defined in this document or in the IANA CWT or JWT registry
   may be used in Attestation Results.

   It is useful to characterize the relationship of claims in Evidence
   to those in Attestation Results.

   Many claims in Attestation Evidence simply will pass through the
   Verifier to the Relying Party without modification.  They will the Relying Party without modification.  They will be
   verified as authentic from the device entity by the Verifier just through
   normal verification of the Attester's signature.  The UEID,
   Section 3.4, and Location, Section 3.14, 3.15, are examples of claims that
   may be passed through.

   Some claims in Attestation Evidence will be verified by the Verifier
   by comparison to Reference Values.  These claims will not likely be
   conveyed to the Relying Party.  Instead, some claim indicating they
   were checked may be added to the Attestation Results or it may be
   tacitly known that the Verifier always does this check.  For example,
   the Verifier receives the Software Evidence claim, Section 3.21, 3.23,
   compares it to Reference Values and conveys the results to the
   Relying Party in a Software Measurement Results Claim, Section 3.22. 3.24.

   In some cases the Verifier may provide privacy-preserving
   functionality by stripping or modifying claims that do not posses
   sufficient privacy-preserving characteristics.  For example, the data
   in the Location claim, Section 3.14, 3.15, may be modified to have a
   precision of a few kilometers rather than a few meters.

   When the Verifier is remote from the Relying Party, the Attestation
   Results must be protected for integrity, authenticity

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and possibly
   confidentiality.  Often
   "OPTIONAL" in this will simply document are to be HTTPS interpreted as per described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This document reuses terminology from JWT [RFC7519] and CWT
   [RFC8392].

   Claim:  A piece of information asserted about a normal web
   service, but COSE subject.  A claim is
      represented as pair with a value and either a name or JOSE may also be used.  The details of this
   protection are beyond the scope of this document.

1.4.  Entity Overview

   An "entity" can be any device or device subassembly ("submodule")
   that can generate its own attestation in the form of an EAT.  The
   attestation should be cryptographically verifiable by the EAT
   consumer.  An EAT at the device-level can be composed of several
   submodule EAT's.

   Modern devices such as a mobile phone have many different execution
   environments operating with different security levels.  For example,
   it is common for a mobile phone to have an "apps" environment that
   runs an operating system (OS) that hosts a plethora of downloadable
   apps.  It may also have a TEE (Trusted Execution Environment) that is
   distinct, isolated, and hosts security-oriented functionality like
   biometric authentication.  Additionally, it may have an eSE (embedded
   Secure Element) - a high security chip with defenses against HW
   attacks that is used to produce attestations.  This device
   attestation format allows the attested data to be tagged at a
   security level from which it originates.  In general, any discrete
   execution environment that has an identifiable security level can be
   considered an entity.

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 JWT [RFC7519] and CWT
   [RFC8392].

   Claim:  A piece of information asserted about a subject.  A claim is
      represented as pair with a value and either a name or key to
      identify it.

   Claim Name:  A unique text string that identifies key to
      identify it.

   Claim Name:  A unique text string that identifies the claim.  It is
      used as the claim name for JSON encoding.

   Claim Key:  The CBOR map key used to identify a claim.

   Claim Value:  The value portion of the claim.  A claim value can be
      any CBOR data item or JSON value.

   CWT/JWT Claims Set:  The CBOR map or JSON object that contains the
      claims conveyed by the CWT or JWT.

   This document reuses terminology from RATS Architecure
   [RATS.Architecture]

   Attester:  A role performed by an entity (typically a device) whose
      Evidence must be appraised in order to infer the extent to which
      the Attester is considered trustworthy, such as when deciding
      whether it is authorized to perform some operation.

   Verifier:  A role that appraises the validity of Attestation Evidence
      about an Attester and produces Attestation Results to be used by a
      Relying Party.

   Relying Party:  A role that depends on the validity of information
      about an Attester, for purposes of reliably applying application
      specific actions.  Compare /relying party/ in [RFC4949].

   Attestation Evidence:  A Claims Set generated by an Attester to be
      appraised by a Verifier.  Attestation Evidence may include
      configuration data, measurements, telemetry, or inferences.

   Attestation Results:  The output generated by a Verifier, typically
      including information about an Attester, where the Verifier
      vouches for the validity of the results

   Reference Values:  A set of values against which values of Claims can
      be compared as part of applying an Appraisal Policy for
      Attestation Evidence.  Reference Values are sometimes referred to
      in other documents as known-good values, golden measurements, or
      nominal values, although those terms typically assume comparison
      for equality, whereas here Reference Values might be more general
      and be used in any sort of comparison.

3.  The Claims

   This section describes new claims defined for attestation that are to
   be added to the CWT [IANA.CWT.Claims] and JWT [IANA.JWT.Claims] IANA
   registries.

   This section also describes how several extant CWT and JWT claims
   apply in EAT.

   CDDL, along with a text description, is used to define each claim
   independent of encoding.  Each claim is defined as a CDDL group.  In
   Section 8 on encoding, the CDDL groups turn into CBOR map entries and
   JSON name/value pairs.

   Each claim described has a unique text string and integer that
   identifies it.  CBOR encoded tokens MUST use only the integer for
   Claim Keys.  JSON encoded tokens MUST use only the text string for
   Claim Names.

3.1.  Token ID Claim (cti and jti)

   CWT defines the "cti" claim.  JWT defines the "jti" claim.  These are
   equivalent to each other in EAT and carry a unique token identifier
   as they do in JWT and CWT.  They may be used to defend against re use
   of the token but are distinct from the nonce that is used by the
   Relying Party to guarantee freshness and defend against replay.

3.2.  Timestamp claim (iat)

   The "iat" claim defined in CWT and JWT is used to indicate the date-
   of-creation of the token, the time at which the claims are collected
   and the token is composed and signed.

   The data for some claims may be held or cached for some period of
   time before the token is created.  This period may be long, even
   days.  Examples are measurements taken at boot or a geographic
   position fix taken the last time a satellite signal was received.
   There are individual timestamps associated with these claims to
   indicate their age is older than the "iat" timestamp.

   CWT allows the use floating-point for this claim.  EAT disallows the
   use of floating-point.  No  An EAT token may MUST NOT contain an iat claim in float-
   point
   float-point format.  Any recipient of a token with a floating-point
   format iat claim may MUST consider it an error.  A 64-bit integer
   representation of epoch time can represent a range of +/- 500 billion
   years, so the only point of a floating-point timestamp is to have
   precession greater than one second.  This is not needed for EAT.

3.3.  Nonce Claim (nonce)

   All EATs should have a nonce to prevent replay attacks.  The nonce is
   generated by the Relying Party, the end consumer of the token.  It is
   conveyed to the entity over whatever transport is in use before the
   token is generated and then included in the token as the nonce claim.

   This documents the nonce claim for registration in the IANA CWT
   claims registry.  This is equivalent to the JWT nonce claim that is
   already registered.

   The nonce must be at least 8 bytes (64 bits) long as fewer bytes are
   unlikely to be secure.  A maximum of 64 bytes is set to limit the
   memory a constrained implementation uses.  This size range is not set
   for the already-registered JWT nonce, but it should follow this size
   recommendation when used in an EAT.

   Multiple nonces are allowed to accommodate multistage verification
   and consumption.

   $$claims-set-claims //=
       (nonce-label => nonce-type / [ 2* nonce-type ])

   nonce-type = bstr .size (8..64)

3.4.  Universal Entity ID Claim (ueid)

   UEID's identify

   A UEID identifies an individual manufactured entities / devices such as entity like a mobile
   phone, a water meter, a Bluetooth speaker or a networked security
   camera.  It may identify the entire device entity or a submodule or
   subsystem. submodule.  It does
   not identify types, models or classes of devices. entities.  It is akin to a
   serial number, though it does not have to be sequential.

   UEID's must

   UEIDs MUST be universally and globally unique across manufacturers
   and countries.  UEIDs must MUST also be unique across protocols and
   systems, as tokens are intended to be embedded in many different
   protocols and systems.  No two products anywhere, even in completely
   different industries made by two different manufacturers in two
   different countries should have the same UEID (if they are not global
   and universal in this way, then Relying Parties receiving them will
   have to track other characteristics of the device entity to keep devices entities
   distinct between manufacturers).

   There are privacy considerations for UEID's. UEIDs.  See Section 10.1.

   The UEID is permanent.  It MUST never change for a given device / entity.

   UEIDs are variable length.  All implementations MUST be able to
   receive UEIDs that are 33 bytes long (1 type byte and 256 bits).  The
   recommended maximum sent is also 33 bytes.

   When the entity constructs the UEID, the first byte

   A UEID is constructed of a single type and byte followed by the
   following bytes the ID for
   that type. are the identifier.  Several types are allowed to accommodate
   different industries and industries, different manufacturing processes and to give options to avoid have
   an alternative that doesn't require paying fees for certain types
   of manufacturer registrations. a registration fee.

   Creation of new types requires a Standards Action [RFC8126].

   UEIDs are variable length.  All implementations MUST be able to
   receive UEIDs that are 33 bytes long (1 type byte and 256 bits).  No
   UEID longer than 33 bytes SHOULD be sent.

   +------+------+-----------------------------------------------------+
   | Type | Type | Specification                                       |
   | Byte | Name |                                                     |
   +------+------+-----------------------------------------------------+
   | 0x01 | RAND | This is a 128, 192 or 256 bit 256-bit random number         |
   |      |      | generated once and stored in the device. entity. This may   |
   |      |      | be constructed by concatenating enough identifiers  |
   |      |      | to make up an equivalent number of random bits and  |
   |      |      | then feeding the concatenation through a            |
   |      |      | cryptographic hash function. It may also be a       |
   |      |      | cryptographic quality random number generated once  |
   |      |      | at the beginning of the life of the device entity and      |
   |      |      | stored. It may not MUST NOT be smaller than 128 bits. See   |
   |      |      | the length analysis in Appendix B.                  |
   | 0x02 | IEEE | This makes use of uses the IEEE company identification registry. |
   |      | EUI  | registry. An EUI is either an EUI-48, EUI-60 or EUI-64 and    |
   |      |      | EUI-64 and made up of an OUI, OUI-36 or a CID, different       |
   |      |      | different registered company identifiers, and some unique     |
   |      |      | unique per-device per-entity identifier. EUIs are often the same as   |
   |      |      | same as or similar to MAC addresses. This type includes     |
   |      |      | includes MAC-48, an obsolete name for EUI-48. (Note that     |
   |      |      | that while devices entities with multiple network interfaces may |
   |      |      | may have multiple MAC addresses, there is only one UEID |
   |      |      | UEID for a device) an entity) [IEEE.802-2001], [OUI.Guide] [OUI.Guide].        |
   | 0x03 | IMEI | This is a 14-digit identifier consisting of an      |
   |      |      | 8-digit Type Allocation Code and a 6-digit serial   |
   |      |      | number allocated by the manufacturer, which SHALL   |
   |      |      | be encoded as byte string of length 14 with each    |
   |      |      | byte as the digit's value (not the ASCII encoding   |
   |      |      | of the digit; the digit 3 encodes as 0x03, not      |
   |      |      | 0x33). The IMEI value encoded SHALL NOT include     |
   |      |      | Luhn checksum or SVN information. [ThreeGPP.IMEI] See               |
   |      |      | [ThreeGPP.IMEI].                                    |
   +------+------+-----------------------------------------------------+

                      Table 1: UEID Composition Types

   UEID's

   UEIDs are not designed for direct use by humans (e.g., printing on
   the case of a device), so no textual representation is defined.

   The consumer (the Relying Party) of a UEID MUST treat a UEID as a
   completely opaque string of bytes and not make any use of its
   internal structure.  For example, they should not use the OUI part of
   a type 0x02 UEID to identify the manufacturer of the device.  Instead entity.
   Instead, they should use the oemid claim that is defined elsewhere. OEMID claim.  See Section 3.6.  The
   reasons for this are:

   o  UEIDs types may vary freely from one manufacturer to the next.

   o  New types of UEIDs may be created.  For example, a type 0x07 UEID
      may be created based on some other manufacturer registration
      scheme.

   o  Device  Entity manufacturers are allowed to change from one type of UEID
      to another anytime they want.  For example, they may find they can
      optimize their manufacturing by switching from type 0x01 to type
      0x02 or vice versa.  The main essential requirement on the manufacturer
      is that UEIDs be universally unique.

   A Device Indentifier Identifier URN is registered for UEIDs.  See Section 9.3.4.

   $$claims-set-claims //= (ueid-label => ueid-type)

   ueid-type = bstr .size (7..33)

3.5.  Semi-permanent UEIDs (SUEIDs)

   An SEUID is of the same format as a UEID, but it may MAY change to a
   different value on device life-cycle events.  Examples of these
   events are change of ownership, factory reset and on-boarding into an
   IoT device management system.  A device may  An entity MAY have both a UEID and
   SUEIDs, neither, one or the other.

   There may MAY be multiple SUEIDs.  Each one has a text string label the
   purpose of which is to distinguish it from others in the token.  The
   label may MAY name the purpose, application or type of the SUEID.
   Typically, there will be few SUEDs so there is no need for a formal
   labeling mechanism like a registry.  The EAT profile may MAY describe how
   SUEIDs should be labeled.  If there is only one SUEID, the claim
   remains a map and there still must be a label.  For example, the
   label for the SUEID used by FIDO Onboarding Protocol could simply be
   "FDO".

   There are privacy considerations for SUEID's. SUEIDs.  See Section 10.1.

   A Device Indentifier URN is registered for SUEIDs.  See
   Section 9.3.4.

   $$claims-set-claims //= (sueids-label => sueids-type)

   sueids-type = {
       + tstr => ueid-type
   }

3.6.  Hardware OEM Identification (oemid)

   This claim identifies the OEM Original Equipment Manufacturer (OEM) of
   the hardware.  Any of the three forms may described below MAY be used at
   the convenience of the attester implementation. claim sender.  The receiver of this claim MUST
   be able to handle all three forms.

3.6.1.  Random Number Based

   This format is OEMID

   The random number based OEMID MUST always 16 bytes in size (128 bits).

   The OEM may MAY create their own ID by using a cryptographic-quality
   random number generator.  They would perform this only once in the
   life of the company to generate the single ID for said company.  They
   would use that same ID in every device entity they make.  This uniquely
   identifies the OEM on a statistical basis and is large enough should
   there be ten billion companies.

   The OEM may MAY also use a hash function like SHA-256 and truncate the
   output to 128 bits.  The input to the hash should be somethings that
   have at least 96 bits of entropy, but preferably 128 bits of entropy.
   The input to the hash may MAY be something whose uniqueness is managed by
   a central registry like a domain name.

   This is to

   In JSON format tokens this MUST be base64url encoded in JSON. encoded.

3.6.2.  IEEE Based OEMID

   The IEEE operates a global registry for MAC addresses and company
   IDs.  This claim uses that database to identify OEMs.  The contents
   of the claim may be either an IEEE MA-L, MA-M, MA-S or an IEEE CID
   [IEEE.RA].  An MA-L, formerly known as an OUI, is a 24-bit value used
   as the first half of a MAC address.  MA-M similarly is a 28-bit value
   uses as the first part of a MAC address, and MA-S, formerly known as
   OUI-36, a 36-bit value.  Many companies already have purchased one of
   these.  A CID is also a 24-bit value from the same space as an MA-L,
   but not for use as a MAC address.  IEEE has published Guidelines for
   Use of EUI, OUI, and CID [OUI.Guide] and provides a lookup services service
   [OUI.Lookup].

   Companies that have more than one of these IDs or MAC address blocks
   should pick
   SHOULD select one and prefer that for all their devices. entities.

   Commonly, these are expressed in Hexadecimal Representation
   [IEEE.802-2001] as
   described in [IEEE.802-2001].  It is also called the Canonical
   format.  When this claim is encoded the order of bytes in the bstr
   are the same as the order in the Hexadecimal Representation.  For
   example, an MA-L like "AC-DE-48" would be encoded in 3 bytes with
   values 0xAC, 0xDE, 0x48.  For JSON
   encoded tokens, this is further base64url encoded.

   This format is always 3 bytes in size in CBOR.

   In JSON format tokens, this MUST be base64url encoded and always 4
   bytes.

3.6.3.  IANA Private Enterprise Number Based OEMID

   IANA maintains a simple integer-based company registry called the Private
   Enterprise Number (PEN) [PEN].

   PENs are often used to create an OID.  That is not the case here.
   They are used only as a simple an integer.

   In CBOR this is value MUST be encoded as a major type 0 integer in CBOR and is
   typically 3 bytes.  It is  In JSON, this value MUST be encoded as a number in JSON. number.

   oemid-pen = int

   oemid-ieee = bstr .size 3

   oemid-random = bstr .size 16

   $$claims-set-claims //= (
       oemid-label =>
           oemid-random / oemid-ieee / oemid-pen
   )

3.7.  Hardware Version Claims (hardware-version-claims)

   The Model Claim (hardware-model)

   This claim differentiates hardware version can be claimed at three different levels, models, products and variants
   manufactured by a particular OEM, the
   chip, one identified by OEM ID in
   Section 3.6.

   This claim must be unique so as to differentiate the circuit board models and
   products for the final device assembly.  An EAT OEM ID.  This claim does not have to be globally
   unique, but it can
   include any combination these claims.

   The hardware version be.  A receiver of this claim MUST not assume it
   is globally unique.  To globally identify a simple text string particular product, the format
   receiver should concatenate the OEM ID and this claim.

   The granularity of which the model identification is
   set by for each manufacturer. OEM to
   decide.  It may be very granular, perhaps including some version
   information.  It may be very general, perhaps only indicating top-
   level products.

   The structure purpose of this claim is to identify models within protocols, not
   for human-readable descriptions.  The format and sorting order encoding of this
   text string can
   claim should not be specified using the version-scheme item human-readable to discourage use other than in
   protocols.  If this claim is to be derived from
   CoSWID [CoSWID].

   The hardware version an already-in-use
   human-readable identifier, it can also be given by run through a 13-digit [EAN-13].  A new
   CoSWID version scheme hash function.

   There is registered no minimum length so that an OEM with IANA by this document in
   Section 9.3.3. a very small number of
   models can use a one-byte encoding.  The maximum length is 32 bytes.
   All receivers of this claim MUST be able to receive this maximum
   size.

   The receiver of this claim MUST treat it as a completely opaque
   string of bytes, even if there is some apparent naming or structure.
   The OEM is free to alter the internal structure of these bytes as
   long as the claim continues to uniquely identify its models.

   hardware-model-type = bytes .size (1..32)

   $$claims-set-claims //= (
       hardware-model-label => hardware-model-type
   )

3.8.  Hardware Version Claims (hardware-version-claims)

   The hardware version is a text string the format of which is set by
   each manufacturer.  The structure and sorting order of this text
   string can be specified using the version-scheme item from CoSWID
   [CoSWID].  It is useful to know how to sort versions so the newer can
   be distinguished from the older.

   The hardware version can also be given by a 13-digit [EAN-13].  A new
   CoSWID version scheme is registered with IANA by this document in
   Section 9.3.3.  An EAN-13 is also known as an International Article
   Number or most commonly as a bar code.

   $$claims-set-claims //=  (
       chip-version-label => hw-version-type
   )

   $$claims-set-claims //=  (
       board-version-label => hw-version-type
   )

   $$claims-set-claims //=  (
       device-version-label
       hardware-version-label => hw-version-type hardware-version-type
   )

   hw-version-type

   hardware-version-type = [
       version:  tstr,
       scheme:  $version-scheme
   ]

3.8.

3.9.  Software Name Claim

   This is a simple free-form text claim for the name of the software. software for the
   entity or submodule.  A CoSWID manifest or other type of manifest can
   be used instead if this claim is too simple. to limited to correctly characterize
   the SW for the entity or submodule.

   $$claims-set-claims //= ( sw-name-label => tstr )

3.9.

3.10.  Software Version Claim

   This makes use of the CoSWID version scheme data type to give a
   simple version for the software.  A full CoSWID manifest or other
   type of manifest can be instead if this is too simple.

   $$claims-set-claims //= (sw-version-label => sw-version-type)

   sw-version-type = [
       version:  tstr,
       scheme:  $version-scheme / ; As defined by CoSWID /
   ]

3.10.

3.11.  The Security Level Claim (security-level)

   This claim characterizes the device/entity entity's ability to defend against
   attacks aimed at capturing the signing key, forging claims and at
   forging EATs.  This is by defining four security levels as described
   below.

   These claims describe levels.

   This claim describes the security environment and countermeasures
   available on the end-entity/client device entity where the attestation key resides and the
   claims originate.

   1 - Unrestricted:  There is some expectation that implementor will
      protect the attestation signing keys at this level.  Otherwise,
      the EAT provides no meaningful security assurances.

   2 - Restricted:  Entities at this level are not general-purpose
      operating environments that host features features, such as app download
      systems, web browsers and complex productivity applications.  It is akin to the
      secure-restricted level (see below) without the security
      orientation.  Examples include a Wi-Fi subsystem, an IoT camera,
      or sensor device.  Often these can be considered more secure than
      unrestricted just because they are much simpler and a smaller
      attack surface, but this won't always be the case.  Some
      unrestricted devices may be implemented in a way that provides
      poor protection of signing keys.

   3 - Secure-Restricted:  Entities at this level must meet the criteria
      defined in section Section 4 of FIDO Allowed Restricted Operating
      Environments [FIDO.AROE].  Examples include TEE's and schemes
      using virtualization-based security.  Like the FIDO security goal,
      security  Security at this level is
      aimed at defending well against large-
      scale large-scale network/remote attacks
      against the device. entity.

   4 - Hardware:  Entities at this level must include substantial
      defense against physical or electrical attacks against the device entity
      itself.  It is assumed any the potential attacker has captured the
      device
      entity and can disassemble it.  Examples include TPMs and Secure
      Elements.

   The entity should claim the highest security level it achieves and no
   higher.  This set is not extensible so as to provide a common
   interoperable description of security level to the Relying Party.  If
   a particular implementation use case considers this claim to be inadequate, it can
   define its own proprietary claim.  It may consider including both
   this claim as a coarse indication of security and its own proprietary
   claim as a refined indication.

   This claim is not intended as a replacement for a proper end-device formal security
   certification scheme scheme, such as those based on FIPS 140 [FIPS-140] or
   those based on Common Criteria [Common.Criteria].  The
   claim made here is solely a self-claim made by the Attester.  See Section 3.21.

   $$claims-set-claims //= (
       security-level-label =>
           security-level-cbor-type /
           security-level-json-type
   )

   security-level-cbor-type = &(
       unrestricted: 1,
       restricted: 2,
       secure-restricted: 3,
       hardware: 4
   )

   security-level-json-type =
       "unrestricted" /
       "restricted" /
       "secure-restricted" /
       "hardware"

3.11.

3.12.  Secure Boot Claim (secure-boot)

   The value of true indicates secure boot is enabled.  Secure boot is
   considered enabled when base software, the firmware and operating system, are under
   control of the entity manufacturer identified of the entity identified in the OEMID
   claim described in Section 3.6.  This may because  Control by the
   software is in ROM or because manufacturer of the
   firmware and the operating system may be by it is being in ROM, being
   cryptographically authenticated
   or some authenticated, a combination of the two or other. similar.

   $$claims-set-claims //= (secure-boot-label => bool)

3.12.

3.13.  Debug Status Claim (debug-status)

   This applies to system-wide entity-wide or submodule-wide debug facilities of the
   target device / submodule
   entity like JTAG and diagnostic hardware built into chips.  It
   applies to any software debug facilities related to root, operating
   system or privileged software that allow system-wide memory
   inspection, tracing or modification of non-system software like user
   mode applications.

   This characterization assumes that debug facilities can be enabled
   and disabled in a dynamic way or be disabled in some permanent way
   such that no enabling is possible.  An example of dynamic enabling is
   one where some authentication is required to enable debugging.  An
   example of permanent disabling is blowing a hardware fuse in a chip.
   The specific type of the mechanism is not taken into account.  For
   example, it does not matter if authentication is by a global password
   or by per-device per-entity public keys.

   As with all claims, the absence of the debug level claim means it is
   not reported.  A conservative interpretation might assume the Not
   Disabled enabled
   state.  It could however be that it is reported in a
   proprietary claim.

   This claim is not extensible so as to provide a common interoperable
   description of debug status to the Relying Party. status.  If a particular implementation
   considers this claim to be inadequate, it can define its own
   proprietary claim.  It may consider including both this claim as a
   coarse indication of debug status and its own proprietary claim as a
   refined indication.

   The higher levels of debug disabling requires that all debug
   disabling of the levels below it be in effect.  Since the lowest
   level requires that all of the target's debug be currently disabled,
   all other levels require that too.

   There is no inheritance of claims from a submodule to a superior
   module or vice versa.  There is no assumption, requirement or
   guarantee that the target of a superior module encompasses the
   targets of submodules.  Thus, every submodule must explicitly
   describe its own debug state.  The Verifier or Relying Party
   receiving receiver of an EAT cannot MUST not assume
   that debug is turned off in a submodule because there is a claim
   indicating it is turned off in a superior module.

   An individual target device / submodule entity may have multiple debug facilities.  The use of plural in
   the description of the states refers to that, not to any aggregation
   or inheritance.

   The architecture of some chips or devices may be such that a debug
   facility operates for the whole chip or device.  If the EAT for such
   a chip includes submodules, then each submodule should independently
   report the status of the whole-chip or whole-device debug facility.
   This is the only way the Relying Party receiver can know the debug status of the
   submodules since there is no inheritance.

3.12.1.

3.13.1.  Enabled

   If any debug facility, even manufacturer hardware diagnostics, is
   currently enabled, then this level must be indicated.

3.12.2.

3.13.2.  Disabled

   This level indicates all debug facilities are currently disabled.  It
   may be possible to enable them in the future, and it future.  It may also be
   possible that
   they were enabled in the past after the target device/
   sub-system booted/started, past, but they are currently disabled.

3.12.3.

3.13.3.  Disabled Since Boot

   This level indicates all debug facilities are currently disabled and
   have been so since the target device/sub-system entity booted/started.

3.12.4.

3.13.4.  Disabled Permanently

   This level indicates all non-manufacturer facilities are permanently
   disabled such that no end user or developer cannot can enable them.  Only
   the manufacturer indicated in the OEMID claim can enable them.  This
   also indicates that all debug facilities are currently disabled and
   have been so since boot/start.

3.12.5.

3.13.5.  Disabled Fully and Permanently

   This level indicates that all debug capabilities facilities for the target
   device/sub-module entity are
   permanently disabled.

   $$claims-set-claims //=  (
       debug-status-label =>
           debug-status-cbor-type / debug-status-json-type
   )

   debug-status-cbor-type = &(
       enabled: 0,
       disabled: 1,
       disabled-since-boot: 2,
       disabled-permanently: 3,
       disabled-fully-and-permanently: 4
   )

   debug-status-json-type =
       "enabled" /
       "disabled" /
       "disabled-since-boot" /
       "disabled-permanently" /
       "disabled-fully-and-permanently"

3.13.

3.14.  Including Keys

   An EAT may include a cryptographic key such as a public key.  The
   signing of the EAT binds the key to all the other claims in the
   token.

   The purpose for inclusion of the key may vary by use case.  For
   example, the key may be included as part of an IoT device onboarding
   protocol.  When the FIDO protocol includes a pubic public key in its
   attestation message, the key represents the binding of a user, device
   and Relying Party.  This document describes how claims containing
   keys should be defined for the various use cases.  It does not define
   specific claims for specific use cases.

   Keys in CBOR format tokens SHOULD be the COSE_Key format [RFC8152]
   and keys in JSON format tokens SHOULD be the JSON Web Key format
   [RFC7517].  These two formats support many common key types.  Their
   use avoids the need to decode other serialization formats.  These two
   formats can be extended to support further key types through their
   IANA registries.

   The general confirmation claim format [RFC8747], [RFC7800] may also
   be used.  It provides key encryption.  It also allows for inclusion
   by reference through a key ID.  The confirmation claim format may
   employed in the definition of some new claim for a a particular use
   case.

   When the actual confirmation claim is included in an EAT, this
   document associates no use case semantics other than proof of
   posession.
   possession.  Different EAT use cases may choose to associate further
   semantics.  The key in the confirmation claim MUST be protected in
   the same way as the key used to sign the EAT.  That is, the same,
   equivalent or better hardware defenses, access controls, key
   generation and such must be used.

3.14.

3.15.  The Location Claim (location)

   The location claim gives the location of the device entity from which the
   attestation originates.  It is derived from the W3C Geolocation API
   [W3C.GeoLoc].  The latitude, longitude, altitude and accuracy must
   conform to [WGS84].  The altitude is in meters above the [WGS84]
   ellipsoid.  The two accuracy values are positive numbers in meters.
   The heading is in degrees relative to true north.  If the device entity is
   stationary, the heading is NaN (floating-point not-a-number).  The
   speed is the horizontal component of the device entity velocity in meters
   per second.

   When encoding floating-point numbers half-precision should not SHOULD NOT be
   used.  It  They usually does do not provide enough precision for a geographic
   location.  It is not a requirement that the receiver of an EAT
   implement half-precision, so the receiver may not be able to decode
   the location.

   The location may have been cached for a period of time before token
   creation.  For example, it might have been minutes or hours or more
   since the last contact with a GPS satellite.  Either the timestamp or
   age data item can be used to quantify the cached period.  The
   timestamp data item is preferred as it a non-relative time.

   The age data item can be used when the entity doesn't know what time
   it is either because it doesn't have a clock or it isn't set.  The
   entity must MUST still have a "ticker" that can measure a time interval.
   The age is the interval between acquisition of the location data and
   token creation.

   See location-related privacy considerations in Section 10.2 below. 10.2.

   $$claims-set-claims //= (location-label => location-type)

   location-type = {
       latitude => number,
       longitude => number,
       ? altitude => number,
       ? accuracy => number,
       ? altitude-accuracy => number,
       ? heading => number,
       ? speed => number,
       ? timestamp => ~time-int,
       ? age => uint
   }

   latitude = 1 / "latitude"
   longitude = 2 / "longitude"
   altitude = 3 / "altitude"
   accuracy = 4 / "accuracy"
   altitude-accuracy = 5 / "altitude-accuracy"
   heading = 6 / "heading"
   speed = 7 / "speed"
   timestamp = 8 / "timestamp"
   age = 9 / "age"

3.15.

3.16.  The Uptime Claim (uptime)

   The "uptime" claim contains MUST contain a value that represents the number of
   seconds that have elapsed since the entity or submod was last booted.

   $$claims-set-claims //= (uptime-label => uint)

3.16.

3.17.  The Boot Odometer Claim (odometer)

   The "odometer" claim contains a value that represents the number of
   times the entity or submod has been booted.  Support for this claim
   requires a persistent storage on the device.

   $$claims-set-claims //= (odometer-label => uint)

3.18.  The Boot Seed Claim (boot-seed)

   The Boot Seed claim is MUST contain a random value created at system
   boot time that will allow differentiation of reports from different
   boot sessions.

   This value is usually public and not protected. public.  It is not
   the same as a seed secret and MUST NOT be
   used for any purpose that a secret seed is needed, such as seeding a
   random number generator which must be kept
   secret. generator.

   $$claims-set-claims //=  (boot-seed-label => bytes)

3.17.

3.19.  The Intended Use Claim (intended-use)

   EAT's may be used in the context of several different applications.
   The intended-use claim provides an indication to an EAT consumer
   about the intended usage of the token.  This claim can be used as a
   way for an application using EAT to internally distinguish between
   different ways it uses EAT.

   1 - Generic Generic:  Generic attestation describes an application where the
      EAT consumer requres requires the most up-to-date security assessment of
      the attesting entity.  It is expected that this is the most
      commonly-used application of EAT.

   2- Registration Registration:  Entities that are registering for a new service may
      be expected to provide an attestation as part of the registration
      process.  This intended-use setting indicates that the attestation
      is not intended for any use but registration.

   3 - Provisioning Provisioning:  Entities may be provisioned with different values
      or settings by an EAT consumer.  Examples include key material or
      device management trees.  The consumer may require an EAT to
      assess device entity security state of the entity prior to provisioning.

   4 - Certificate Issuance (Certificate Signing Request)  Certifying
      authorities  Certification Authorities (CA's) may
      require attestations prior to the issuance of certificates related
      to keypairs hosted at the entity.  An EAT may be used as part of
      the certificate signing request (CSR).

   5 - Proof-of-Possession Proof-of-Possession:  An EAT consumer may require an attestation
      as part of an accompanying proof-of-possession (PoP) appication. application.
      More precisely, a PoP transaction is intended to provide to the
      recipient cryptographically-verifiable proof that the sender has
      posession
      possession of a key.  This kind of attestation may be neceesary necceesary
      to verify the security state of the entity storing the private key
      used in a PoP application.

   $$claims-set-claims //= (
       intended-use-label =>
           intended-use-cbor-type / intended-use-json-type
   )

   intended-use-cbor-type = &(
       generic: 1,
       registration: 2,
       provisioning: 3,
       csr: 4,
       pop: 5
   )

   intended-use-json-type =
       "generic" /
       "registration" /
       "provisioning" /
       "csr" /
       "pop"

3.18.

3.20.  The Profile Claim (profile)

   See Section 7 for the detailed description of a profile.

   A profile is identified by either a URL or an OID.  Typically, the
   URI will reference a document describing the profile.  An OID is just
   a unique identifier for the profile.  It may exist anywhere in the
   OID tree.  There is no requirement that the named document be
   publicly accessible.  The primary purpose of the profile claim is to
   uniquely identify the profile even if it is a private profile.

   The OID is encoded in always absolute and never relative.  In CBOR tokens, the
   OID MUST be encoded according to [CBOR.OID] [RFC9090] and the URI according to
   [RFC8949].  Both are unwrapped and thus not CBOR tags.  The
   OID is always absolute and never relative.  If  In JSON
   tokens, the claims CBOR type OID is a text string it is a URI of the form "X.X.X", and if a byte string it URI is an OID. a
   normal URI string.

   Note that this is named "eat_profile" for JWT and is distinct from
   the already registered "profile" claim in the JWT claims registry.

   $$claims-set-claims //= (profile-label => ~uri / ~oid)

   oid = #6.4000(bstr) ; TODO: Replace with CDDL from OID RFC

3.19.

3.21.  The DLOA (Digital Letter or Approval) Claim (dloas)

   A DLOA (Digital Letter of Approval) [DLOA] is an XML document that
   describes a certification that a device or an entity has received.  Examples of
   certifications represented by a DLOA include those issued by Global
   Platform and those based on Common Criteria.  The DLOA is unspecific
   to any particular certification type or those issued by any
   particular organization.

   This claim is typically issued by a Verifier, not an Attester.  When
   this claim is issued by a Verifier, it MUST be because the entity,
   device or submodule entity has
   received the certification in the DLOA.

   This claim can MAY contain more than one DLOA.  If multiple DLOAs are
   present, it MUST be because the entity, device or submodule entity received all of the
   certifications.

   DLOA XML documents are always fetched from a registrar that stores
   them.  This claim contains several data items used to construct a URL
   for fetching the DLOA from the particular registrar.

   This claim MUST be encoded as an array with either two or three
   elements.  The first data item is a element MUST be the URI for the registrar.  The
   second data item
   is element MUST be a platform label to indicate the particular indicating which platform that was
   certified.  For platform certifications only these two are needed.

   A  If the DLOA may equally apply applies to an application.  In that case it has the
   URI for application, then the registrar, a platform label and additionally third
   element is added which MUST be an application label.  The method of combining
   constructing the registrar URI, platform label and possibly
   application label is specified in [DLOA].

   $$claims-set-claims //= (
       dloas-label => [ + dloa-type ]
   )

   dloa-type = [
       dloa_registrar: ~uri
       dloa_platform_label: text
       ? dloa_application_label: text
   ]

3.20.

3.22.  The Software Manifests Claim (manifests)

   This claim contains descriptions of software that is present on the
   device. entity.
   These manifests are installed on the device entity when the software is
   installed or are created as part of the installation process.
   Installation is anything that adds software to the device, entity, possibly
   factory installation, the user installing elective applications and
   so on.  The defining characteristic is that they are created by the
   software manufacturer.  The purpose of these claims in an EAT is to
   relay them without modification to the Verifier and/or and possibly to the
   Relying Party.

   In some cases these will

   Some manifests may be signed by the their software manufacturer
   independent of any signing for the purpose of before
   they are put into this EAT attestation.
   Manifest claims should include claim.  When such manifests are put into
   this claim, the manufacturer's signature (which
   will SHOULD be included.  For
   example, the manifest might be a CoSWID signed over by the attestation signature).  In other cases software
   manufacturer, in which case the attestation signature will full signed CoSWID should be the only one. put in
   this claim.

   This claim allows multiple formats for the manifest.  For example example,
   the manifest may be a CBOR-format CoSWID, an XML-format SWID or
   other.  Identification of the type of manifest is always by a CBOR
   tag.  In many cases, for examples CoSWID, a tag will already be
   registered with IANA.  If not, a tag MUST be registered.  It can be
   in the first-come-first-served space which has minimal requirements
   for registration.

   The claim is an array of one or more manifests.  To facilitate hand
   off of the manifest to a decoding library, each manifest is contained
   in a byte string.  This occurs for CBOR-format manifests as well as
   non-CBOR format manifests.

   If a particular manifest type uses CBOR encoding, then the item in
   the array for it MUST be a byte string that contains a CBOR tag.  The
   EAT decoder must decode the byte string and then the CBOR within it
   to find the tag number to identify the type of manifest.  The
   contents of the byte string is then handed to the particular manifest
   processor for that type of manifest.  CoSWID and SUIT manifest are
   examples of this.

   If a particular manifest type does not use CBOR encoding, then the
   item in the array for it must MUST be a CBOR tag that contains a byte
   string.  The EAT decoder uses the tag to identify the processor for
   that type of manifest.  The contents of the tag, the byte string, are
   handed to the manifest processor.  Note that a byte string is used to
   contain the manifest whether it is a text based format or not.  An
   example of this is an XML format ISO/IEC 19770 SWID.

   It is not possible to describe the above requirements in CDDL CDDL, so the
   type for an individual manifest is any in the CDDL below.  The above
   text sets the encoding requirement.

   This claim allows for multiple manifests in one token since multiple
   software packages are likely to be present.  The multiple manifests
   may
   MAY be of multiple formats.  In some cases EAT submodules may be used
   instead of the array structure in this claim for multiple manifests.

   When the [CoSWID] format is used, it MUST be a payload CoSWID, not an
   evidence CoSWID.

   $$claims-set-claims //= (
       manifests-label => manifests-type
   )

   manifests-type = [+ $$manifest-formats]

   ; Must be a CoSWID payload type
   ; TODO: signed CoSWIDs

   coswid-that-is-a-cbor-tag-xx = tagged-coswid<concise-swid-tag>

   $$manifest-formats /= bytes .cbor coswid-that-is-a-cbor-tag-xx

   ; TODO: make this work too
   ;$$manifest-formats /= bytes .cbor SUIT_Envelope_Tagged

3.21.

3.23.  The Software Evidence Claim (swevidence)

   This claim contains descriptions, lists, evidence or measurements of
   the software that exists on the device. entity.  The defining characteristic
   of this claim is that its contents are created by processes on the
   device
   entity that inventory, measure or otherwise characterize the software
   on the device. entity.  The contents of this claim do not originate from the
   software manufacturer.

   In most cases

   This claim uses the contents same mechanism for identification of this claim are signed as part of
   attestation signing, but independent signing in addition to the
   attestation signing is not ruled out when a particular evidence
   format supports it.

   This claim uses the same mechanism for identification of the type the type of
   the swevidence as is used for the type of the manifest in the
   manifests claim.  It also uses the same byte string based mechanism
   for containing the claim and easing the hand off to a processing
   library.  See the discussion above in the manifests claim.

   When the [CoSWID] format is used, it MUST be evidence CoSWIDs, not
   payload CoSWIDS.

   $$claims-set-claims //= (
       swevidence-label => swevidence-type
   )

   swevidence-type = [+ $$swevidence-formats]

   ; Must be a CoSWID evidence type that is a CBOR tag
   ; TODO: fix the CDDL so a signed CoSWID is allowed too

   coswid-that-is-a-cbor-tag = tagged-coswid<concise-swid-tag>
   $$swevidence-formats /= bytes .cbor coswid-that-is-a-cbor-tag

3.22.

3.24.  The SW Measurement Results Claim (swresults)

   This claims reports the outcome of the comparison of a measurement on
   some software to the expected Reference Values.  It may report a
   successful comparison, failed comparison or other.

   This claim may MAY be generated by the Verifier and sent to the Relying
   Party.  For example, it could be the results of the Verifier
   comparing the contents of the swevidence claim to Reference Values.

   This claim can MAY also be generated on the device entity if the device entity has the
   ability for one subsystem to measure another subsystem.  For example,
   a TEE might have the ability to measure the software of the rich OS
   and may have the Reference Values for the rich OS.

   Within an attestation target or submodule, multiple results can be
   reported.  For example, it may be desirable to report the results for
   the kernel and each individual application separately.

   For each software objective, the following can be reported.

3.22.1.  TODO:
   defined objective

3.24.1.  Scheme

   This is the free-form text name of the verification system or scheme
   that performed the verification.  There is no official registry of
   schemes or systems.  It may be the name of a commercial product or
   such.

3.22.2.

3.24.2.  Objective

   This roughly characterizes the coverage of the software measurement
   software.  This corresponds to the attestation target or the
   submodule.  If all of the indicated target is not covered, the
   measurement must indicate partial.

   1 - all all:  Indicates all the software has been verified, for example,
      all the software in the attestation target or the submodule

   2 - firmware firmware:  Indicates all of and only the firmware

   3 - kernel kernel:  Refers to all of the most-privileged software, for
      example the Linux kernel

   4 - privileged privileged:  Refers to all of the software used by the root,
      system or administrative account

   5 - system-libs system-libs:  Refers to all of the system libraries that are
      broadly shared and used by applications and such

   6 - partial partial:  Some other partial set of the software

3.22.3.

3.24.3.  Results

   This describes the result of the measurement and also the comparison
   to Reference Values.

   1 - verificaton-not-run verification-not-run:  Indicates that no attempt was made to run
      the verification

   2 - verification-indeterminite verification-indeterminite:  The verification was attempted, but
      it did not produce a result; perhaps it ran out of memory, the
      battery died or such

   3 - verification-failed verification-failed:  The verification ran to completion, the
      comparison was completed and did not compare correctly to the
      Reference Values

   4 - fully-verified fully-verified:  The verification ran to completion and all
      measurements compared correctly to Reference Values

   5 - partially-verified partially-verified:  The verification ran to completion and some,
      but not all all, measurements compared correctly to Reference Values

3.22.4.

3.24.4.  Objective Name

   This is a free-form text string that describes the objective.  For
   example, "Linux kernel" or "Facebook App"
   $$claims-set-claims //= (swresults-label => [ + swresult-type ])

   verification-result-cbor-type = &(
       verification-not-run: 1,
       verification-indeterminate: 2,
       verification-failed: 3,
       fully-verified: 4,
       partially-verified: 5,
   )

   verification-result-json-type =
       "verification-not-run" /
       "verification-indeterminate" /
       "verification-failed" /
       "fully-verified" /
       "partially-verified"

   verification-objective-cbor-type = &(
       all: 1,
       firmware: 2,
       kernel: 3,
       privileged: 4,
       system-libs: 5,
       partial: 6,
   )

   verification-objective-json-type =
       "all" /
       "firmware" /
       "kernel" /
       "privileged" /
       "system-libs" /
       "partial"

   swresult-type = [
       verification-system: tstr,
       objective: verification-objective-cbor-type /
           verification-objective-json-type,
       result: verification-result-cbor-type /
           verification-result-json-type,
       ? objective-name: tstr
   ]

3.23.

3.25.  Submodules (submods)

   Some devices are complex, having many subsystems.  A mobile phone is
   a good example.  It may have several connectivity subsystems for
   communications (e.g., Wi-Fi and cellular).  It may have subsystems
   for low-power audio and video playback.  It may have one or more multiple
   security-oriented subsystems like a TEE or and a Secure Element.

   The claims for a subsystem can be grouped together in a submodule or
   submod.

   The submods are in a single map/object, one entry per submodule.
   There is only one submods map/object in a token.  It is identified by
   its specific label.  It is a peer to other claims, but it is not
   called a claim because it is a container for a claims set rather than
   an individual claim.  This submods part of a token allows what might
   be called recursion.  It allows claims sets inside of claims sets
   inside of claims sets...

3.23.1.

3.25.1.  Submodule Types

   The following sections define the three major types of submodules:

   o  A submodule Claims-Set

   o  A nested token, which can be any valid EAT token, CBOR or JSON

   o  The digest of a detached Claims-Set

   These are distinguished primarily by their data type which may be a
   map/object, string or array.

3.23.1.1.

3.25.1.1.  Submodule Claims-Set

   This is simply a subordinate Claims-Set containing claims about the
   submodule.

   The submodule claims-set is produced by the same Attester as the
   surrounding token.  It is secured using the same mechanism as the
   enclosing token (e.g., it is signed by the same attestation key).  It
   roughly corresponds to an Attester Target Environment Environment, as described
   in the RATS architecture.

   It may contain claims that are the same as its surrounding token or
   superior submodules.  For example, the top-level of the token may
   have a UEID, a submod may have a different UEID and a further
   subordinate submodule may also have a UEID.

   The encoding of a submodule Claims-Set is always MUST be the same as the
   encoding as the token it is part of.

   This data type for this type of submodule is a map/object as that map/object.  It is
   the
   identified when decoding by it's type of being a Claims-Set.

3.23.1.2. map/object.

3.25.1.2.  Nested Token

   This type of submodule is a fully formed complete token.  It is
   typically produced by a separate Attester.  It is typically used by a
   Composite Device as described in RATS Architecture
   [RATS.Architecture] In being a submodule of the surrounding token, it
   is cryptographically bound to the surrounding token.  If it was
   conveyed in parallel with the surrounding token, there would be no
   such binding and attackers could substitute a good attestation from
   another device for the attestation of an errant subsystem.

   A nested token does NOT not need to use the same encoding as the
   enclosing token.  This is to allow Composite Devices to be built
   without regards to the encoding supported by their Attesters.  Thus a
   CBOR-encoded token like a CWT or UCCS can have a JWT as a nested
   token submodule and a JSON-encoded token can have a CWT or UCCS as a
   nested token submodule.

   The data type for this type of submodule is either following two sections describe how to encode and decode a text or byte
   string.

   Mechanisms are defined for identifying nested
   token.

3.25.1.2.1.  Surrounding EAT is CBOR-Encoded

   This describes the encoding and type decoding of the
   nested token.  These mechanisms are different for CBOR and JSON
   encoding.  The type of or JSON-encoded
   tokens nested inside a CBOR-encoded token.

   If the nested token is identified
   using the CBOR-encoded, then it MUST be a CBOR tagging mechanism tag and thus
   MUST be wrapped in a byte string.  The tag identifies whether the
   nested token is a CWT, a UCCS, a CBOR-encoded DEB, or some other
   CBOR-format token defined in common with
   identification used when any the future.  A nested CBOR-encoded token
   that is part of not a CBOR-
   based protocol.  A new simple type mechanism CBOR tag is defined for
   indication of NOT allowed.

   If the type of a JSON-encoded nested token since there is no JSON
   equivalent of tagging.

3.23.1.2.1.  Surrounding EAT is CBOR-Encoded

   If the submodule is a byte string, JSON-encoded, then the nested token is CBOR-
   encoded. data item MUST be a
   text string.  The byte text string always wraps a token that is MUST contain a tag. JSON-encoded array of
   two items.  The
   tag identifies whether the nested token first item is a CWT, a UCCS or a CBOR-
   encoded DEB.

   If string identifying the submodule is a text string, then type of the nested token
   token.  The second item is JSON-
   encoded. the JSON-encoded token.

   The text string contains JSON.  That JSON is identifying the exactly JSON-encoded token MUST be one of the JSON described
   following:

   "JWT":  The second item MUST be a JWT formatted according to
      [RFC7519]

   "UJCS":  The second item MUST be a UJCS-Message as defined in the next section with one exception. this
      document.

   "DEB":  The token
   can't second item MUST be CBOR-encoded.

   ; This specifies how one fully-formed token a JSON-encoded Detached EAT Bundle as
      defined in this document.

   The definition of additional types requires a standards action.

   When decoding, if a byte string is nested inside encountered, it is known to be a
   ; CBOR-format
   nested CBOR-encoded token.  The fully-formed nested token byte string wrapping is any valid
   ; token, CBOR or JSON (JWT, CWT, UCCS, DEB...) removed.  The mechanism for
   ; identifying the
   type of the nested token is specific to the format
   ; of determined by the surrounding token, CBOR in this case.
   ;
   ; A primary reason this tag.

   When decoding, if a text string is encoding-specific encountered, it is that JSON does not
   ; have an equivalent known to CBOR tags.
   ;
   ; If the data type here is text, then the nested token is JSON
   ; format, one of be a JWT, UJCS or
   JSON-encoded DEB. token.  The means for
   ; distinguishing which two-item array is in the definition of JSON-encoded
   ; Nested-Token.  If decoded and tells the data type is bstr, then
   of the nested token
   ; is CBOR format. It is byte-string wrapped and identified by a
   ;CBOR tag. JSON-encoded token.

   Nested-Token =
       tstr / ; A JSON-encoded Nested-Token (see json-nested-token.cddl)
       bstr .cbor Tagged-CBOR-Token

3.23.1.2.2.

3.25.1.2.2.  Surrounding EAT is JSON-Encoded

   A

   This describes the encoding and decoding of CBOR or JSON-encoded
   tokens nested token in inside a JSON-encoded token.

   The nested token is MUST be an array of two items.  The
   first is in the same format as
   described in the section above.

   A CBOR-encoded token nested inside a string that indicates JSON-encoded MUST use the type same
   array of two, but with the second item type as follows:

   "JWT"  A JWT formatted according to [RFC7519]

   "CBOR"

   "CBOR":  Some base64url-encoded CBOR that is a tag that is either tag, typically a CWT,
      UCCS or CBOR-encoded DEB

   "UJCS"  A UJCS-Message.  (A UJCS-Message

   When decoding, the array of two is identical to a JSON-
      encoded Claims-Set)

   "DEB"  A JSON-encoded Detached EAT Bundle.

   ; This describes a decoded.  The first item indicates
   the type and encoding of the nested token that occurs inside a JSON-encoded
   ; token. It uses an array that  If the type string is made up not
   "CBOR", then the token is JSON-encoded and of a the type indicator and indicated by
   the
   ; actual token.  This string.

   If the type string is a substitute for "CBOR", then the token is CBOR-encoded.  The
   base64url encoding is removed.  The CBOR-encoded data is then
   decoded.  The type of nested token is determined by the CBOR-tag.  It
   is an error if the CBOR tag mechanism that
   ; JSON does is not have. a tag.

   Nested-Token = [
      type : "JWT" / "CBOR" / "UJCS" / "DEB",
      nested-token : JWT-Message /
                     B64URL-Tagged-CBOR-Token /
                     DEB-JSON-Message /
                     UJCS-Message
   ]

   ; This text is a Tagged-CBOR-Token (see cbor-token.cddl) that is
   ; base64url encoded.  For example, it is a CWT that is a COSE_Sign1
   ; that is a CBOR tag that has been base64url encoded.

   B64URL-Tagged-CBOR-Token = tstr .regexp "[A-Za-z0-9_=-]+"

3.23.1.3.

3.25.1.3.  Detached Submodule Digest

   This is type of submodule equivalent to a Claims-Set submodule,
   except the Claims-Set is conveyed separately outside of the token.

   This type of submodule consists of a digest made using a
   cryptographic hash of a Claims-Set.  The Claims-Set is not included
   in the token.  It is conveyed to the Verifier outside of the token.
   The submodule containing the digest is called a detached digest.  The
   separately conveyed Claims-Set is called a detached claims set.

   The input to the digest is exactly the byte-string wrapped encoded
   form of the Claims-Set for the submodule.  That Claims-Set can
   include other submodules including nested tokens and detached
   digests.

   The primary use for this is to facilitate the implementation of a
   small and secure attester, perhaps purely in hardware.  This small,
   secure attester implements COSE signing and only a few claims,
   perhaps just UEID and hardware identification.  It has inputs for
   digests of submodules, perhaps 32-byte hardware registers.  Software
   running on the device constructs larger claim sets, perhaps very
   large, encodes them and digests them.  The digests are written into
   the small secure attesters registers.  The EAT produced by the small
   secure attester only contains the UEID, hardware identification and
   digests and is thus simple enough to be implemented in hardware.
   Probably, every data item in it is of fixed length.

   The integrity protection for the larger Claims Sets will not be as
   secure as those originating in hardware block, but the key material
   and hardware-based claims will be.  It is possible for the hardware
   to enforce hardware access control (memory protection) on the digest
   registers so that some of the larger claims can be more secure.  For
   example, one register may be writable only by the TEE, so the
   detached claims from the TEE will have TEE-level security.

   The data type for this type of submodule is MUST be an array It contains
   two data items, an algorithm identifier and a byte string containing
   the digest.

   A DEB, described in Section 5, may be used to convey detached claims
   sets and the

   When decoding a CBOR format token the detached digest type is
   distringuished from the other types by it being an array.  In CBOR
   the none of other submodule types are arrays.

   When decoding a JSON format token, a little more work is required
   because both the nested token and detached digest types are an array.
   To distinguish the nested token from the detached digest, the first
   element in the array is examined.  If it is "JWT", "UJCS" or "DEB",
   the the submodule is a nested token.  Otherwise it will contain an
   algorithm identifier and is a detached digest.

   A DEB, described in Section 5, may be used to convey detached claims
   sets and the token with their detached digests.  EAT, however,
   doesn't require use of a DEB.  Any other protocols may be used to
   convey detached claims sets and the token with their detached
   digests.  Note that since detached Claims-Sets are usually signed,
   protocols conveying them must make sure they are not modified in
   transit.

3.23.2.

3.25.2.  No Inheritance

   The subordinate modules do not inherit anything from the containing
   token.  The subordinate modules must explicitly include all of their
   claims.  This is the case even for claims like the nonce.

   This rule is in place for simplicity.  It avoids complex inheritance
   rules that might vary from one type of claim to another.

3.23.3.

3.25.3.  Security Levels

   The security level of the non-token subordinate modules should always
   be less than or equal to that of the containing modules in the case
   of non-token submodules.  It makes no sense for a module of lesser
   security to be signing claims of a module of higher security.  An
   example of this is a TEE signing claims made by the non-TEE parts
   (e.g. the high-level OS) of the device.

   The opposite may be true for the nested tokens.  They usually have
   their own more secure key material.  An example of this is an
   embedded secure element.

3.23.4.

3.25.4.  Submodule Names

   The label or name for each submodule in the submods map is a text
   string naming the submodule.  No submodules may have the same name.

3.23.5.

3.25.5.  CDDL for submods

   ; This

   The submodule type is distinguished in the part of encoded bytes by its data
   type, map/object for a Claims-Set, string for nested token that contains all the submodules.  It
   ; is and array
   for a peer with the claims detached submodule.  Nested tokens are byte-string wrapped when
   encoded in the token, but not a claim, only a
   ; map/object to hold all the submodules. CBOR and base64 encoded for JSON.

   $$claims-set-claims //= (submods-label => { + text => Submodule })

   ; A submodule can be:
   ; - A simple

   Submodule = Claims-Set (encoded in the same format as the token)
   ; - A / Nested-Token / Detached-Submodule-Digest

   Detached-Submodule-Digest = [
      algorithm : int / text,
      digest : bstr
   ]

4.  Unprotected JWT Claims-Sets

   This is simply the JSON equivalent of a detached an Unprotected CWT Claims-Set (encoded in
   [UCCS.Draft].

   It has no protection of its own so protections must be provided by
   the same format as
   ;    the token)
   ; - A nested token which may be either CBOR or JSON format. Further,
   ;   the mechanism for identifying and containing the nested token
   ;   depends on the format of the surrounding token, particularly
   ;   because JSON doesn't have any equivalent of a CBOR tag so a
   ;   JSON-specific mechanism is invented. Also, there is the issue
   ;   that binary data must be B64 encoded when carried in
   ;   JSON. Nested-Token is defined in the format specific CDDL, not
   ;   here.

   ; Note that at nested token can either be a signed token like a CWT
   ; or JWT, an unsigned token like a UCCS or UJCS, or a DEB (detached
   ; EAT bundle).  The specific encoding of these is format-specific
   ; so it doesn't appear here.

   Submodule = Claims-Set / Nested-Token / Detached-Submodule-Digest

   ; This is for both JSON and CBOR.  JSON uses text label for
   ; algorithm from JOSE registry. CBOR uses integer label for
   ; algorithm from COSE registry. In JSON the digest is base64
   ; encoded.

   Detached-Submodule-Digest = [
      algorithm : int / text,
      digest : bstr
   ]

4.  Unprotected JWT Claims-Sets

   This is simply the JSON equivalent of an Unprotected CWT Claims-Set
   [UCCS.Draft].

   It has no protection of its own so protections must be provided by
   the protocol carrying it.  These are extensively discussed in
   [UCCS.Draft].  All protocol carrying it.  These are extensively discussed in
   [UCCS.Draft].  All the security discussion and security
   considerations in [UCCS.Draft] apply to UJCS.

   (Note: The EAT author is open to this definition being moved into the
   UCCS draft, perhaps along with the related CDDL.  It is place here
   for now so that the current UCCS draft plus this document are
   complete.  UJCS is needed for the same use cases that a UCCS is
   needed.  Further, JSON will commonly be used to convey Attestation
   Results since JSON is common for server to server communications.
   Server to server communications will often have established security
   (e.g., TLS) therefore the signing and encryption from JWS and JWE are
   unnecssary and burdensome).

5.  Detached EAT Bundles

   A detached EAT bundle is a structure to convey a fully-formed and
   signed token plus detached claims set that relate to that token.  It
   is a top-level EAT message like a CWT, JWT, UCCS and UJCS.  It can be
   used any place that CWT, JWT, UCCS or UJCS messages are used.  It may
   also be sent as a submodule.

   A DEB has two main parts.

   The first part is a full top-level token.  This top-level token must
   have at least one submodule that is a detached digest.  This top-
   level token may be either CBOR or JSON-encoded.  It may be a CWT,
   JWT, UCCS or UJCS, but not a DEB.  The same mechanism for
   distinguishing the type for nested token submodules is used here.

   The second part is a map/object containing the detached Claims-Sets
   corresponding to the detached digests in the full token.  When the
   DEB is CBOR-encoded, each Claims-Set is wrapped in a byte string.
   When the DEB is JSON-encoded, each Claims-Set is base64url encoded.
   All the detached Claims-Sets MUST be encoded in the same format as
   the DEB.  No mixing of encoding formats is allowed for the Claims-
   Sets in a DEB.

   For CBOR-encoded DEBs, tag TBD602 can be used to identify it.  The
   normal rules apply for use or non-use of a tag.  When it is sent as a
   submodule, it is always sent as a tag to distinguish it from the
   other types of nested tokens.

   The digests of the detached claims sets are associated with detached
   claims-sets by label/name.  It is up to the constructor of the
   detached EAT bundle to ensure the names uniquely identify the
   detached claims sets.  Since the names are used only in the detached
   EAT bundle, they can be very short, perhaps one byte.

   ; Top-level definition of a DEB for CBOR and JSON

   Detached-EAT-Bundle = [
       main-token : Nested-Token,
       detached-claims-sets: {
           + tstr => cbor-wrapped-claims-set / json-wrapped-claims-set
       }
   ]

   ; text content is a base64url encoded JSON-format Claims-Set

   json-wrapped-claims-set = tstr .regexp "[A-Za-z0-9_=-]+"

   cbor-wrapped-claims-set = bstr .cbor Claims-Set

6.  Endorsements and Verification Keys

   The Verifier must possess the correct key when it performs the
   cryptographic part of an EAT verification (e.g., verifying the COSE/
   JOSE signature).  This section describes several ways to identify the
   verification key.  There is not one standard method.

   The verification key itself may be a public key, a symmetric key or
   something complicated in the case of a scheme like Direct Anonymous
   Attestation (DAA).

   RATS Architecture [RATS.Architecture] describes what is called an
   Endorsement.  This is an input to the Verifier that is usually the
   basis of the trust placed in an EAT and the Attester that generated
   it.  It may contain the public key for verification of the signature
   on the EAT.  It may contain Reference Values to which EAT claims are
   compared as part of the verification process.  It may contain implied
   claims, those that are passed on to the Relying Party in Attestation
   Results.

   There is not yet any standard format(s) for an Endorsement.  One
   format that may be used for an Endorsement is an X.509 certificate.
   Endorsement data like Reference Values and implied claims can be
   carried in X.509 v3 extensions.  In this use, the public key in the
   X.509 certificate becomes the verification key, so identification of
   the Endorsement is also identification of the verification key.

   The verification key identification and establishment of trust in the
   EAT and the attester may also be by some other means than an
   Endorsement.

   For the components (Attester, Verifier, Relying Party,...) of a
   particular end-end attestation system to reliably interoperate, its
   definition should specify how the verification key is identified.
   Usually, this will be in the profile document for a particular
   attestation system.

6.1.  Identification Methods

   Following is a list of possible methods of key identification.  A
   specific attestation system may employ any one of these or one not
   listed here.

   The following assumes Endorsements are X.509 certificates or
   equivalent and thus does not mention or define any identifier for
   Endorsements in other formats.  If such an Endorsement format is
   created, new identifiers for them will also need to be created.

6.1.1.  COSE/JWS Key ID

   The COSE standard header parameter for Key ID (kid) may be used.  See
   [RFC8152] and [RFC7515]

   COSE leaves the semantics of the key ID open-ended.  It could be a
   record locator in a database, a hash of a public key, an input to a
   KDF, an authority key identifier (AKI) for an X.509 certificate or
   other.  The profile document should specify what the key ID's
   semantics are.

6.1.2.  JWS and COSE X.509 Header Parameters

   COSE X.509 [COSE.X509.Draft] and JSON Web Siganture [RFC7515] define
   several header parameters (x5t, x5u,...) for referencing or carrying
   X.509 certificates any of which may be used.

   The X.509 certificate may be an Endorsement and thus carrying
   additional input to the Verifier.  It may be just an X.509
   certificate, not an Endorsement.  The same header parameters are used
   in both cases.  It is up to the attestation system design and the
   Verifier to determine which.

6.1.3.  CBOR Certificate COSE Header Parameters

   Compressed X.509 and CBOR Native certificates are defined by CBOR
   Certificates [CBOR.Cert.Draft].  These are semantically compatible
   with X.509 and therefore can be used as an equivalent to X.509 as
   described above.

   These are identified by their own header parameters (c5t, c5u,...).

6.1.4.  Claim-Based Key Identification

   For some attestation systems, a claim may be re-used as a key
   identifier.  For example, the UEID uniquely identifies the device entity and
   therefore can work well as a key identifier or Endorsement
   identifier.

   This has the advantage that key identification requires no additional
   bytes in the EAT and makes the EAT smaller.

   This has the disadvantage that the unverified EAT must be
   substantially decoded to obtain the identifier since the identifier
   is in the COSE/JOSE payload, not in the headers.

6.2.  Other Considerations

   In all cases there must be some way that the verification key is
   itself verified or determined to be trustworthy.  The key
   identification itself is never enough.  This will always be by some
   out-of-band mechanism that is not described here.  For example, the
   Verifier may be configured with a root certificate or a master key by
   the Verifier system administrator.

   Often an X.509 certificate or an Endorsement carries more than just
   the verification key.  For example, an X.509 certificate might have
   key usage constraints and an Endorsement might have Reference Values.
   When this is the case, the key identifier must be either a protected
   header or in the payload such that it is cryptographically bound to
   the EAT.  This is in line with the requirements in section 6 on Key
   Identification in JSON Web Signature [RFC7515].

7.  Profiles

   This EAT specification does not gaurantee that implementations of it
   will interoperate.  The variability in this specification is
   necessary to accommodate the widely varying use cases.  An EAT
   profile narrows the specification for a specific use case.  An ideal
   EAT profile will guarantee interoperability.

   The profile can be named in the token using the profile claim
   described in Section 3.18. 3.20.

   A profile can apply to Attestation Evidence or to Attestation Results
   or both.

7.1.  Format of a Profile Document

   A profile document doesn't have to be in any particular format.  It
   may be simple text, something more formal or a combination.

   In some cases CDDL may be created that replaces CDDL in this or other
   document to express some profile requirements.  For example, to
   require the altitude data item in the location claim, CDDL can be
   written that replicates the location claim with the altitude no
   longer optional.

7.2.  List of Profile Issues

   The following is a list of EAT, CWT, UCCS, JWS, UJCS, COSE, JOSE and
   CBOR options that a profile should address.

7.2.1.  Use of JSON, CBOR or both

   The profile should indicate whether the token format should be CBOR,
   JSON, both or even some other encoding.  If some other encoding, a
   specification for how the CDDL described here is serialized in that
   encoding is necessary.

   This should be addressed for the top-level token and for any nested
   tokens.  For example, a profile might require all nested tokens to be
   of the same encoding of the top level token.

7.2.2.  CBOR Map and Array Encoding

   The profile should indicate whether definite-length arrays/maps,
   indefinite-length arrays/maps or both are allowed.  A good default is
   to allow only definite-length arrays/maps.

   An alternate is to allow both definite and indefinite-length arrays/
   maps.  The decoder should accept either.  Encoders that need to fit
   on very small hardware or be actually implement in hardware can use
   indefinite-length encoding.

   This applies to individual EAT claims, CWT and COSE parts of the
   implementation.

7.2.3.  CBOR String Encoding

   The profile should indicate whether definite-length strings,
   indefinite-length strings or both are allowed.  A good default is to
   allow only definite-length strings.  As with map and array encoding,
   allowing indefinite-length strings can be beneficial for some smaller
   implementations.

7.2.4.  CBOR Preferred Serialization

   The profile should indicate whether encoders must use preferred
   serialization.  The profile should indicate whether decoders must
   accept non-preferred serialization.

7.2.5.  COSE/JOSE Protection

   COSE and JOSE have several options for signed, MACed and encrypted
   messages.  EAT/CWT has the option to have no protection using UCCS
   and JOSE has a NULL protection option.  It is possible to implement
   no protection, sign only, MAC only, sign then encrypt and so on.  All
   combinations allowed by COSE, JOSE, JWT, CWT, UCCS and UJCS are
   allowed by EAT.

   The profile should list the protections that must be supported by all
   decoders implementing the profile.  The encoders them must implement
   a subset of what is listed for the decoders, perhaps only one.

   Implementations may choose to sign or MAC before encryption so that
   the implementation layer doing the signing or MACing can be the
   smallest.  It is often easier to make smaller implementations more
   secure, perhaps even implementing in solely in hardware.  The key
   material for a signature or MAC is a private key, while for
   encryption it is likely to be a public key.  The key for encryption
   requires less protection.

7.2.6.  COSE/JOSE Algorithms

   The profile document should list the COSE algorithms that a Verifier
   must implement.  The Attester will select one of them.  Since there
   is no negotiation, the Verifier should implement all algorithms
   listed in the profile.  If detached submodules are used, the COSE
   algorithms allowed for their digests should also be in the profile.

7.2.7.  DEB Support

   A Detatched EAT Bundle Section 5 is a special case message that will
   not often be used.  A profile may prohibit its use.

7.2.8.  Verification Key Identification

   Section Section 6 describes a number of methods for identifying a
   verification key.  The profile document should specify one of these
   or one that is not described.  The ones described in this document
   are only roughly described.  The profile document should go into the
   full detail.

7.2.9.  Endorsement Identification

   Similar to, or perhaps the same as Verification Key Identification,
   the profile may wish to specify how Endorsements are to be
   identified.  However note that Endorsement Identification is
   optional, where as key identification is not.

7.2.10.  Freshness

   Just about every use case will require some means of knowing the EAT
   is recent enough and not a replay of an old token.  The profile
   should describe how freshness is achieved.  The section on Freshness
   in [RATS.Architecture] describes some of the possible solutions to
   achieve this.

7.2.11.  Required Claims

   The profile can list claims whose absence results in Verification
   failure.

7.2.12.  Prohibited Claims

   The profile can list claims whose presence results in Verification
   failure.

7.2.13.  Additional Claims

   The profile may describe entirely new claims.  These claims can be
   required or optional.

7.2.14.  Refined Claim Definition

   The profile may lock down optional aspects of individual claims.  For
   example, it may require altitude in the location claim, or it may
   require that HW Versions always be described using EAN-13.

7.2.15.  CBOR Tags

   The profile should specify whether the token should be a CWT Tag or
   not.  Similarly, the profile should specify whether the token should
   be a UCCS tag or not.

   When COSE protection is used, the profile should specify whether COSE
   tags are used or not.  Note that RFC 8392 requires COSE tags be used
   in a CWT tag.

   Often a tag is unncessary because the surrounding or carrying
   protocol identifies the object as an EAT.

7.2.16.  Manifests and Software Evidence Claims

   The profile should specify which formats are allowed for the
   manifests and software evidence claims.  The profile may also go on
   to say which parts and options of these formats are used, allowed and
   prohibited.

8.  Encoding and Collected CDDL

   An EAT is fundamentally defined using CDDL.  This document specifies
   how to encode the CDDL in CBOR or JSON.  Since CBOR can express some
   things that JSON can't (e.g., tags) or that are expressed differently
   (e.g., labels) there is some CDDL that is specific to the encoding
   format.

8.1.  Claims-Set and CDDL for CWT and JWT

   CDDL was not used to define CWT or JWT.  It was not available at the
   time.

   This document defines CDDL for both CWT and JWT as well as UCCS.
   This document does not change the encoding or semantics of anything
   in a CWT or JWT.

   A Claims-Set is the central data structure for EAT, CWT, JWT and
   UCCS.  It holds all the claims and is the structure that is secured
   by signing or other means.  It is not possible to define EAT, CWT,
   JWT or UCCS in CDDL without it.  The CDDL definition of Claims-Set
   here is applicable to EAT, CWT, JWT and UCCS.

   This document specifies how to encode a Claims-Set in CBOR or JSON.

   With the exception of nested tokens and some other externally defined
   structures (e.g., SWIDs) an entire Claims-Set must be in encoded in
   either CBOR or JSON, never a mixture.

   CDDL for the seven claims defined by [RFC8392] and [RFC7519] is
   included here.

8.2.  Encoding Data Types

   This makes use of the types defined in [RFC8610] Appendix D, Standard
   Prelude.

8.2.1.  Common Data Types

   time-int is identical to the epoch-based time, but disallows
   floating-point representation.

   Unless expliclity indicated, URIs are not the URI tag defined in
   [RFC8949].  They are just text strings that contain a URI.

   string-or-uri = tstr

   time-int = #6.1(int)

8.2.2.  JSON Interoperability

   JSON should be encoded per [RFC8610] Appendix E.  In addition, the
   following CDDL types are encoded in JSON as follows:

   o  bstr - must be base64url encoded

   o  time - must be encoded as NumericDate as described section 2 of
      [RFC7519].

   o  string-or-uri - must be encoded as StringOrURI as described
      section 2 of [RFC7519].

   o  uri - must be a URI [RFC3986].

   o  oid - encoded as a string using the well established dotted-
      decimal notation (e.g., the text "1.2.250.1").

8.2.3.  Labels

   Map labels, including Claims-Keys and Claim-Names, and enumerated-
   type values are always integers when encoding in CBOR and strings
   when encoding in JSON.  There is an exception to this for naming
   submodules and detached claims sets in a DEB.  These are strings in
   CBOR.

   The CDDL in most cases gives both the integer label and the string
   label as it is not convenient to have conditional CDDL for such.

8.3.  CBOR Interoperability

   CBOR allows data items to be serialized in more than one form.  If
   the sender uses a form that the receiver can't decode, there will not
   be interoperability.

   This specification gives no blanket requirements to narrow CBOR
   serialization for all uses of EAT.  This allows individual uses to
   tailor serialization to the environment.  It also may result in EAT
   implementations that don't interoperate.

   One way to guarantee interoperability is to clearly specify CBOR
   serialization in a profile document.  See Section 7 for a list of
   serialization issues that should be addressed.

   EAT will be commonly used where the device entity generating the attestation
   is constrained and the receiver/Verifier of the attestation is a
   capacious server.  Following is a set of serialization requirements
   that work well for that use case and are guaranteed to interoperate.
   Use of this serialization is recommended where possible, but not
   required.  An EAT profile may just reference the following section
   rather than spell out serialization details.

8.3.1.  EAT Constrained Device Serialization

   o  Preferred serialization described in section 4.1 of [RFC8949] is
      not required.  The EAT decoder must accept all forms of number
      serialization.  The EAT encoder may use any form it wishes.

   o  The EAT decoder must accept indefinite length arrays and maps as
      described in section 3.2.2 of [RFC8949].  The EAT encoder may use
      indefinite length arrays and maps if it wishes.

   o  The EAT decoder must accept indefinite length strings as described
      in section 3.2.3 of [RFC8949].  The EAT encoder may use indefinite
      length strings if it wishes.

   o  Sorting of maps by key is not required.  The EAT decoder must not
      rely on sorting.

   o  Deterministic encoding described in Section 4.2 of [RFC8949] is
      not required.

   o  Basic validity described in section 5.3.1 of [RFC8949] must be
      followed.  The EAT encoder must not send duplicate map keys/labels
      or invalid UTF-8 strings.

8.4.  Collected Common CDDL

   ; This is the fundamental definition of a Claims-Set for both CBOR
   ; and JSON. It is a set of label-value pairs each of which is a
   ; claim.
   ;
   ; In CBOR the labels can be integers or strings with a strong
   ; preference for integers.  For JSON, the labels are always strings.
   ;
   ; The values can be anything, with some consideration for types that
   ; can work in both CBOR and JSON.

Claims-Set = {
    * $$claims-set-claims,
    * Claim-Label .feature "extended-label" => any
}

Claim-Label = int / text
string-or-uri = tstr

time-int = #6.1(int)
   ; This is CDDL for the 7 individual claims that are defined in CWT
   ; and JWT.  This CDDL works for either CBOR format CWT or JSON format
   ; JWT The integer format CWT Claim Keys (the labels) are defined in
   ; cwt-labels.cddl.  The string format JWT Claim Names (the labels)
   ; are defined in jwt-labels.cddl.

   ; $$claims-set-claims is defined in claims-set.cddl
$$claims-set-claims //= (iss-label => text)
$$claims-set-claims //= (sub-label => text)
$$claims-set-claims //= (aud-label => text)
$$claims-set-claims //= (exp-label => ~time)
$$claims-set-claims //= (nbf-label => ~time)
$$claims-set-claims //= (iat-label => ~time)

   ; TODO: how does the bstr get handled in JSON validation with the
   ; cddl tool?  TODO: should this be a text for JSON?
   ; $$claims-set-claims //= (cti-label : bytes)

$$claims-set-claims //=
    (nonce-label => nonce-type / [ 2* nonce-type ])

nonce-type = bstr .size (8..64)
$$claims-set-claims //= (ueid-label => ueid-type)

ueid-type = bstr .size (7..33)
$$claims-set-claims //= (sueids-label => sueids-type)

sueids-type = {
    + tstr => ueid-type
}
oemid-pen = int

oemid-ieee = bstr .size 3
oemid-random = bstr .size 16

$$claims-set-claims //= (
    oemid-label =>
        oemid-random / oemid-ieee / oemid-pen
)
$$claims-set-claims //=  (
       chip-version-label
    hardware-version-label => hw-version-type hardware-version-type
)

hardware-version-type = [
    version:  tstr,
    scheme:  $version-scheme
]
hardware-model-type = bytes .size (1..32)

$$claims-set-claims //= (
       board-version-label
    hardware-model-label => hw-version-type hardware-model-type
)
$$claims-set-claims //= (
       device-version-label sw-name-label => hw-version-type tstr )

   hw-version-type
$$claims-set-claims //= (sw-version-label => sw-version-type)

sw-version-type = [
    version:  tstr,
    scheme:  $version-scheme ; As defined by CoSWID
]
$$claims-set-claims //= ( sw-name-label => tstr )

   $$claims-set-claims //= (
    security-level-label =>
        security-level-cbor-type /
        security-level-json-type
)

security-level-cbor-type = &(
    unrestricted: 1,
    restricted: 2,
    secure-restricted: 3,
    hardware: 4
)

security-level-json-type =
    "unrestricted" /
    "restricted" /
    "secure-restricted" /
    "hardware"
$$claims-set-claims //= (secure-boot-label => bool)
$$claims-set-claims //=  (
    debug-status-label =>
        debug-status-cbor-type / debug-status-json-type
)

debug-status-cbor-type = &(
    enabled: 0,
    disabled: 1,
    disabled-since-boot: 2,
    disabled-permanently: 3,
    disabled-fully-and-permanently: 4
)

debug-status-json-type =
    "enabled" /
    "disabled" /
    "disabled-since-boot" /
    "disabled-permanently" /
    "disabled-fully-and-permanently"
$$claims-set-claims //= (location-label => location-type)

location-type = {
    latitude => number,
    longitude => number,
    ? altitude => number,
    ? accuracy => number,
    ? altitude-accuracy => number,
    ? heading => number,
    ? speed => number,
    ? timestamp => ~time-int,
    ? age => uint
}

latitude = 1 / "latitude"
longitude = 2 / "longitude"
altitude = 3 / "altitude"
accuracy = 4 / "accuracy"
altitude-accuracy = 5 / "altitude-accuracy"
heading = 6 / "heading"
speed = 7 / "speed"
timestamp = 8 / "timestamp"
age = 9 / "age"
$$claims-set-claims //= (uptime-label => uint)
$$claims-set-claims //=  (boot-seed-label => bytes)
$$claims-set-claims //= (odometer-label => uint)
$$claims-set-claims //= (
    intended-use-label =>
        intended-use-cbor-type / intended-use-json-type
)
intended-use-cbor-type = &(
    generic: 1,
    registration: 2,
    provisioning: 3,
    csr: 4,
    pop: 5
)

intended-use-json-type =
    "generic" /
    "registration" /
    "provisioning" /
    "csr" /
    "pop"
$$claims-set-claims //= (
    dloas-label => [ + dloa-type ]
)

dloa-type = [
    dloa_registrar: ~uri
    dloa_platform_label: text
    ? dloa_application_label: text
]
$$claims-set-claims //= (profile-label => ~uri / ~oid)

   oid = #6.4000(bstr) ; TODO: Replace with CDDL from OID RFC
$$claims-set-claims //= (
    manifests-label => manifests-type
)

manifests-type = [+ $$manifest-formats]

   ; Must be a CoSWID payload type
   ; TODO: signed CoSWIDs

coswid-that-is-a-cbor-tag-xx = tagged-coswid<concise-swid-tag>

$$manifest-formats /= bytes .cbor coswid-that-is-a-cbor-tag-xx
   ; TODO: make this work too
   ;$$manifest-formats /= bytes .cbor SUIT_Envelope_Tagged

   $$claims-set-claims coswid-that-is-a-cbor-tag-xx$$claims-set-claims //= (
    swevidence-label => swevidence-type
)

swevidence-type = [+ $$swevidence-formats]

   ; Must be a CoSWID evidence type that is a CBOR tag
   ; TODO: fix the CDDL so a signed CoSWID is allowed too

coswid-that-is-a-cbor-tag = tagged-coswid<concise-swid-tag>
$$swevidence-formats /= bytes .cbor coswid-that-is-a-cbor-tag
$$claims-set-claims //= (swresults-label => [ + swresult-type ])

verification-result-cbor-type = &(
    verification-not-run: 1,
    verification-indeterminate: 2,
    verification-failed: 3,
    fully-verified: 4,
    partially-verified: 5,

)

verification-result-json-type =
    "verification-not-run" /
    "verification-indeterminate" /
    "verification-failed" /
    "fully-verified" /
    "partially-verified"

verification-objective-cbor-type = &(
    all: 1,
    firmware: 2,
    kernel: 3,
    privileged: 4,
    system-libs: 5,
    partial: 6,
)

verification-objective-json-type =
    "all" /
    "firmware" /
    "kernel" /
    "privileged" /
    "system-libs" /
    "partial"

swresult-type = [
    verification-system: tstr,
    objective: verification-objective-cbor-type /
        verification-objective-json-type,
    result: verification-result-cbor-type /
        verification-result-json-type,
    ? objective-name: tstr
]
   ; This is the part of a token that contains all the submodules.  It
   ; is a peer with the claims in the token, but not a claim, only a
   ; map/object to hold all the submodules.
$$claims-set-claims //= (submods-label => { + text => Submodule })

   ; A submodule can be:
   ; - A simple Claims-Set (encoded in the same format as the token)
   ; - A digest of a detached Claims-Set (encoded in the same format as
   ;    the token)
   ; - A nested token which may be either CBOR or JSON format. Further,
   ;   the mechanism for identifying and containing the nested token
   ;   depends on the format of the surrounding token, particularly
   ;   because JSON doesn't have any equivalent of a CBOR tag so a
   ;   JSON-specific mechanism is invented. Also, there is the issue
   ;   that binary data must be B64 encoded when carried in
   ;   JSON. Nested-Token is defined in the format specific CDDL, not
   ;   here.

   ; Note that at nested token can either be a signed token like a CWT
   ; or JWT, an unsigned token like a UCCS or UJCS, or a DEB (detached
   ; EAT bundle).  The specific encoding of these is format-specific
   ; so it doesn't appear here.

Submodule = Claims-Set / Nested-Token / Detached-Submodule-Digest

   ; This is for both JSON and CBOR.  JSON uses text label for
   ; algorithm from JOSE registry. CBOR uses integer label for
   ; algorithm from COSE registry. In JSON the digest is base64
   ; encoded.

Detached-Submodule-Digest = [
   algorithm : int / text,
   digest : bstr
]
   ; Top-level definition of a DEB for CBOR and JSON
Detached-EAT-Bundle = [
    main-token : Nested-Token,
    detached-claims-sets: {
        + tstr => cbor-wrapped-claims-set / json-wrapped-claims-set

    }
]

   ; text content is a base64url encoded JSON-format Claims-Set

json-wrapped-claims-set = tstr .regexp "[A-Za-z0-9_=-]+"

cbor-wrapped-claims-set = bstr .cbor Claims-Set

8.5.  Collected CDDL for CBOR

; The top-level definition of a CBOR-encoded token.

   CBOR-Token = Tagged-CBOR-Token / Untagged-CBOR-Token

; All forms of a CBOR-encoded token that are a CBOR tag.

   Tagged-CBOR-Token  = CWT-Tagged-Message
   Tagged-CBOR-Token /= UCCS-Tagged-Message
   Tagged-CBOR-Token /= DEB-Tagged-Message

; All forms of a CBOR-encoded token that are not a CBOR tag.

   Untagged-CBOR-Token  = CWT-Untagged-Message
   Untagged-CBOR-Token /= UCCS-Untagged-Message
   Untagged-CBOR-Token /= DEB-Untagged-Message

; The payload of the COSE message is always a Claims-Set

   CWT-Tagged-Message = COSE_Tagged_Message
   CWT-Untagged-Message = COSE_Untagged_Message

   UCCS-Message = UCCS-Tagged-Message / UCCS-Untagged-Message

   UCCS-Tagged-Message = #6.601(UCCS-Untagged-Message)

   UCCS-Untagged-Message = Claims-Set

   DEB-Tagged-Message = #6.602(DEB-Untagged-Message)

   DEB-Untagged-Message = Detached-EAT-Bundle

; This specifies how one fully-formed token is nested inside a
; CBOR-format token.  The fully-formed nested token is any valid
; token, CBOR or JSON (JWT, CWT, UCCS, DEB...)  The mechanism for
; identifying the type of the nested token is specific to the format
; of the surrounding token, CBOR in this case.
;
; A primary reason this is encoding-specific is that JSON does not
; have an equivalent to CBOR tags.
;
; If the data type here is text, then the nested token is JSON
; format, one of a JWT, UJCS or JSON-encoded DEB. The means for
; distinguishing which is in the definition of JSON-encoded
; Nested-Token.  If the data type is bstr, then the nested token
; is CBOR format. It is byte-string wrapped and identified by a
;CBOR tag.

Nested-Token =
    tstr /

   Nested-Token =
       tstr / ; A JSON-encoded Nested-Token (see json-nested-token.cddl)
       bstr .cbor Tagged-CBOR-Token

; This is the CDDL definition of the labels for a CBOR format web
; token, a CWT.  The CDDL for the claims is in web-token-claims.cddl

   iss-label = 1
   sub-label = 2
   aud-label = 3
   exp-label = 4
   nbf-label = 5
   iat-label = 6
   cti-label = 7; The following Claim Keys (labels) are pre-assigned by IANA.
; They are for CBOR-based tokens (CWT and UCCS).
; They are not expected to change in the final publication as an RFC.

nonce-label 7nonce-label = 10
   ueid-label = 11 256
   sueids-label = 257
   oemid-label = 13
security-level-label 258
   hardware-model-label = 14 259
   hardware-version-label = 260
   secure-boot-label = 15 262
   debug-status-label = 16 263
   location-label = 17 264
   profile-label = 18 265
   submods-label = 20

; These are not yet assigned in any way and may change.
; These are intentionally above 24 so as to not use up
; single-byte labels.

sueids-label = <TBD25>
chip-version-label = <TBD26>
board-version-label = <TBD27>
device-version-label = <TBD28>
sw-name-label = <TBD29>
sw-version-label 266
   security-level-label = <TBD30> <TBD>
   uptime-label = <TBD31> <TBD>
   boot-seed-label = <TBD32> <TB>
   odometer-label = <TBD>
   intended-use-label = <TBD33> <TBD>
   dloas-label = <TBD34> <TBD>
   sw-name-label = <TBD>
   sw-version-label = <TBD>
   manifests-label = <TBD35> <TBD>
   swevidence-label = <TBD36> <TBD>
   swresults-label = <TBD37> <TBD>

8.6.  Collected CDDL for JSON

; A JWT message is either a JWS or JWE in compact serialization form
; with the payload a Claims-Set. Compact serialization is the
; protected headers, payload and signature, each b64url encoded and
; separated by a ".". This CDDL simply matches top-level syntax of of
; a JWS or JWE since it is not possible to do more in CDDL.

JWT-Message = text .regexp [A-Za-z0-9_=-]+\.[A-Za-z0-9_=-]+\.[A-Za-z0-9_=-]+

; This defines the JSON equivalent of a UCCS message, a token with
; no integrity or authenticity protection.

UJCS-Message = Claims-Set

; This describes a nested token that occurs inside a JSON-encoded
; token. It uses an array that is made up of a type indicator and the
; actual token.  This is a substitute for the CBOR tag mechanism that
; JSON does not have.

Nested-Token = [
   type : "JWT" / "CBOR" / "UJCS" / "DEB",
   nested-token : JWT-Message /
                  B64URL-Tagged-CBOR-Token /
                  DEB-JSON-Message /
                  UJCS-Message
]

; This text is a Tagged-CBOR-Token (see cbor-token.cddl) that is
; base64url encoded.  For example, it is a CWT that is a COSE_Sign1
; that is a CBOR tag that has been base64url encoded.

B64URL-Tagged-CBOR-Token = tstr .regexp "[A-Za-z0-9_=-]+"
; This is the CDDL definition of the labels for a JSON format web
; token, a JWT.  The CDDL for the claims is in web-token-claims.cddl
iss-label = "iss"
sub-label = "sub"
aud-label = "aud"
exp-label = "exp"
nbf-label = "nbf"
iat-label = "iat"
cti-label = "cti"; The following are claim names for JSON encoded tokens. "cti"nonce-label /= "nonce"

ueid-label /= "ueid"
sueids-label /= "sueids"
nonce-label /= "nonce"
oemid-label /= "oemid"
hardware-model-label /= "hwmodel"
hardware-version-label /= "hwversion"
security-level-label /= "seclevel"
secure-boot-label /= "secboot"
debug-status-label /= "dbgstat"
location-label /= "location"
profile-label /= "eat-profile"
uptime-label /= "uptime"
profile-label
boot-seed-label /= "eat-profile" "bootseed"
odometer-label /= "odometer"
intended-use-label /= "intuse"
boot-seed-label
dloas-label /= "bootseed"
submods-label "dloas"
sw-name-label /= "submods"
timestamp "swname"
sw-version-label /= "timestamp" "swversion"
manifests-label /= "manifests"
swevidence-label /= "swevidence"
dloas-label /= "dloas"
swresults-label /= "swresults"
sw-name-label /= "swname"
sw-version-label
submods-label /= "swversion" "submods"

latitude /= "lat"
longitude /= "long"
altitude /= "alt"
accuracy /= "accry"
altitude-accuracy /= "alt-accry"
heading /= "heading"
speed /= "speed"

9.  IANA Considerations

9.1.  Reuse of CBOR and JSON Web Token (CWT and JWT) Claims Registries

   Claims defined for EAT are compatible with those of CWT and JWT so
   the CWT and JWT Claims Registries, [IANA.CWT.Claims] and
   [IANA.JWT.Claims], are re used.  No new IANA registry is created.

   All EAT claims defined in this document are placed in both
   registries.  All new EAT claims defined subsequently should be placed
   in both registries.

9.2.  Claim Characteristics

   The following is design guidance for creating new EAT claims,
   particularly those to be registered with IANA.

   Much of this guidance is generic and could also be considered when
   designing new CWT or JWT claims.

9.2.1.  Interoperability and Relying Party Orientation

   It is a broad goal that EATs can be processed by Relying Parties in a
   general way regardless of the type, manufacturer or technology of the
   device from which they originate.  It is a goal that there be
   general-purpose verification implementations that can verify tokens
   for large numbers of use cases with special cases and configurations
   for different device types.  This is a goal of interoperability of
   the semantics of claims themselves, not just of the signing, encoding
   and serialization formats.

   This is a lofty goal and difficult to achieve broadly requiring
   careful definition of claims in a technology neutral way.  Sometimes
   it will be difficult to design a claim that can represent the
   semantics of data from very different device types.  However, the
   goal remains even when difficult.

9.2.2.  Operating System and Technology Neutral

   Claims should be defined such that they are not specific to an
   operating system.  They should be applicable to multiple large high-
   level operating systems from different vendors.  They should also be
   applicable to multiple small embedded operating systems from multiple
   vendors and everything in between.

   Claims should not be defined such that they are specific to a SW
   environment or programming language.

   Claims should not be defined such that they are specific to a chip or
   particular hardware.  For example, they should not just be the
   contents of some HW status register as it is unlikely that the same
   HW status register with the same bits exists on a chip of a different
   manufacturer.

   The boot and debug state claims in this document are an example of a
   claim that has been defined in this neutral way.

9.2.3.  Security Level Neutral

   Many use cases will have EATs generated by some of the most secure
   hardware and software that exists.  Secure Elements and smart cards
   are examples of this.  However, EAT is intended for use in low-
   security use cases the same as high-security use case.  For example,
   an app on a mobile device may generate EATs on its own.

   Claims should be defined and registered on the basis of whether they
   are useful and interoperable, not based on security level.  In
   particular, there should be no exclusion of claims because they are
   just used only in low-security environments.

9.2.4.  Reuse of Extant Data Formats

   Where possible, claims should use already standardized data items,
   identifiers and formats.  This takes advantage of the expertise put
   into creating those formats and improves interoperability.

   Often extant claims will not be defined in an encoding or
   serialization format used by EAT.  It is preferred to define a CBOR
   and JSON format for them so that EAT implementations do not require a
   plethora of encoders and decoders for serialization formats.

   In some cases, it may be better to use the encoding and serialization
   as is.  For example, signed X.509 certificates and CRLs can be
   carried as-is in a byte string.  This retains interoperability with
   the extensive infrastructure for creating and processing X.509
   certificates and CRLs.

9.2.5.  Proprietary Claims

   EAT allows the definition and use of proprietary claims.

   For example, a device manufacturer may generate a token with
   proprietary claims intended only for verification by a service
   offered by that device manufacturer.  This is a supported use case.

   In many cases proprietary claims will be the easiest and most obvious
   way to proceed, however for better interoperability, use of general
   standardized claims is preferred.

9.3.  Claims Registered by This Document

   This specification adds the following values to the "JSON Web Token
   Claims" registry established by [RFC7519] and the "CBOR Web Token
   Claims Registry" established by [RFC8392].  Each entry below is an
   addition to both registries (except for the nonce claim which is
   already registered for JWT, but not registered for CWT).

   The "Claim Description", "Change Controller" and "Specification
   Documents" are common and equivalent for the JWT and CWT registries.
   The "Claim Key" and "Claim Value Types(s)" are for the CWT registry
   only.  The "Claim Name" is as defined for the CWT registry, not the
   JWT registry.  The "JWT Claim Name" is equivalent to the "Claim Name"
   in the JWT registry.

9.3.1.  Claims for Early Assignment

   RFC Editor: in the final publication this section should be combined
   with the following section as it will no longer be necessary to
   distinguish claims with early assignment.  Also, the following
   paragraph should be removed.

   The claims in this section have been (requested for / given) early
   assignment according to [RFC7120].  They have been assigned values
   and registered before final publication of this document.  While
   their semantics is not expected to change in final publication, it is
   possible that
   possible that they will.  The JWT Claim Names and CWT Claim Keys are
   not expected to change.

   In draft -06 an early allocation was described.  The processing of
   that early allocation was never correctly completed.  This early
   allocation assigns different numbers for the CBOR claim labels.  This
   early allocation will presumably complete correctly

   o  Claim Name: Nonce

   o  Claim Description: Nonce

   o  JWT Claim Name: "nonce" (already registered for JWT)

   o  Claim Key: TBD (requested value 10)

   o  Claim Value Type(s): byte string

   o  Change Controller: IESG

   o  Specification Document(s): [OpenIDConnectCore], *this document*

   o  Claim Name: UEID

   o  Claim Description: The Universal Entity ID

   o  JWT Claim Name: "ueid"
   o  CWT Claim Key: TBD (requested value 256)

   o  Claim Value Type(s): byte string

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: SUEIDs

   o  Claim Description: Semi-permanent UEIDs

   o  JWT Claim Name: "sueids"

   o  CWT Claim Key: TBD (requested value 257)

   o  Claim Value Type(s): map

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Hardware OEMID

   o  Claim Description: Hardware OEM ID

   o  JWT Claim Name: "oemid"

   o  Claim Key: TBD (requested value 258)

   o  Claim Value Type(s): byte string or integer

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Hardware Model

   o  Claim Description: Model identifier for hardware

   o  JWT Claim Name: "hwmodel"

   o  Claim Key: TBD (requested value 259)

   o  Claim Value Type(s): byte string

   o  Change Controller: IESG
   o  Specification Document(s): *this document*

   o  Claim Name: Hardware Version

   o  Claim Description: Hardware Version Identifier

   o  JWT Claim Name: "hwversion"

   o  Claim Key: TBD (requested value 260)

   o  Claim Value Type(s): array

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Secure Boot

   o  Claim Description: Indicate whether the boot was secure

   o  JWT Claim Name: "secboot"

   o  Claim Key: TBD (requested value 262)

   o  Claim Value Type(s): Boolean

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Debug Status

   o  Claim Description: Indicate status of debug facilities

   o  JWT Claim Name: "dbgstat"

   o  Claim Key: TBD (requested value 263)

   o  Claim Value Type(s): integer or string

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Location

   o  Claim Description: The geographic location
   o  JWT Claim Name: "location"

   o  Claim Key: TBD (requested value 264)

   o  Claim Value Type(s): map

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Profile

   o  Claim Description: Indicates the EAT profile followed

   o  JWT Claim Name: "eat_profile"

   o  Claim Key: TBD (requested value 265)

   o  Claim Value Type(s): URI or OID

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Submodules Section

   o  Claim Description: The section containing submodules

   o  JWT Claim Name: "submods"

   o  Claim Key: TBD (requested value 266)

   o  Claim Value Type(s): map

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

9.3.2.  To be Assigned Claims

   (Early assignment is NOT requested for these claims.  Implementers
   should be aware they will.  The JWT Claim Names and CWT Claim Keys are
   not expected to change. may change)

   o  Claim Name: Nonce Security Level

   o  Claim Description: Nonce Characterization of the security of an Attester
      or submodule

   o  JWT Claim Name: "nonce" (already registered for JWT) "seclevel"

   o  Claim Key: 10 TBD

   o  Claim Value Type(s): byte integer or string

   o  Change Controller: IESG

   o  Specification Document(s): [OpenIDConnectCore], *this document*

   o  Claim Name: UEID Uptime

   o  Claim Description: The Universal Entity ID Uptime

   o  JWT Claim Name: "ueid" "uptime"

   o  CWT  Claim Key: 11 TBD

   o  Claim Value Type(s): byte string unsigned integer

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: OEMID Boot Seed

   o  Claim Description: IEEE-based OEM ID Identifies a boot cycle

   o  JWT Claim Name: "oemid" "bootseed"

   o  Claim Key: 13 TBD

   o  Claim Value Type(s): byte string bytes

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Security Level Intended Use

   o  Claim Description: Characterization Indicates intended use of the security of an Attester
      or submodule EAT

   o  JWT Claim Name: "seclevel" "intuse"

   o  Claim Key: 14 TBD

   o  Claim Value Type(s): integer or string
   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Secure Boot DLOAs

   o  Claim Description: Indicate whether the boot was secure Certifications received as Digital Letters of
      Approval

   o  JWT Claim Name: "secboot" "dloas"

   o  Claim Key: 15 TBD

   o  Claim Value Type(s): Boolean array

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Debug Status SW Name

   o  Claim Description: Indicate status The name of debug facilities the SW running in the entity

   o  JWT Claim Name: "dbgstat" "swname"

   o  Claim Key: 16 TBD

   o  Claim Value Type(s): integer map

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Location SW Version

   o  Claim Description: The geographic location version of SW running in the entity

   o  JWT Claim Name: "location" "swversion"

   o  Claim Key: 17 TBD

   o  Claim Value Type(s): map

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Profile SW Manifests
   o  Claim Description: Indicates Manifests describing the EAT profile followed SW installed on the
      entity

   o  JWT Claim Name: "eat_profile" "manifests"

   o  Claim Key: 18 TBD

   o  Claim Value Type(s): map array

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

   o  Claim Name: Submodules Section SW Evidence

   o  Claim Description: The section containing submodules (not actually
      a claim) Measurements of the SW, memory configuration
      and such on the entity

   o  JWT Claim Name: "submods" "swevidence"

   o  Claim Key: 20 TBD

   o  Claim Value Type(s): map array

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

9.3.2.  To be Assigned Claims

   TODO: add the rest

   o  Claim Name: SW Measurment Results

   o  Claim Description: The results of the claims in here comparing SW measurements to
      reference values

   o  JWT Claim Name: "swresults"

   o  Claim Key: TBD

   o  Claim Value Type(s): array

   o  Change Controller: IESG

   o  Specification Document(s): *this document*

9.3.3.  Version Schemes Registered by this Document

   IANA is requested to register a new value in the "Software Tag
   Version Scheme Values" established by [CoSWID].

   The new value is a version scheme a 13-digit European Article Number
   [EAN-13].  An EAN-13 is also known as an International Article Number
   or most commonly as a bar code.  This version scheme is the ASCII
   text representation of EAN-13 digits, the same ones often printed
   with a bar code.  This version scheme must comply with the EAN
   allocation and assignment rules.  For example, this requires the
   manufacturer to obtain a manufacture code from GS1.

              +-------+---------------------+---------------+
              | Index | Version Scheme Name | Specification |
              +-------+---------------------+---------------+
              | 5     | ean-13              | This document |
              +-------+---------------------+---------------+

9.3.4.  UEID URN Registered by this Document

   IANA is requested to register the following new subtypes in the "DEV
   URN Subtypes" registry under "Device Identification".  See [RFC9039].

   +---------+-----------------------------------------+---------------+
   | Subtype | Description                             | Reference     |
   +---------+-----------------------------------------+---------------+
   | ueid    | Universal Entity Identifier             | This document |
   | sueid   | Semi-permanent Universal Entity         | This document |
   |         | Identifier                              |               |
   +---------+-----------------------------------------+---------------+

9.3.5.  Tag for Detached EAT Bundle

   In the registry [IANA.cbor-tags], IANA is requested to allocate the
   following tag from the FCFS space, with the present document as the
   specification reference.

          +--------+------------+-------------------------------+
          | Tag    | Data Items | Semantics                     |
          +--------+------------+-------------------------------+
          | TBD602 | array      | Detached EAT Bundle Section 5 |
          +--------+------------+-------------------------------+

10.  Privacy Considerations

   Certain EAT claims can be used to track the owner of an entity and
   therefore, implementations should consider providing privacy-
   preserving options dependent on the intended usage of the EAT.
   Examples would include suppression of location claims for EAT's
   provided to unauthenticated consumers.

10.1.  UEID and SUEID Privacy Considerations

   A UEID is usually not privacy-preserving.  Any set of Relying Parties
   that receives tokens that happen to be from a single device particular entity will
   be able to know the tokens are all from the same device entity and be able
   to track the device. it.

   Thus, in many usage situations UEID violates governmental privacy
   regulation.  In other usage situations a UEID will not be allowed for
   certain products like browsers that give privacy for the end user.
   It will often be the case that tokens will not have a UEID for these
   reasons.

   An SUEID is also usually not privacy-preserving.  In some cases it
   may have fewer privacy issues than a UEID depending on when and how
   and when it is generated.

   There are several strategies that can be used to still be able to put
   UEIDs and SUEIDs in tokens:

   o  The device entity obtains explicit permission from the user of the device entity
      to use the UEID/SUEID.  This may be through a prompt.  It may also
      be through a license agreement.  For example, agreements for some
      online banking and brokerage services might already cover use of a
      UEID/SUEID.

   o  The UEID/SUEID is used only in a particular context or particular
      use case.  It is used only by one Relying Party.

   o  The device entity authenticates the Relying Party and generates a derived
      UEID/SUEID just for that particular Relying Party.  For example,
      the Relying Party could prove their identity cryptographically to
      the device, entity, then the device entity generates a UEID just for that Relying
      Party by hashing a proofed Relying Party ID with the main device entity
      UEID/SUEID.

   Note that some of these privacy preservation strategies result in
   multiple UEIDs and SUEIDs per device. entity.  Each UEID/SUEID is used in a
   different context, use case or system on the device. entity.  However, from
   the view of the Relying Party, there is just one UEID and it is still
   globally universal across manufacturers.

10.2.  Location Privacy Considerations

   Geographic location is most always considered personally identifiable
   information.  Implementers should consider laws and regulations
   governing the transmission of location data from end user devices to
   servers and services.  Implementers should consider using location
   management facilities offered by the operating system on the device entity
   generating the attestation.  For example, many mobile phones prompt
   the user for permission when before sending location data.

10.3.  Replay Protection and Privacy

   EAT offers 2 primary mechanisms for token replay protection (also
   sometimes known as token "freshness"): the cti/jti claim and the
   nonce claim.  The cti/jti claim in a CWT/JWT is a field that may be
   optionally included in the EAT and is in general derived on the same
   device in which the entity is instantiated.  The nonce claim is based
   on a value that is usually derived remotely (outside of the entity).
   These claims can be used to extract and convey personally-identifying
   information either inadvertently or by intention.  For instance, an
   implementor may choose a cti that is equivalent to a username
   associated with the device (e.g., account login).  If the token is
   inspected by a 3rd-party then this information could be used to
   identify the source of the token or an account associated with the
   token (e.g., if the account name is used to derive the nonce).  In
   order to avoid the conveyance of privacy-related information in
   either the cti/jti or nonce claims, these fields should be derived
   using a salt that originates from a true and reliable random number
   generator or any other source of randomness that would still meet the
   target system requirements for replay protection.

11.  Security Considerations

   The security considerations provided in Section 8 of [RFC8392] and
   Section 11 of [RFC7519] apply to EAT in its CWT and JWT form,
   respectively.  In addition, implementors should consider the
   following.

11.1.  Key Provisioning

   Private key material can be used to sign and/or encrypt the EAT, or
   can be used to derive the keys used for signing and/or encryption.
   In some instances, the manufacturer of the entity may create the key
   material separately and provision the key material in the entity
   itself.  The manfuacturer of any entity that is capable of producing
   an EAT should take care to ensure that any private key material be
   suitably protected prior to provisioning the key material in the
   entity itself.  This can require creation of key material in an
   enclave (see [RFC4949] for definition of "enclave"), secure
   transmission of the key material from the enclave to the entity using
   an appropriate protocol, and persistence of the private key material
   in some form of secure storage to which (preferably) only the entity
   has access.

11.1.1.  Transmission of Key Material

   Regarding transmission of key material from the enclave to the
   entity, the key material may pass through one or more intermediaries.
   Therefore some form of protection ("key wrapping") may be necessary.
   The transmission itself may be performed electronically, but can also
   be done by human courier.  In the latter case, there should be
   minimal to no exposure of the key material to the human (e.g.
   encrypted portable memory).  Moreover, the human should transport the
   key material directly from the secure enclave where it was created to
   a destination secure enclave where it can be provisioned.

11.2.  Transport Security

   As stated in Section 8 of [RFC8392], "The security of the CWT relies
   upon on the protections offered by COSE".  Similar considerations
   apply to EAT when sent as a CWT.  However, EAT introduces the concept
   of a nonce to protect against replay.  Since an EAT may be created by
   an entity that may not support the same type of transport security as
   the consumer of the EAT, intermediaries may be required to bridge
   communications between the entity and consumer.  As a result, it is
   RECOMMENDED that both the consumer create a nonce, and the entity
   leverage the nonce along with COSE mechanisms for encryption and/or
   signing to create the EAT.

   Similar considerations apply to the use of EAT as a JWT.  Although
   the security of a JWT leverages the JSON Web Encryption (JWE) and
   JSON Web Signature (JWS) specifications, it is still recommended to
   make use of the EAT nonce.

11.3.  Multiple EAT Consumers

   In many cases, more than one EAT consumer may be required to fully
   verify the entity attestation.  Examples include individual consumers
   for nested EATs, or consumers for individual claims with an EAT.
   When multiple consumers are required for verification of an EAT, it
   is important to minimize information exposure to each consumer.  In
   addition, the communication between multiple consumers should be
   secure.

   For instance, consider the example of an encrypted and signed EAT
   with multiple claims.  A consumer may receive the EAT (denoted as the
   "receiving consumer"), decrypt its payload, verify its signature, but
   then pass specific subsets of claims to other consumers for
   evaluation ("downstream consumers").  Since any COSE encryption will
   be removed by the receiving consumer, the communication of claim
   subsets to any downstream consumer should leverage a secure protocol
   (e.g.one that uses transport-layer security, i.e. TLS),
   However, assume the EAT of the previous example is hierarchical and
   each claim subset for a downstream consumer is created in the form of
   a nested EAT.  Then transport security between the receiving and
   downstream consumers is not strictly required.  Nevertheless,
   downstream consumers of a nested EAT should provide a nonce unique to
   the EAT they are consuming.

12.  References

12.1.  Normative References

   [CBOR.OID]
              Bormann, C., "Concise Binary Object Representation (CBOR)
              Tags for Object Identifiers", draft-ietf-cbor-tags-oid-08
              (work in progress), May 2021.

   [CoSWID]   Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
              Waltermire, "Concise Software Identification Tags", draft-
              ietf-sacm-coswid-19
              ietf-sacm-coswid-20 (work in progress), October 2021. January 2022.

   [DLOA]     "Digital Letter of Approval", November 2015,
              <https://globalplatform.org/wp-content/uploads/2015/12/
              GPC_DigitalLetterOfApproval_v1.0.pdf>.

   [EAN-13]   GS1, "International Article Number - EAN/UPC barcodes",
              2019, <https://www.gs1.org/standards/barcodes/ean-upc>.

   [FIDO.AROE]
              The FIDO Alliance, "FIDO Authenticator Allowed Restricted
              Operating Environments List", November 2020,
              <https://fidoalliance.org/specs/fido-security-
              requirements/fido-authenticator-allowed-restricted-
              operating-environments-list-v1.2-fd-20201102.html>.

   [IANA.cbor-tags]
              "IANA CBOR Tags Registry", n.d.,
              <https://www.iana.org/assignments/cbor-tags/cbor-
              tags.xhtml>.

   [IANA.CWT.Claims]
              IANA, "CBOR Web Token (CWT) Claims",
              <http://www.iana.org/assignments/cwt>.

   [IANA.JWT.Claims]
              IANA, "JSON Web Token (JWT) Claims",
              <https://www.iana.org/assignments/jwt>.

   [OpenIDConnectCore]
              Sakimura, N., Bradley, J., Jones, M., Medeiros, B. D., and
              C. Mortimore, "OpenID Connect Core 1.0 incorporating
              errata set 1", November 2014,
              <https://openid.net/specs/openid-connect-core-1_0.html>.

   [PEN]      "Private Enterprise Number (PEN) Request", n.d.,
              <https://pen.iana.org/pen/PenApplication.page>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3986]  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/info/rfc3986>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/info/rfc7159>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/info/rfc7515>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <https://www.rfc-editor.org/info/rfc7516>.

   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,
              <https://www.rfc-editor.org/info/rfc7517>.

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

   [RFC7800]  Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
              Possession Key Semantics for JSON Web Tokens (JWTs)",
              RFC 7800, DOI 10.17487/RFC7800, April 2016,
              <https://www.rfc-editor.org/info/rfc7800>.

   [RFC8126]  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,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8152]  Schaad, J., "CBOR Object Signing and Encryption (COSE)",
              RFC 8152, DOI 10.17487/RFC8152, July 2017,
              <https://www.rfc-editor.org/info/rfc8152>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8392]  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/info/rfc8392>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/info/rfc8610>.

   [RFC8747]  Jones, M., Seitz, L., Selander, G., Erdtman, S., and H.
              Tschofenig, "Proof-of-Possession Key Semantics for CBOR
              Web Tokens (CWTs)", RFC 8747, DOI 10.17487/RFC8747, March
              2020, <https://www.rfc-editor.org/info/rfc8747>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949, 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

   [RFC9090]  Bormann, C., "Concise Binary Object Representation (CBOR)
              Tags for Object Identifiers", RFC 9090,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>. 10.17487/RFC9090, July 2021,
              <https://www.rfc-editor.org/info/rfc9090>.

   [ThreeGPP.IMEI]
              3GPP, "3rd Generation Partnership Project; Technical
              Specification Group Core Network and Terminals; Numbering,
              addressing and identification", 2019,
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=729>.

   [UCCS.Draft]
              Birkholz, H., O'Donoghue, J., Cam-Winget, N., and C.
              Bormann, "A CBOR Tag for Unprotected CWT Claims Sets",
              draft-ietf-rats-uccs-01
              draft-ietf-rats-uccs-02 (work in progress), July 2021. January 2022.

   [WGS84]    National Geospatial-Intelligence Agency (NGA), "WORLD
              GEODETIC SYSTEM 1984, NGA.STND.0036_1.0.0_WGS84", July
              2014, <https://earth-info.nga.mil/php/
              download.php?file=coord-wgs84>.

12.2.  Informative References

   [BirthdayAttack]
              "Birthday attack",
              <https://en.wikipedia.org/wiki/Birthday_attack.>.

   [CBOR.Cert.Draft]
              Mattsson, J. P., Selander, G., Raza, S., Hoeglund, J., and
              M. Furuhed, "CBOR Encoded X.509 Certificates (C509
              Certificates)", draft-ietf-cose-cbor-encoded-cert-02 draft-ietf-cose-cbor-encoded-cert-03 (work
              in progress), July 2021. January 2022.

   [Common.Criteria]
              "Common Criteria for Information Technology Security
              Evaluation", April 2017,
              <https://www.commoncriteriaportal.org/cc/>.

   [COSE.X509.Draft]
              Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Header parameters for carrying and referencing X.509
              certificates", draft-ietf-cose-x509-08 (work in progress),
              December 2020.

   [ECMAScript]
              "Ecma International, "ECMAScript Language Specification,
              5.1 Edition", ECMA Standard 262", June 2011,
              <http://www.ecma-international.org/ecma-262/5.1/ECMA-
              262.pdf>.

   [FIPS-140]
              National Institue of Standards, "Security Requirements for
              Cryptographic Modules", May 2001,
              <https://csrc.nist.gov/publications/detail/fips/140/2/
              final>.

   [IEEE.802-2001]
              "IEEE Standard For Local And Metropolitan Area Networks
              Overview And Architecture", 2007,
              <https://webstore.ansi.org/standards/ieee/
              ieee8022001r2007>.

   [IEEE.802.1AR]
              "IEEE Standard, "IEEE 802.1AR Secure Device Identifier"",
              December 2009, <http://standards.ieee.org/findstds/
              standard/802.1AR-2009.html>.

   [IEEE.RA]  "IEEE Registration Authority",
              <https://standards.ieee.org/products-services/regauth/
              index.html>.

   [OUI.Guide]
              "Guidelines for Use of Extended Unique Identifier (EUI),
              Organizationally Unique Identifier (OUI), and Company ID
              (CID)", August 2017,
              <https://standards.ieee.org/content/dam/ieee-
              standards/standards/web/documents/tutorials/eui.pdf>.

   [OUI.Lookup]
              "IEEE Registration Authority Assignments",
              <https://regauth.standards.ieee.org/standards-ra-web/pub/
              view.html#registries>.

   [RATS.Architecture]
              Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote Attestation Procedures Architecture",
              draft-ietf-rats-architecture-12
              draft-ietf-rats-architecture-15 (work in progress), April
              2021.
              February 2022.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <https://www.rfc-editor.org/info/rfc4122>.

   [RFC4422]  Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple
              Authentication and Security Layer (SASL)", RFC 4422,
              DOI 10.17487/RFC4422, June 2006,
              <https://www.rfc-editor.org/info/rfc4422>.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <https://www.rfc-editor.org/info/rfc4949>.

   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code
              Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
              2014, <https://www.rfc-editor.org/info/rfc7120>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9039]  Arkko, J., Jennings, C., and Z. Shelby, "Uniform Resource
              Names for Device Identifiers", RFC 9039,
              DOI 10.17487/RFC9039, June 2021,
              <https://www.rfc-editor.org/info/rfc9039>.

   [W3C.GeoLoc]
              Worldwide Web Consortium, "Geolocation API Specification
              2nd Edition", January 2018, <https://www.w3.org/TR/
              geolocation-API/#coordinates_interface>.

Appendix A.  Examples

   These examples are either UCCS, shown as CBOR diagnostic, or UJCS
   messages.  Full CWT and JWT examples with signing and encryption are
   not given.

   All UCCS examples can be the payload of a CWT.  To do so, they must
   be converted from the UCCS message to a Claims-Set, which is achieve
   by "removing" the tag.

   UJCS messages can be directly used as the payload of a JWT.

   WARNING: These examples use tag and label numbers not yet assigned by
   IANA.

A.1.  Simple TEE Attestation label numbers not yet assigned by
   IANA.

A.1.  Simple TEE Attestation

   This is a simple attestation of a TEE that includes a manifest that
   is a payload CoSWID to describe the TEE's software.

   / This is a UCCS EAT that describes a simple TEE. /

   601({
       / nonce /           10: h'948f8860d13a463e',
       / security-level / 261: 3, / secure-restricted /
       / secure-boot /    262: true,
       / debug-status /   263: 2, / disabled-since-boot /
       / manfests /       273: [
                                  / This is byte-string wrapped      /
                                  / payload CoSWID. It gives the TEE /
                                  / software name, the version and   /
                                  / the  name of the file it is in.  /
                                  h' da53574944a60064336132340c01016b
                                     41636d6520544545204f530d65332e31
                                     2e340282a2181f6b41636d6520544545
                                     204f53182101a2181f6b41636d652054
                                     4545204f5318210206a111a118186e61
                                     636d655f7465655f332e657865'
                           ]
   })
   / A payload CoSWID created by the SW vendor. All this really does /
   / is name the TEE SW, its version and lists the one file that     /
   / makes up the TEE. /

   1398229316({
       / Unique CoSWID ID /    0: "3a24",
       / tag-version /        12: 1,
       / software-name /       1: "Acme TEE OS",
       / software-version /   13: "3.1.4",
       / entity /              2: [
                                      {
           / entity-name /                31: "Acme TEE OS",
           / role        /                33: 1 / tag-creator /
                                      },
                                      {
           / entity-name /                31: "Acme TEE OS",
           / role        /                33: 2 / software-creator /
                                      }
                                  ],
       / payload /                6: {
           / ...file /                17: {
               / ...fs-name /             24: "acme_tee_3.exe"
                                      }
                                  }
   })

A.2.  Submodules for Board and Device
/ This is a simple attestation example shows use of a TEE that includes a manifest that
   is a payload CoSWID submodules to describe give information  /
/ about the TEE's software. chip, board and overall device.                 / This is a UCCS EAT that describes a simple TEE.
/

   601({                                                           / nonce
/           10: h'948f8860d13a463e', The main attestation is associated with the chip with the / security-level
/  14: 3, CPU and running the main OS. It is what has the keys and  / secure-restricted
/ produces the token.                                       / secure-boot
/     15: true,                                                           / debug-status
/    16: 2, The board is made by a different vendor than the chip.    / disabled-since-boot
/ Perhaps it is some generic IoT board.                     /
/ manfests                                                           /        35: [
/ This The device is byte-string wrapped some specific appliance that is made by a   /
/ payload CoSWID. It gives different vendor than either the TEE chip or the board.       /
/ software name, the version and                                                           /
/ Here the  name of board and device submodules aren't the file it is in. typical   /
                                  h' da53574944a60064336132340c01016b
                                     41636d6520544545204f530d65332e31
                                     2e340282a2181f6b41636d6520544545
                                     204f53182101a2181f6b41636d652054
                                     4545204f5318210206a111a118186e61
                                     636d655f7465655f332e657865'
                           ]
   })
/ A payload CoSWID created target environments as described by the SW vendor. All this really does RATS architecture /
/ is document, but they are a valid use of submodules.         /

{
    / nonce /           10: h'948f8860d13a463e8e',
    / UEID /           256: h'0198f50a4ff6c05861c8860d13a638ea',
    / HW OEM ID /      258: h'894823', / IEEE OUI format OEM ID /
    / HW Model ID /    259: h'549dcecc8b987c737b44e40f7c635ce8'
                              / Hash of chip model name the TEE SW, its /,
    / HW Version /     260: ["1.3.4", 1], / Multipartnumeric version and lists the one file that /
    / makes up the TEE. SW Name /        271: "Acme OS",
    / SW Version /     272: ["3.5.5", 1],
    / secure-boot /    262: true,
    / debug-status /   263: 3, /

   1398229316({ permanent-disable  / Unique CoSWID ID
    /    0: "3a24", timestamp (iat) / tag-version  6: 1526542894,
    /        12: 1, security-level / software-name 261: 3, /       1: "Acme TEE OS", secure restricted OS / software-version
    /   13: "3.1.4", submods / entity 266: {
        /              2: [ A submodule to hold some claims about the circuit board /
        "board" :  {
            / entity-name HW OEM ID /                31: "Acme TEE OS",   258: h'9bef8787eba13e2c8f6e7cb4b1f4619a',
            / role HW Model ID /                33: 1 259: h'ee80f5a66c1fb9742999a8fdab930893'
                                      / tag-creator Hash of board module name /,
            /
                                      },
                                      { HW Version / entity-name  260: ["2.0a", 2] /                31: "Acme TEE OS", multipartnumeric+suffix / role
        },

        /                33: 2 A submodule to hold claims about the overall device / software-creator
        "device" :  {
            /
                                      }
                                  ], HW OEM ID / payload   258: 61234, /                6: { PEN Format OEM ID / ...file
            /                17: { HW Version / ...fs-name  260: ["4012345123456", 5] / EAN-13 format (barcode) /             24: "acme_tee_3.exe"
        }
    }
   })

A.2.
}
A.3.  EAT Produced by Attestation Hardware Block

   / This is an example of a token produced by a HW block            /
   / purpose-built for attestation.  Only the nonce claim changes    /
   / from one attestation to the next as the rest  either come       /
   / directly from the hardware or from one-time-programmable memory /
   / (e.g. a fuse). 47 bytes encoded in CBOR (8 byte nonce, 16 byte  /
   / UEID). /

   601({
       / nonce /           10: h'948f8860d13a463e',
       / UEID /            11:           256: h'0198f50a4ff6c05861c8860d13a638ea',
       / OEMID /           13:          258: 64242, / Private Enterprise Number /
       / security-level /  14: 261: 4, / hardware level security /
       / secure-boot /     15:    262: true,
       / debug-status /    16:   263: 3, / disabled-permanently /
       / chip-version HW version /    26:     260: [ "3.1", 1 ] / Type is multipartnumeric /
   })

A.3.

A.4.  Detached EAT Bundle

   In this DEB main token is produced by a HW attestation block.  The
   detached Claims-Set is produced by a TEE and is largely identical to
   the Simple TEE examples above.  The TEE digests its Claims-Set and
   feeds that digest to the HW block.

   In a better example the attestation produced by the HW block would be
   a CWT and thus signed and secured by the HW block.  Since the
   signature covers the digest from the TEE that Claims-Set is also
   secured.

   The DEB itself can be assembled by untrusted SW.

   / This is a detached EAT bundle (DEB) tag.  /

   602([

       / First part is a full EAT token with claims like nonce and /
       / UEID. Most importantly, it includes a submodule that is a /
       / detached digest which is the hash of the "TEE" claims set /
       / in the next section.                                      /
       /                                                           /
       / This token here is in UCCS format (unsigned). In a more   /
       / realistic example, it would be a signed CWT.              /
       h'd90259a80a48948f8860d13a463e0b500198f50a4ff6c058
         61c8860d13a638ea0d19faf20e040ff51003181a8263332e
         310114a163544545822f5820e5cf95fd24fab71446742dd5
         8d43dae178e55fe2b94291a9291082ffc2635a0b',
       h'd90259a80a48948f8860d13a463e190100500198
       f50a4ff6c05861c8860d13a638ea19010219faf2
       19010504190106f5190107031901048263332e31
       0119010aa163544545822f5820e5cf95fd24fab7
       1446742dd58d43dae178e55fe2b94291a9291082
       ffc2635a0b',
       {
          / A CBOR-encoded byte-string wrapped EAT claims-set. It /
          / contains claims suitable for a TEE                    /
          "TEE" : h'a50a48948f8860d13a463e0e030ff51002182381
                    585dda53574944a60064336132340c01016b4163
                    6d6520544545204f530d65332e312e340282a218
                    1f6b41636d6520544545204f53182101a2181f6b
                    41636d6520544545204f5318210206a111a11818
                    6e61636d655f7465655f332e657865' h'a50a48948f8860d13a463e19010503190106f519
                    01070219011181585dda53574944a60064336132
                    340c01016b41636d6520544545204f530d65332e
                    312e340282a2181f6b41636d6520544545204f53
                    182101a2181f6b41636d6520544545204f531821
                    0206a111a118186e61636d655f7465655f332e65
                    7865'
       }
    ])

   / This example contains submodule that is a detached digest,   /
   / which is the hash of a Claims-Set convey outside this token. /
   / Other than that is is the other example of a token from an   /
   / attestation HW block                                         /

   601({
       / nonce /           10: h'948f8860d13a463e',
       / UEID /            11:           256: h'0198f50a4ff6c05861c8860d13a638ea',
       / OEMID /           13:          258: 64242, / Private Enterprise Number /
       / security-level /  14: 261: 4, / hardware level security /
       / secure-boot /     15:    262: true,
       / debug-status /    16:   263: 3, / disabled-permanently /
       / chip-version hw version /    26:     260: [ "3.1", 1 ], / multipartnumeric /
       / submods/          20:         266: {
                                   "TEE": [ / detached digest submod /
                                       -16, / SHA-256 /
                                       h'e5cf95fd24fab7144674
                                         2dd58d43dae178e55fe2
                                         b94291a9291082ffc2635
                                         a0b'
                                   ]
                               }
   })

A.4.

A.5.  Key / Key Store Attestation

   / This is an attestation of a public key and the key store     /
   / implementation that protects and manages it. The key store   /
   / implementation is in a security-oriented execution           /
   / environment separate from the high-level OS, for example a   /
   / TEE. The key store is the Attester.                          /
   /                                                              /
   / There is some attestation of the high-level OS, just version /
   / and boot & debug status. It is a Claims-Set submodule because/
   / it has lower security level than the key store. The key      /
   / store's implementation has access to info about the HLOS, so /
   / it is able to include it.                                    /
   /                                                              /
   / A key and an indication of the user authentication given to  /
   / allow access to the key is given. The labels for these are   /
   / in the private space since this is just a hypothetical       /
   / example, not part of a standard protocol.                    /
   /                                                              /
   / This is similar to Android Key Attestation.                  /

   601({
       / nonce /           10: h'948f8860d13a463e',
       / security-level /  14: 261: 3, / secure-restricted /
       / secure-boot /    262: true,
       / debug-status /    16:   263: 2, / disabled-since-boot /
       / secure-boot /     15: true,
       / manifests /       35:      273: [
                                   h'da53574944a600683762623334383766
                                     0c000169436172626f6e6974650d6331
                                     2e320e0102a2181f75496e6475737472
                                     69616c204175746f6d6174696f6e1821
                                     02'
                                    / Above is an encoded CoSWID     /
                                    / with the following data        /
                                    /   SW Name: "Carbonite"         /
                                    /   SW Vers: "1.2"               /
                                    /   SW Creator:                  /
                                    /      "Industrial Automation"   /
                               ],
       / expiration /       4: 1634324274, / 2021-10-15T18:57:54Z /
       / creation time /    6: 1634317080, / 2021-10-15T16:58:00Z /
                      -80000 : "fingerprint",
                      -80001 : { / The key -- A COSE_Key  /
                   / kty /       1: 2, / EC2, eliptic curve with x & y /
                   / kid /       2: h'36675c206f96236c3f51f54637b94ced',
                   / curve /    -1: 2, / curve is P-256 /
                   / x-coord /  -2: h'65eda5a12577c2bae829437fe338701a
                                      10aaa375e1bb5b5de108de439c08551d',
                   / y-coord /  -3: h'1e52ed75701163f7f9e40ddf9f341b3d
                                      c9ba860af7e0ca7ca7e9eecd0084d19c'
                },

       / submods /        20        266 : {
                              "HLOS" : { / submod for high-level OS /
            / nonce /             10: h'948f8860d13a463e',
              / security-level /  14: 261: 1, / unrestricted /
              / secure-boot /     15:    262: true,
              / manifests /       35:      273: [
                                       h'da53574944a600687337
                                         6537346b78380c000168
                                         44726f6964204f530d65
                                         52322e44320e0302a218
                                         1F75496E647573747269
                                         616c204175746f6d6174
                                         696f6e182102'
                                        / Above is an encoded CoSWID /
                                        / with the following data:   /
                                        /   SW Name: "Droid OS"      /
                                        /   SW Vers: "R2.D2"         /
                                        /   SW Creator:              /
                                        /     "Industrial Automation"/
                                  ]
                              }
                          }
   })

A.5.

A.6.  SW Measurements of an IoT Device

   This is a simple token that might be for and IoT device.  It includes
   CoSWID format measurments of the SW.  The CoSWID is in byte-string
   wrapped in the token and also shown in diagnostic form.

   / This EAT UCCS is for an IoT device with a TEE. The attestation   /
   / is produced by the TEE. There is a submodule for the IoT OS (the /
   / main OS of the IoT device that is not as secure as the TEE). The /
   / submodule contains claims for the IoT OS. The TEE also measures  /
   / the IoT OS and puts the measurements in the submodule.           /

   601({
       / nonce /           10: h'948f8860d13a463e',
       / security-level /  14: 261: 3, / secure-restricted /
       / secure-boot /     15:    262: true,
       / debug-status /    16:   263: 2, / disabled-since-boot /
       / OEMID /           13:          258: h'8945ad', / IEEE CID based /
       / UEID /            11:           256: h'0198f50a4ff6c05861c8860d13a638ea',
       / sumods /          20:         266: {
                               "OS" : {
           / security-level /      14:     261: 2, / restricted /
           / secure-boot /         15:        262: true,
           / debug-status /        16:       263: 2, / disabled-since-boot /
           / swevidence /          36:         274: [
                                       / This is a byte-string wrapped /
                                       / evidence CoSWID. It has       /
                                       / hashes of the main files of   /
                                       / the IoT OS.  /
                                       h'da53574944a600663463613234350c
                                         17016d41636d6520522d496f542d4f
                                         530d65332e312e3402a2181f724163
                                         6d6520426173652041747465737465
                                         7218210103a11183a318187161636d
                                         655f725f696f745f6f732e65786514
                                         1a0044b349078201582005f6b327c1
                                         73b4192bd2c3ec248a292215eab456
                                         611bf7a783e25c1782479905a31818
                                         6d7265736f75726365732e72736314
                                         1a000c38b10782015820c142b9aba4
                                         280c4bb8c75f716a43c99526694caa
                                         be529571f5569bb7dc542f98a31818
                                         6a636f6d6d6f6e2e6c6962141a0023
                                         3d3b0782015820a6a9dcdfb3884da5
                                         f884e4e1e8e8629958c2dbc7027414
                                         43a913e34de9333be6'
                                   ]
                               }
                           }
   })

   / An evidence CoSWID created for the "Acme R-IoT-OS" created by /
   / the "Acme Base Attester" (both fictious names).  It provides  /
   / measurements of the SW (other than the attester SW) on the    /
   / device. /

   1398229316({
       / Unique CoSWID ID /    0: "4ca245",
       / tag-version /        12: 23, / Attester-maintained counter /
       / software-name /       1: "Acme R-IoT-OS",
       / software-version /   13: "3.1.4",
       / entity /              2: {
           / entity-name /        31: "Acme Base Attester",
           / role        /        33: 1 / tag-creator /
                               },
       / evidence /            3: {
           / ...file /             17: [
                                       {
               / ...fs-name /              24: "acme_r_iot_os.exe",
               / ...size    /              20: 4502345,
               / ...hash    /               7: [
                                                1, / SHA-256 /
                                                h'05f6b327c173b419
                                                  2bd2c3ec248a2922
                                                  15eab456611bf7a7
                                                  83e25c1782479905'
                                            ]
                                       },
                                       {
               / ...fs-name /              24: "resources.rsc",
               / ...size    /              20: 800945,
               / ...hash    /               7: [
                                                 1, / SHA-256 /
                                                h'c142b9aba4280c4b
                                                  b8c75f716a43c995
                                                  26694caabe529571
                                                  f5569bb7dc542f98'
                                            ]
                                       },
                                       {
               / ...fs-name /              24: "common.lib",
               / ...size    /              20: 2309435,
               / ...hash    /               7: [
                                                1, / SHA-256 /
                                                h'a6a9dcdfb3884da5
                                                  f884e4e1e8e86299
                                                  58c2dbc702741443
                                                  a913e34de9333be6'
                                            ]
                                       }
                                   ]

                               }
   })

A.6.

A.7.  Attestation Results in JSON format

   This is a UJCS format token that might be the output of a Verifier
   that evaluated the IoT Attestation example immediately above.

   This particular Verifier knows enough about the TEE Attester to be
   able to pass claims like security level directly through to the
   Relying Party.  The Verifier also knows the Reference Values for the
   measured SW components and is able to check them.  It informs the
   Relying Party that they were correct in the swresults claim.
   "Trustus Verifications" is the name of the services that verifies the
   SW component measurements.

   This UJCS is identical to JSON-encoded Claims-Set that could be a JWT
   payload.

   {
       "nonce" : "lI+IYNE6Rj4=",
       "seclevel" : "secure-restricted",
       "secboot" : true,
       "dbgstat" : "disabled-since-boot",
       "OEMID" : "iUWt",
       "UEID" : "AZj1Ck/2wFhhyIYNE6Y4",
       "submods" : {
           "seclevel" : "restricted",
           "secboot" : true,
           "dbgstat" : "disabled-since-boot",
           "swname" : "Acme R-IoT-OS",
           "sw-version" : [
               "3.1.4"
           ],
           "swresults" : [
               [
                   "Trustus Verifications",
                   "all",
                   "fully-verified"
               ]
          ]
   }

Appendix B.  UEID Design Rationale

B.1.  Collision Probability

   This calculation is to determine the probability of a collision of
   UEIDs given the total possible entity population and the number of
   entities in a particular entity management database.

   Three different sized databases are considered.  The number of
   devices per person roughly models non-personal devices such as
   traffic lights, devices in stores they shop in, facilities they work
   in and so on, even considering individual light bulbs.  A device may
   have individually attested subsystems, for example parts of a car or
   a mobile phone.  It is assumed that the largest database will have at
   most 10% of the world's population of devices.  Note that databases
   that handle more than a trillion records exist today.

   The trillion-record database size models an easy-to-imagine reality
   over the next decades.  The quadrillion-record database is roughly at
   the limit of what is imaginable and should probably be accommodated.
   The 100 quadrillion datadbase is highly speculative perhaps involving
   nanorobots for every person, livestock animal and domesticated bird.
   It is included to round out the analysis.

   Note that the items counted here certainly do not have IP address and
   are not individually connected to the network.  They may be connected
   to internal buses, via serial links, Bluetooth and so on.  This is
   not the same problem as sizing IP addresses.

   +---------+------------+--------------+------------+----------------+
   | People  | Devices /  | Subsystems / | Database   | Database Size  |
   |         | Person     | Device       | Portion    |                |
   +---------+------------+--------------+------------+----------------+
   | 10      | 100        | 10           | 10%        | trillion       |
   | billion |            |              |            | (10^12)        |
   | 10      | 100,000    | 10           | 10%        | quadrillion    |
   | billion |            |              |            | (10^15)        |
   | 100     | 1,000,000  | 10           | 10%        | 100            |
   | billion |            |              |            | quadrillion    |
   |         |            |              |            | (10^17)        |
   +---------+------------+--------------+------------+----------------+

   This is conceptually similar to the Birthday Problem where m is the
   number of possible birthdays, always 365, and k is the number of
   people.  It is also conceptually similar to the Birthday Attack where
   collisions of the output of hash functions are considered.

   The proper formula for the collision calculation is
      p = 1 - e^{-k^2/(2n)}

      p   Collision Probability
      n   Total possible population
      k   Actual population

   However, for the very large values involved here, this formula
   requires floating point precision higher than commonly available in
   calculators and SW so this simple approximation is used.  See
   [BirthdayAttack].

      p = k^2 / 2n

   For this calculation:

      p  Collision Probability
      n  Total population based on number of bits in UEID
      k  Population in a database

   +----------------------+--------------+--------------+--------------+
   | Database Size        | 128-bit UEID | 192-bit UEID | 256-bit UEID |
   +----------------------+--------------+--------------+--------------+
   | trillion (10^12)     | 2 * 10^-15   | 8 * 10^-35   | 5 * 10^-55   |
   | quadrillion (10^15)  | 2 * 10^-09   | 8 * 10^-29   | 5 * 10^-49   |
   | 100 quadrillion      | 2 * 10^-05   | 8 * 10^-25   | 5 * 10^-45   |
   | (10^17)              |              |              |              |
   +----------------------+--------------+--------------+--------------+

   Next, to calculate the probability of a collision occurring in one
   year's operation of a database, it is assumed that the database size
   is in a steady state and that 10% of the database changes per year.
   For example, a trillion record database would have 100 billion states
   per year.  Each of those states has the above calculated probability
   of a collision.

   This assumption is a worst-case since it assumes that each state of
   the database is completely independent from the previous state.  In
   reality this is unlikely as state changes will be the addition or
   deletion of a few records.

   The following tables gives the time interval until there is a
   probability of a collision based on there being one tenth the number
   of states per year as the number of records in the database.

     t = 1 / ((k / 10) * p)

     t  Time until a collision
     p  Collision probability for UEID size
     k  Database size

   +---------------------+---------------+--------------+--------------+
   | Database Size       | 128-bit UEID  | 192-bit UEID | 256-bit UEID |
   +---------------------+---------------+--------------+--------------+
   | trillion (10^12)    | 60,000 years  | 10^24 years  | 10^44 years  |
   | quadrillion (10^15) | 8 seconds     | 10^14 years  | 10^34 years  |
   | 100 quadrillion     | 8             | 10^11 years  | 10^31 years  |
   | (10^17)             | microseconds  |              |              |
   +---------------------+---------------+--------------+--------------+

   Clearly, 128 bits is enough for the near future thus the requirement
   that UEIDs be a minimum of 128 bits.

   There is no requirement for 256 bits today as quadrillion-record
   databases are not expected in the near future and because this time-
   to-collision calculation is a very worst case.  A future update of
   the standard may increase the requirement to 256 bits, so there is a
   requirement that implementations be able to receive 256-bit UEIDs.

B.2.  No Use of UUID

   A UEID is not a UUID [RFC4122] by conscious choice for the following
   reasons.

   UUIDs are limited to 128 bits which may not be enough for some future
   use cases.

   Today, cryptographic-quality random numbers are available from common
   CPUs and hardware.  This hardware was introduced between 2010 and
   2015.  Operating systems and cryptographic libraries give access to
   this hardware.  Consequently, there is little need for
   implementations to construct such random values from multiple sources
   on their own.

   Version 4 UUIDs do allow for use of such cryptographic-quality random
   numbers, but do so by mapping into the overall UUID structure of time
   and clock values.  This structure is of no value here yet adds
   complexity.  It also slightly reduces the number of actual bits with
   entropy.

   UUIDs seem to have been designed for scenarios where the implementor
   does not have full control over the environment and uniqueness has to
   be constructed from identifiers at hand.  UEID takes the view that
   hardware, software and/or manufacturing process directly implement
   UEID in a simple and direct way.  It takes the view that
   cryptographic quality random number generators are readily available
   as they are implemented in commonly used CPU hardware.

Appendix C.  EAT Relation to IEEE.802.1AR Secure Device Identity (DevID)

   This section describes several distinct ways in which an IEEE IDevID
   [IEEE.802.1AR] relates to EAT, particularly to UEID and SUEID.

   [IEEE.802.1AR] orients around the definition of an implementation
   called a "DevID Module."  It describes how IDevIDs and LDevIDs are
   stored, protected and accessed using a DevID Module.  A particular
   level of defense against attack that should be achieved to be a DevID
   is defined.  The intent is that IDevIDs and LDevIDs are used with an
   open set of network protocols for authentication and such.  In these
   protocols the DevID secret is used to sign a nonce or similar to
   proof the association of the DevID certificates with the device.

   By contrast, EAT defines network protocol for proving trustworthiness
   to a Relying Party, the very thing that is not defined in
   [IEEE.802.1AR].  Nor does not give details on how keys, data and such
   are stored protected and accessed.  EAT is intended to work with a
   variety of different on-device implementations ranging from minimal
   protection of assets to the highest levels of asset protection.  It
   does not define any particular level of defense against attack,
   instead providing a set of security considerations.

   EAT and DevID can be viewed as complimentary when used together or as
   competing to provide a device identity service.

C.1.  DevID Used With EAT

   As just described, EAT defines a network protocol and [IEEE.802.1AR]
   doesn't.  Vice versa, EAT doesn't define a an device implementation
   and DevID does.

   Hence, EAT can be the network protocol that a DevID is used with.
   The DevID secret becomes the attestation key used to sign EATs.  The
   DevID and its certificate chain become the Endorsement sent to the
   Verifier.

   In this case the EAT and the DevID are likely to both provide a
   device identifier (e.g. a serial number).  In the EAT it is the UEID
   (or SUEID).  In the DevID (used as an endorsement), it is a device
   serial number included in the subject field of the DevID certificate.
   It is probably a good idea in this use for them to be the same serial
   number or for the UEID to be a hash of the DevID serial number.

C.2.  How EAT Provides an Equivalent Secure Device Identity

   The UEID, SUEID and other claims like OEM ID are equivalent to the
   secure device identity put into the subject field of a DevID
   certificate.  These EAT claims can represent all the same fields and
   values that can be put in a DevID certificate subject.  EAT
   explicitly and carefully defines a variety of useful claims.

   EAT secures the conveyance of these claims by having them signed on
   the device by the attestation key when the EAT is generated.  EAT
   also signs the nonce that gives freshness at this time.  Since these
   claims are signed for every EAT generated, they can include things
   that vary over time like GPS location.

   DevID secures the device identity fields by having them signed by the
   manufacturer of the device sign them into a certificate.  That
   certificate is created once during the manufacturing of the device
   and never changes so the fields cannot change.

   So in one case the signing of the identity happens on the device and
   the other in a manufacturing facility, but in both cases the signing
   of the nonce that proves the binding to the actual device happens on
   the device.

   While EAT does not specify how the signing keys, signature process
   and storage of the identity values should be secured against attack,
   an EAT implementation may have equal defenses against attack.  One
   reason EAT uses CBOR is because it is simple enough that a basic EAT
   implementation can be constructed entirely in hardware.  This allows
   EAT to be implemented with the strongest defenses possible.

C.3.  An X.509 Format EAT

   It is possible to define a way to encode EAT claims in an X.509
   certificate.  For example, the EAT claims might be mapped to X.509 v3
   extensions.  It is even possible to stuff a whole CBOR-encoded
   unsigned EAT token into a X.509 certificate.

   If that X.509 certificate is an IDevID or LDevID, this becomes
   another way to use EAT and DevID together.

   Note that the DevID must still be used with an authentication
   protocol that has a nonce or equivalent.  The EAT here is not being
   used as the protocol to interact with the rely party.

C.4.  Device Identifier Permanence

   In terms of permanence, an IDevID is similar to a UEID in that they
   do not change over the life of the device.  They cease to exist only
   when the device is destroyed.

   An SUEID is similar to an LDevID.  They change on device life-cycle
   events.

   [IEEE.802.1AR] describes much of this permanence as resistant to
   attacks that seek to change the ID.  IDevID permanence can be
   described this way because [IEEE.802.1AR] is oriented around the
   definition of an implementation with a particular level of defense
   against attack.

   EAT is not defined around a particular implementation and must work
   on a range of devices that have a range of defenses against attack.
   EAT thus can't be defined permanence in terms of defense against
   attack.  EAT's definition of permanence is in terms of operations and
   device lifecycle.

Appendix D.  Changes from Previous Drafts

   The following is a list of known changes from the previous drafts.
   This list is non-authoritative.  It is meant to help reviewers see
   the significant differences.

D.1.  From draft-rats-eat-01

   o  Added UEID design rationale appendix

D.2.  From draft-mandyam-rats-eat-00

   This is a fairly large change in the orientation of the document, but
   no new claims have been added.

   o  Separate information and data model using CDDL.

   o  Say an EAT is a CWT or JWT

   o  Use a map to structure the boot_state and location claims

D.3.  From draft-ietf-rats-eat-01

   o  Clarifications and corrections for OEMID claim

   o  Minor spelling and other fixes
   o  Add the nonce claim, clarify jti claim

D.4.  From draft-ietf-rats-eat-02

   o  Roll all EUIs back into one UEID type

   o  UEIDs can be one of three lengths, 128, 192 and 256.

   o  Added appendix justifying UEID design and size.

   o  Submods part now includes nested eat tokens so they can be named
      and there can be more tha one of them

   o  Lots of fixes to the CDDL

   o  Added security considerations

D.5.  From draft-ietf-rats-eat-03

   o  Split boot_state into secure-boot and debug-disable claims

   o  Debug disable is an enumerated type rather than Booleans

D.6.  From draft-ietf-rats-eat-04

   o  Change IMEI-based UEIDs to be encoded as a 14-byte string

   o  CDDL cleaned up some more

   o  CDDL allows for JWTs and UCCSs

   o  CWT format submodules are byte string wrapped

   o  Allows for JWT nested in CWT and vice versa

   o  Allows UCCS (unsigned CWTs) and JWT unsecured tokens

   o  Clarify tag usage when nesting tokens

   o  Add section on key inclusion

   o  Add hardware version claims

   o  Collected CDDL is now filled in.  Other CDDL corrections.

   o  Rename debug-disable to debug-status; clarify that it is not
      extensible

   o  Security level claim is not extensible

   o  Improve specification of location claim and added a location
      privacy section

   o  Add intended use claim

D.7.  From draft-ietf-rats-eat-05

   o  CDDL format issues resolved

   o  Corrected reference to Location Privacy section

D.8.  From draft-ietf-rats-eat-06

   o  Added boot-seed claim

   o  Rework CBOR interoperability section

   o  Added profiles claim and section

D.9.  From draft-ietf-rats-eat-07

   o  Filled in IANA and other sections for possible preassignment of
      Claim Keys for well understood claims

D.10.  From draft-ietf-rats-eat-08

   o  Change profile claim to be either a URL or an OID rather than a
      test string

D.11.  From draft-ietf-rats-eat-09

   o  Add SUEIDs

   o  Add appendix comparing IDevID to EAT

   o  Added section on use for Evidence and Attestation Results

   o  Fill in the key ID and endorsements identificaiton section

   o  Remove origination claim as it is replaced by key IDs and
      endorsements

   o  Added manifests and software evidence claims

   o  Add string labels non-claim labels for use with JSON (e.g. labels
      for members of location claim)

   o  EAN-13 HW versions are no longer a separate claim.  Now they are
      folded in as a CoSWID version scheme.

D.12.  From draft-ietf-rats-eat-10

   o  Hardware version is made into an array of two rather than two
      claims

   o  Corrections and wording improvements for security levels claim

   o  Add swresults claim

   o  Add dloas claim - Digitial Letter of Approvals, a list of
      certifications

   o  CDDL for each claim no longer in a separate sub section

   o  Consistent use of terminology from RATS architecture document

   o  Consistent use of terminology from CWT and JWT documents

   o  Remove operating model and procedures; refer to CWT, JWT and RATS
      architecture instead

   o  Some reorganization of Section 1

   o  Moved a few references, including RATS Architecture, to
      informative.

   o  Add detached submodule digests and detached eat bundles (DEBs)

   o  New simpler and more universal scheme for identifying the encoding
      of a nested token

   o  Made clear that CBOR and JSON are only mixed when nesting a token
      in another token

   o  Clearly separate CDDL for JSON and CBOR-specific data items

   o  Define UJCS (unsigned JWTs)

   o  Add CDDL for a general Claims-Set used by UCCS, UJCS, CWT, JWT and
      EAT

   o  Top level CDDL for CWT correctly refers to COSE

   o  OEM ID is specifically for HW, not for SW
   o  HW OEM ID can now be a PEN

   o  HW OEM ID can now be a 128-bit random number

   o  Expand the examples section

   o  Add software and version claims as easy / JSON alternative to
      CoSWID

D.13.  From draft-ietf-rats-eat-11

   o  Add HW model claim

   o  Change reference for CBOR OID draft to RFC 9090

   o  Correct the iat claim in some examples

   o  Make HW Version just one claim rather than 3 (device, board and
      chip)

   o  Remove CDDL comments from CDDL blocks

   o  More clearly define "entity" and use it more broadly, particularly
      instead of "device"

   o  Re do early allocation of CBOR labels since last one didn't
      complete correctly

   o  Lots of rewording and tightening up of section 1

   o  Lots of wording improvements in section 3, particularly better use
      of normative language

   o  Improve wording in submodules section, particularly how to
      distinguish types when decoding

   o  Remove security-level from early allocation

   o  Add boot odometer claim

   o  Add privacy considerations for replay protection

Authors' Addresses

   Laurence Lundblade
   Security Theory LLC

   EMail: lgl@securitytheory.com
   Giridhar Mandyam
   Qualcomm Technologies Inc.
   5775 Morehouse Drive
   San Diego, California
   USA

   Phone: +1 858 651 7200
   EMail: mandyam@qti.qualcomm.com

   Jeremy O'Donoghue
   Qualcomm Technologies Inc.
   279 Farnborough Road
   Farnborough  GU14 7LS
   United Kingdom

   Phone: +44 1252 363189
   EMail: jodonogh@qti.qualcomm.com