



Network Working Group                                     K. M. Moriarty
Internet-Draft                     Transforming Information Security LLC
Intended status: Standards Track                              M. Wiseman
Expires: 8 January 2026                                  Beyond Identity
                                                              A.J. Stein
                                                                        
                                                              C. Nelogal
                                                                    Dell
                                                             7 July 2025


 Remote Posture Assessment for Systems, Containers, and Applications at
                                 Scale
                 draft-ietf-rats-posture-assessment-03

Abstract

   This document establishes an architectural pattern whereby a remote
   attestation could be issued for a complete set of benchmarks or
   controls that are defined and grouped by an external entity,
   eliminating the need to send over individual attestations for each
   item within a benchmark or control framework.  This document
   establishes a pattern to list sets of benchmarks and controls within
   CWT and JWT formats for use as an Entity Attestation Token (EAT).
   While the discussion below pertains mostly to TPM, other Roots of
   Trust such as TCG DICE, and non-TCG defined components will also be
   included.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://ietf-rats-
   wg.github.io/draft-moriarty-attestationsets/draft-moriarty-rats-
   posture-assessment.html.  Status information for this document may be
   found at https://datatracker.ietf.org/doc/draft-ietf-rats-posture-
   assessment/.

   Discussion of this document takes place on the Remote ATtestation
   ProcedureS (rats) Working Group mailing list (mailto:rats@ietf.org),
   which is archived at https://mailarchive.ietf.org/arch/browse/rats/.
   Subscribe at https://www.ietf.org/mailman/listinfo/rats/.

   Source for this draft and an issue tracker can be found at
   https://github.com/ietf-rats-wg/draft-moriarty-attestationsets.






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Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on 8 January 2026.

Copyright Notice

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

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   4
   3.  Posture Assessment Scenarios  . . . . . . . . . . . . . . . .   4
   4.  Policy and Measurement Set Definitions  . . . . . . . . . . .   6
   5.  Supportability and Re-Attestation . . . . . . . . . . . . . .   7
   6.  Configuration Sets  . . . . . . . . . . . . . . . . . . . . .   7
   7.  Remediation . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Reuse of CBOR and JSON Web Token (CWT and JWT) Claims
           Registries  . . . . . . . . . . . . . . . . . . . . . . .   8
     9.2.  CWT and JWT Claims Registered by This Document  . . . . .   9
     9.3.  Additions to the JWT and CWT registries requested . . . .   9
     9.4.  MPS (Measurement or Policy Set) Claim . . . . . . . . . .  10
   10. Appendix A – Extended Claims Table with RoT Variants  . . . .  10



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     10.1.  A.1 – Chained Attestation and Measurement Exposure Across
            Hardware Roots of Trust  . . . . . . . . . . . . . . . .  10
     10.2.  A.2 – Extended Claims Table with DICE, Apple Secure
            Enclave, OpenTitan, and Amazon Nitro . . . . . . . . . .  11
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     11.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Posture assessment has long been desired, but has been difficult to
   achieve due to complexities of customization requirements at each
   organization.  By using policy and measurement sets that may be
   offered at various assurance levels, local assessment of evidence can
   be performed to continuously assess compliance.

   For example, the Trusted Computing Group's Trusted Platform Module
   (TPM) format and assessment method can provide this kind of
   compliance.  This and other methods employ a secured log for
   transparency on the results of the assessed evidence against expected
   values.

   In order to support continuous monitoring of posture assessment and
   integrity in an enterprise or large data center, the local
   assessments and remediation are useful to reduce load on the network
   and remote resources.  This is currently done today in measured boot
   mechanisms.

   It is useful to be able to share these results in order to gain a big
   picture view of the governance, risk, and compliance posture for a
   network.

   As such, communicating a summary result as evidence tied including a
   link to supporting logs with a remote attestation defined in an
   Entity Attestation Token (EAT) profile [I-D.ietf-rats-eat] provides a
   way to accomplish that goal.

   This level of integration, which includes the ability to remediate,
   makes posture assessment through remote attestation achievable for
   organizations of all sizes.  This is enabled through integration with
   existing toolsets and systems, built as an intrinsic capability.

   The measurement and policy grouping results summarized in an EAT
   profile may be provided by the vendor or by a neutral third party to
   enable ease of use and consistent implementations.




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   The local system or server host performs the assessment of posture
   and remediation.  This provides simpler options to enable posture
   assessment at selected levels by organizations without the need to
   have in-house expertise.

   The measurement and policy sets may also be customized, but not
   necessary to achieve posture assessment to predefined options.

   This document describes a method to use existing remote attestation
   formats and protocols.  The method described allows for defined
   profiles of policies, benchmarks, and measurements for specific
   assurance levels.  This provides transparency on posture assessment
   results summarized with remote attestations.

2.  Conventions and Definitions

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

3.  Posture Assessment Scenarios

   By way of example, the Center for Internet Security (CIS) hosts
   recommended configuration settings to secure operating systems,
   applications, and devices in CIS Benchmarks [BENCHMARKS] developed
   with industry experts.  Attestations aligned to the CIS Benchmarks or
   other configuration guide such as one of the Defense Information
   Systems Agency's Security Technical Implement Guides [STIG] could be
   used to assert the configuration meets expectations.  This has
   already been done for multiple platforms to demonstrate assurance for
   firmware according to NIST SP 800-193, Firmware Resiliency Guidelines
   [FIRMWARE].  In order to scale remote attestation, a single
   attestation for a set of benchmarks or policies being met with a link
   to the verification logs from the local assessments, is the evidence
   that may be sent to the verifier and then the relying party.  On
   traditional servers, assurance to NIST SP 800-193 is provable through
   attestation from a root of trust (RoT), using the Trusted Computing
   Group (TCG) Trusted Platform Module (TPM) chip and attestation
   formats.  However, this remains local and one knows the policies and
   measurements have been met if other functions that rely on the
   assurance are running.

   At boot, policy and measurement expectations are verified against a
   set of "golden policies" from collected evidence and are verified to
   meet expected values.  Device identity and measurements can also be
   attested at runtime.  The attestations on evidence (e.g. hash of boot



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   element) and verification of attestations are typically contained
   within a system and are limited to the control plane for management.
   The policy and measurement sets for comparison are protected to
   assure the result in the attestation verification process for boot
   element.  Event logs and PCR values may be exposed to provide
   transparency into the verified attestations.  The remote attestation
   defined in this document provides a summary of a local assessment of
   posture for managed systems and across various layers (operating
   system, application, containers) in each of these systems in a
   managed environment as evidence.  The Relying Party uses the verified
   evidence to under stand posture of interconnected operating systems,
   applications, and systems that are communicated in summary results.

   There is a balance of exposure and evidence needed to assess posture
   when providing assurance of controls and system state.  Currently, if
   using the TPM, logs and TPM PCR values may be passed to provide
   assurance of verification of attestation evidence meeting set
   requirements.  Providing the set of evidence as assurance to a policy
   set can be accomplished with a remote attestation format such as the
   Entity Attestation Token (EAT) [I-D.ietf-rats-eat] and a RESTful
   interface such as ROLIE [RFC8322] or RedFish [REDFISH].  Policy
   definition blocks may be scoped to control measurement sets, where
   the EAT profile asserts compliance to the policy or measurement block
   specified and may include claims with the log and PCR value evidence.
   Measurement and Policy sets, referenced in an EAT profile may be
   published and maintained by separate entities (e.g.  CIS Benchmarks,
   DISA STIGs).  The policy and measurement sets should be maintained
   separately even if associated with the same benchmark or control set.
   This avoids the need to transition the verifying entity to a remote
   system for individual policy and measurements which are performed
   locally for more immediate remediation as well as other functions.

   Examples of measurement and policy sets that could be defined in EAT
   profiles include, but are not limited to:

   *  Hardware attribute certificates, TCG

   *  Hardware Attribute Certificate Comparison Results, TCG

   *  Reference Integrity Measurements for firmware, TCG

   *  Operating system benchmarks at Specified Assurance Levels, CIS

   *  Application hardening Benchmarks at Specified Assurance Levels,
      CIS, DISA STIG

   *  Container security benchmarks at Specified Assurance Levels, CIS




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   Scale, ease of use, full automation, and consistency for customer
   consumption of a remote attestation function or service are essential
   toward the goal of consistently securing systems against known
   threats and vulnerabilities.  Mitigations may be baked into policy.
   Claim sets of measurements and policy verified to meet or not meet
   Endorsed values [I-D.ietf-rats-eat] are conveyed in an Entity
   Attestation Token made available to a RESTful interface in aggregate
   for the systems managed as evidence for the remote attestation.  The
   Measurement or Policy Set may be registered in the IANA registry
   created in this document (Section 9), detailing the specific
   configuration policies and measurements required to adhere or prove
   compliance to the associated document to enable interoperability.
   Levels (e.g. high, medium, low, 1, 2, 3) or vendor specific instances
   of the policy defined in code required to verify the policy and
   measurements would be registered using a name for the policy set,
   that would also be used in the reporting EAT that includes the MPS
   along with other artifacts to prove compliance.

4.  Policy and Measurement Set Definitions

   This document defines EAT claims in the JWT [RFC7519] and CWT
   [RFC8392] registries to provide attestation to a set of verified
   claims within a defined grouping.  The trustworthiness will be
   conveyed on original verified evidence as well as the attestation on
   the grouping.  The claims provide the additional information needed
   for an EAT to convey compliance to a defined policy or measurement
   set to a system or application collecting evidence on policy and
   measurement assurance, for instance a Governance, Risk, and
   Compliance (GRC) system.

   +=======+============================+====================+========+
   | Claim | Long Name                  | Claim Description  | Format |
   +=======+============================+====================+========+
   | mps   | Measurement or Policy Set  | Name for the MPS   |        |
   +-------+----------------------------+--------------------+--------+
   | lem   | Log Evidence of MPS        | Log File or URI    |        |
   +-------+----------------------------+--------------------+--------+
   | pcr   | TPM PCR Values             | URI                |        |
   +-------+----------------------------+--------------------+--------+
   | fma   | Format of MPS Attestations | Format of included |        |
   |       |                            | attestations       |        |
   +-------+----------------------------+--------------------+--------+
   | hsh   | Hash Value/Message Digest  | Hash value of      |        |
   |       |                            | claim-set          |        |
   +-------+----------------------------+--------------------+--------+

                                 Table 1




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5.  Supportability and Re-Attestation

   The remote attestation framework shall include provisions for a
   Verifier Owner and Relying Party Owner to declare an Appraisal Policy
   for Attestation Results and Evidence that allows for modification of
   the Target Environment (e.g. a product, system, or service).

   Over its lifecycle, the Target Environment may experience
   modification due to: maintenance, failures, upgrades, expansion,
   moves, etc..

   The Relying Party Owner managing the Target Environment (e.g.
   customer using the product) can chose to:

   *  Update the Appraisal Policy for Attestation Results and re-assess
      posture with this updated policy, summarizing with a remote
      attestation to the new policy or level, or

   *  Run remote attestation after modification of the Target
      Environment as an external validation, or

   *  Continue operation of the Target Environment as-is, without
      verification, potentially increasing risk

   In the case of Re-Attestation:

   *  framework needs to invalidate previous Reference Values (e.g. TPM
      PCR values and tokens),

   *  framework needs to specify an Appraisal Policy for Evidence that
      requires fresh Evidence,

   *  framework needs to maintain history or allow for history to be
      logged to enable change traceability attestation, and

   *  framework needs to notify that the previous Attestation Results
      has been invalidated

6.  Configuration Sets

   In some cases, it may be difficult to attest to configuration
   settings for the initial or subsequent attestation and verification
   processes.  The use of an expected hash value for configuration
   settings can be used to compare the attested configuration set.  In
   this case, the creator of the attestation verification measurements
   would define a set of values for which a message digest would be
   created and then signed by the attestor.  The expected measurements
   would include the expected hash value for comparison.



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   The configuration set could be the full attestation set to a
   Benchmark or a defined subset.  These configuration sets can be
   registered for general use to reduce the need to replicate the policy
   and measurement assessments by others aiming to assure at the same
   level for a benchmark or hardening guide.

   This document creates an IANA registry for this purpose, creating
   consistency between automated policy and measurement set levels and
   the systems used to collect and report aggregate views for an
   organization across systems and applications, such as a GRC platform.

7.  Remediation

   If policy and configuration settings or measurements attested do not
   meet expected values, remediation is desireable.  Automated
   remediation performed with alignment to zero trust architecture
   principles would require that the remediation be performed prior to
   any relying component executing.  The relying component would verify
   before continuing in a zero trust architecture.

   Ideally, remediation would occur on system as part of the process to
   attest to a set of attestations, similar to how attestation is
   performed for firmware in the boot process.  If automated remediation
   is not possible, an alert should be generated to allow for
   notification of the variance from expected values.

8.  Security Considerations

   This document establishes a pattern to list sets of benchmarks and
   controls within CWT and JWT formats.  The contents of the benchmarks
   and controls are out of scope for this document.  This establishes an
   architectural pattern whereby a remote attestation could be issued
   for a complete set of benchmarks or controls as defined and grouped
   by external entities, preventing the need to send over individual
   attestations for each item within a benchmark or control framework.
   This document does not add security consideration over what has been
   described in the EAT, JWT, or CWT specifications.

9.  IANA Considerations

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

   Claims defined in this document are a profile of EAT.  Like the base
   claims of EAT, the claims below 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.



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9.2.  CWT and JWT Claims Registered by This Document

   This document requests the creation of a Measurement and Policy Set
   (MPS) registry.  The MPS registry will contain the names of the
   Benchmarks, Policy sets, DISA STIGS, controls, or other groupings as
   a policy and measurement set that MAY correlate to standards
   documents containing assurance guidelines, compliance requirements,
   or other defined claim sets for verification of posture assessment to
   that MPS.  The MPS registry will include the policy definition for
   specific levels of MPS assurance to enable interoperability between
   assertions of compliance (or lack thereof) and reporting systems.

   +===============+=======================+==========================+
   | MPS Name      | MPS Description       | File with MPS definition |
   +===============+=======================+==========================+
   | Ubuntu-CIS-L1 | Ubuntu CIS Benchmark, | http:// /Ubuntu-CIS-     |
   |               | level 1 assurance     | L1.txt                   |
   +---------------+-----------------------+--------------------------+

                                 Table 2

   The MPS name includes versions or level information, allowing for
   distinct policy or measurement sets and definitions of those sets
   (including the supporting formats used to write the definitions).

9.3.  Additions to the JWT and CWT registries requested

   This document requests the following JWT claims per the specification
   requirement required for the JSON Web Token (JWT) registry defined in
   RFC7519.

        +=======+============================+====================+
        | Claim | Long Name                  | Claim Description  |
        +=======+============================+====================+
        | MPS   | Measurement or Policy Set  | Name for the MPS   |
        +-------+----------------------------+--------------------+
        | LEM   | Log Evidence of MPS        | Log File or URI    |
        +-------+----------------------------+--------------------+
        | PCR   | TPM PCR Values             | URI                |
        +-------+----------------------------+--------------------+
        | FMA   | Format of MPS Attestations | Format of included |
        |       |                            | attestations       |
        +-------+----------------------------+--------------------+
        | HSH   | Hash Value/Message Digest  | Hash value of      |
        |       |                            | claim-set          |
        +-------+----------------------------+--------------------+

                                  Table 3



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9.4.  MPS (Measurement or Policy Set) Claim

   The MPS (Measurement or Policy Set) claim identifies the policy and
   measurement set being reported.  The MPS MAY be registered to the MPS
   IANA registry.  The MPS may be specified to specific levels of
   assurance to hardening, loosening guides or benchmarks to provide
   interoperability in reporting.  The processing of this claim is
   generally application specific.  The MPS value is a case-sensitive
   string containing a StringOrURI value.  Use of this claim is
   OPTIONAL.

   This document requests the following CWT claims per the specification
   requirement required for the CBOR Web Token (CWT) registry defined in
   RFC8392.

     +=======+================+====================+================+
     | Claim | Long Name      | Claim Description  | JWT Claim Name |
     +=======+================+====================+================+
     | MPS   | Measurement or | Name for the MPS   | MPS            |
     |       | Policy Set     |                    |                |
     +-------+----------------+--------------------+----------------+
     | LEM   | Log Evidence   | Log File or URI    | LEM            |
     |       | of MPS         |                    |                |
     +-------+----------------+--------------------+----------------+
     | PCR   | TPM PCR Values | URI                | PCR            |
     +-------+----------------+--------------------+----------------+
     | FMA   | Format of MPS  | Format of included | FMA            |
     |       | Attestations   | attestations       |                |
     +-------+----------------+--------------------+----------------+
     | HSH   | Hash Value/    | Hash value of      | HSH            |
     |       | Message Digest | claim-set          |                |
     +-------+----------------+--------------------+----------------+

                                 Table 4

10.  Appendix A – Extended Claims Table with RoT Variants

10.1.  A.1 – Chained Attestation and Measurement Exposure Across
       Hardware Roots of Trust

   +=========+===========+=============+===============+==============+
   |Platform |Hardware   | Measurement | Attestation   | PCR/         |
   |         |Root of    | Chaining    | Evidence      | Measurement  |
   |         |Trust      |             |               | Exposure     |
   +=========+===========+=============+===============+==============+
   |DICE     |Minimal    | Yes         | Stage         | CDIs (not    |
   |         |hardware + |             | certificates, | standard     |
   |         |UDS        |             | attestation   | PCRs)        |



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   |         |           |             | chain         |              |
   +---------+-----------+-------------+---------------+--------------+
   |Apple    |Boot ROM & | Yes         | Internal      | Not standard |
   |         |Secure     |             | logs,         | PCRs         |
   |         |Enclave    |             | biometric/    | (internal    |
   |         |           |             | auth evidence | use)         |
   +---------+-----------+-------------+---------------+--------------+
   |OpenTitan|Open-source| Yes         | Logs,         | TPM-like     |
   |         |silicon    |             | certificates  | PCRs         |
   |         |chip       |             |               |              |
   +---------+-----------+-------------+---------------+--------------+
   |Amazon   |Nitro      | Yes         | NitroTPM      | NitroTPM     |
   |Nitro    |Security   |             | logs, AWS-    | PCRs         |
   |         |Chip       |             | signed        |              |
   |         |           |             | attestation   |              |
   +---------+-----------+-------------+---------------+--------------+
   |Nitro    |Nitro      | Yes         | AWS-signed    | Enclave PCRs |
   |Enclaves |Security   |             | attestation   |              |
   |         |Chip +     |             | tokens        |              |
   |         |Hypervisor |             |               |              |
   +---------+-----------+-------------+---------------+--------------+

                                 Table 5

10.2.  A.2 – Extended Claims Table with DICE, Apple Secure Enclave,
       OpenTitan, and Amazon Nitro

   +=========+=====+===========+=====================+=================+
   |Platform |Claim|Long Name  | Claim Description   |Format           |
   |         |     |           | (with RoT           |                 |
   |         |     |           | Mechanism)          |                 |
   +=========+=====+===========+=====================+=================+
   |DICE     |mps  |Measurement| DICE CDI lineage:   |CDI derivation   |
   |         |     |or Policy  | Minimalist          |chain;           |
   |         |     |Set        | hardware root of    |certificate-based|
   |         |     |           | trust (UDS in ROM/  |attestation      |
   |         |     |           | SoC), performs      |                 |
   |         |     |           | measured boot,      |                 |
   |         |     |           | derives Compound    |                 |
   |         |     |           | Device Identifiers  |                 |
   |         |     |           | (CDIs) at each      |                 |
   |         |     |           | boot stage,         |                 |
   |         |     |           | binding device and  |                 |
   |         |     |           | firmware state.     |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |DICE     |lem  |Log        | Implementation-     |Log file,        |
   |         |     |Evidence of| specific logs and   |attestation      |
   |         |     |MPS        | attestation         |certificate, or  |



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   |         |     |           | certificates;       |URI              |
   |         |     |           | evidence is the     |                 |
   |         |     |           | chain of CDIs and   |                 |
   |         |     |           | alias               |                 |
   |         |     |           | certificates,       |                 |
   |         |     |           | often used in TLS   |                 |
   |         |     |           | client              |                 |
   |         |     |           | authentication.     |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |DICE     |pcr  |TPM PCR    | Not applicable;     |—                |
   |         |     |Values     | DICE does not use   |                 |
   |         |     |           | TPM PCRs.           |                 |
   |         |     |           | Instead, it uses    |                 |
   |         |     |           | derived             |                 |
   |         |     |           | cryptographic       |                 |
   |         |     |           | identities (CDIs)   |                 |
   |         |     |           | per boot stage.     |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |Apple    |mps  |Measurement| Secure Enclave      |Local attestation|
   |         |     |or Policy  | root identity and   |(UID + monotonic |
   |         |     |Set        | enclave             |counter); enclave|
   |         |     |           | measurements:       |measurement logs |
   |         |     |           | Hardware root of    |                 |
   |         |     |           | trust (immutable    |                 |
   |         |     |           | Boot ROM in SoC),   |                 |
   |         |     |           | secure boot of SEP  |                 |
   |         |     |           | OS, device-unique   |                 |
   |         |     |           | UID, monotonic      |                 |
   |         |     |           | counter for anti-   |                 |
   |         |     |           | replay/rollback,    |                 |
   |         |     |           | local attestation.  |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |Apple    |lem  |Log        | SEP logs, anti-     |Internal log file|
   |         |     |Evidence of| replay/rollback     |or counter       |
   |         |     |MPS        | counters, internal  |                 |
   |         |     |           | secure boot logs    |                 |
   |         |     |           | (not externally     |                 |
   |         |     |           | exposed); used for  |                 |
   |         |     |           | local security and  |                 |
   |         |     |           | policy              |                 |
   |         |     |           | enforcement.        |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |Apple    |pcr  |TPM PCR    | Not applicable;     |—                |
   |         |     |Values     | Apple does not      |                 |
   |         |     |           | expose TPM PCRs.    |                 |
   |         |     |           | Integrity is        |                 |
   |         |     |           | enforced using      |                 |
   |         |     |           | UID, monotonic      |                 |



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   |         |     |           | counters, and       |                 |
   |         |     |           | secure boot chain.  |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |OpenTitan|mps  |Measurement| Boot-time firmware  |Hardware-backed  |
   |         |     |or Policy  | validation and      |attestation logs |
   |         |     |Set        | Creator Identity    |and certificates |
   |         |     |           | checks: Open-       |                 |
   |         |     |           | source silicon      |                 |
   |         |     |           | root of trust       |                 |
   |         |     |           | (boot ROM in        |                 |
   |         |     |           | silicon), measured  |                 |
   |         |     |           | boot, stable        |                 |
   |         |     |           | Creator Identity,   |                 |
   |         |     |           | hardware-backed     |                 |
   |         |     |           | key management,     |                 |
   |         |     |           | remote              |                 |
   |         |     |           | attestation.        |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |OpenTitan|lem  |Log        | Firmware integrity  |Certificate-based|
   |         |     |Evidence of| logs, certificate-  |attestation, log |
   |         |     |MPS        | based attestation,  |file             |
   |         |     |           | logs tied to        |                 |
   |         |     |           | Creator Identity    |                 |
   |         |     |           | and measured boot   |                 |
   |         |     |           | state.              |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |OpenTitan|pcr  |TPM PCR    | Custom attestation  |Hardware-backed  |
   |         |     |Values     | logs; supports      |boot state, TPM- |
   |         |     |           | TPM-like PCRs for   |like PCRs        |
   |         |     |           | remote              |                 |
   |         |     |           | attestation, but    |                 |
   |         |     |           | uses a stable       |                 |
   |         |     |           | Creator Identity    |                 |
   |         |     |           | rather than         |                 |
   |         |     |           | evolving device     |                 |
   |         |     |           | identity at each    |                 |
   |         |     |           | firmware layer.     |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |Amazon   |mps  |Measurement| Secure boot and     |NitroTPM PCR     |
   |Nitro    |     |or Policy  | firmware            |values, AWS-     |
   |         |     |Set        | validation: Nitro   |signed           |
   |         |     |           | Security Chip as    |attestation      |
   |         |     |           | hardware root of    |                 |
   |         |     |           | trust, NitroTPM     |                 |
   |         |     |           | provides virtual    |                 |
   |         |     |           | TPM instance with   |                 |
   |         |     |           | PCRs, measured      |                 |
   |         |     |           | boot, and remote    |                 |



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   |         |     |           | attestation for     |                 |
   |         |     |           | cloud servers and   |                 |
   |         |     |           | Nitro Enclaves.     |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |Amazon   |lem  |Log        | NitroTPM logs,      |AWS-signed       |
   |Nitro    |     |Evidence of| attestation         |attestation,     |
   |         |     |MPS        | evidence, logs      |NitroTPM log file|
   |         |     |           | signed by AWS;      |                 |
   |         |     |           | used for remote     |                 |
   |         |     |           | attestation and     |                 |
   |         |     |           | verification of     |                 |
   |         |     |           | cloud instance or   |                 |
   |         |     |           | enclave state.      |                 |
   +---------+-----+-----------+---------------------+-----------------+
   |Amazon   |pcr  |TPM PCR    | NitroTPM PCR        |Cryptographically|
   |Nitro    |     |Values     | values              |signed PCR       |
   |         |     |           | (cryptographically  |values, standard |
   |         |     |           | signed, used for    |TPM 2.0 format   |
   |         |     |           | attestation and     |                 |
   |         |     |           | sealing secrets to  |                 |
   |         |     |           | boot state);        |                 |
   |         |     |           | standard TPM 2.0    |                 |
   |         |     |           | interface for EC2   |                 |
   |         |     |           | instances and       |                 |
   |         |     |           | Nitro Enclaves.     |                 |
   +---------+-----+-----------+---------------------+-----------------+

                                  Table 6

11.  References

11.1.  Normative References

   [I-D.ietf-rats-eat]
              Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
              Wallace, "The Entity Attestation Token (EAT)", Work in
              Progress, Internet-Draft, draft-ietf-rats-eat-31, 6
              September 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-rats-eat-31>.

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

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




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   [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/rfc/rfc2119>.

   [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/rfc/rfc7519>.

   [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/rfc/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/rfc/rfc8392>.

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

11.2.  Informative References

   [BENCHMARKS]
              "Center for Internet Security Benchmarks List", n.d.,
              <https://www.cisecurity.org/cis-benchmarks>.

   [FIRMWARE] Regenscheid, A., "Platform firmware resiliency
              guidelines", National Institute of Standards and
              Technology, DOI 10.6028/nist.sp.800-193, May 2018,
              <https://doi.org/10.6028/nist.sp.800-193>.

   [REDFISH]  "Redfish Specification Version 1.20.0", n.d.,
              <https://www.dmtf.org/sites/default/files/standards/
              documents/DSP0266_1.20.0.pdf>.

   [RFC8322]  Field, J., Banghart, S., and D. Waltermire, "Resource-
              Oriented Lightweight Information Exchange (ROLIE)",
              RFC 8322, DOI 10.17487/RFC8322, February 2018,
              <https://www.rfc-editor.org/rfc/rfc8322>.

   [STIG]     "Defense Information Systems Agency Security Technical
              Implementation Guides", n.d.,
              <https://public.cyber.mil/stigs/>.






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Contributors

   Thank you to reviewers and contributors who helped to improve this
   document.  Thank you to Nick Grobelney, Dell Technologies, for your
   review and contribution to separate out the policy and measurement
   sets.  Thank you, Samant Kakarla and Huijun Xie from Dell
   Technologies, for your detailed review and corrections on boot
   process details.  Section 3 has been contributed by Rudy Bauer from
   Dell as well and an author will be added on the next revision.  IANA
   section added in version 7 by Kathleen Moriarty, expanding the claims
   registered and adding a proposed registry to define policy and
   measurement sets.  Thank you to Henk Birkholz for his review and
   edits.  Thanks to Thomas Fossati, Michael Richardson, and Eric Voit
   for their detailed reviews on the mailing list.  Thank you to A.J.
   Stein for converting the XMLMind workflow to Markdown and GitHub,
   editorial contributions, and restructuring of the document.

Authors' Addresses

   Kathleen M. Moriarty
   Transforming Information Security LLC
   MA
   United States of America
   Email: kathleen.Moriarty.ietf@gmail.com


   Monty Wiseman
   Beyond Identity
   3 Park Avenue
   NY, NY 10016
   United States of America
   Email: monty.wiseman@beyondidentity.com


   A.J. Stein
   United States of America
   Email: ajstein.standards@gmail.com
   URI:   https://orcid.org/0000-0003-1092-2642


   Chandra Nelogal
   Dell Technologies
   176 South Street
   MA 01748
   United States of America
   Email: chandra.nelogal@dell.com





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