EAT Measured Component
draft-fft-rats-eat-measured-component-02
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Simon Frost , Thomas Fossati , Hannes Tschofenig | ||
| Last updated | 2024-03-03 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-fft-rats-eat-measured-component-02
Remote ATtestation ProcedureS S. Frost
Internet-Draft Arm
Intended status: Standards Track T. Fossati
Expires: 4 September 2024 Linaro
H. Tschofenig
Siemens
3 March 2024
EAT Measured Component
draft-fft-rats-eat-measured-component-02
Abstract
This document defines a "measured components" format that can be used
with the EAT Measurements claim.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 4 September 2024.
Copyright Notice
Copyright (c) 2024 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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described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Information Model . . . . . . . . . . . . . . . . . . . . . . 3
4. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1.1. CWT . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1.2. JWT . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7.1. Media Types Registrations . . . . . . . . . . . . . . . . 8
7.1.1. application/measured-component+cbor . . . . . . . . . 9
7.1.2. application/measured-component+json . . . . . . . . . 9
7.2. Measured Component Content-Format Registrations . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Collected CDDL . . . . . . . . . . . . . . . . . . . 12
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . 12
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
Section 4.2.16 of [I-D.ietf-rats-eat] defines a Measurements claim
that:
"[c]ontains descriptions, lists, evidence or measurements of the
software that exists on the entity or any other measurable
subsystem of the entity."
This claim allows for different measurement formats, each identified
by a different CoAP Content-Format (Section 12.3 of [RFC7252]).
Initially, the only specified format is CoSWID of type "evidence", as
per Section 2.9.4 of [RFC9393].
This document introduces the "measured components" format that can be
used with the EAT Measurements claim in addition or as an alternative
to CoSWID.
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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.
In this document, CDDL [RFC8610] [RFC9165]
[I-D.ietf-cbor-cddl-modules] [I-D.ietf-cbor-cddl-more-control] is
used to describe the data formats.
3. Information Model
A measured component information element includes the computed digest
on the software or configuration payload, along with metadata that
helps in identifying the measurement and the authorizing entity for
component installation.
Table 1 describes the information model of a measured component.
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+================+==================================+=============+
| IE | Description | Requirement |
| | | Level |
+================+==================================+=============+
| Component Name | The name given to a measured | REQUIRED |
| | component. It is important that | |
| | this name remains consistent | |
| | across different releases to | |
| | allow for better tracking of the | |
| | same measured item across | |
| | updates. When combined with a | |
| | consistent versioning scheme, it | |
| | enables better signaling from | |
| | the appraisal procedure to the | |
| | relying parties. | |
+----------------+----------------------------------+-------------+
| Component | A value representing the | OPTIONAL |
| Version | specific release or development | |
| | version of the measured | |
| | component. Using Semantic | |
| | Versioning is RECOMMENDED. | |
+----------------+----------------------------------+-------------+
| Digest Value | Hash of the invariant part of | REQUIRED |
| | the component that is loaded in | |
| | memory at startup time. | |
+----------------+----------------------------------+-------------+
| Digest | Hash algorithm used to compute | REQUIRED |
| Algorithm | the Digest Value. | |
+----------------+----------------------------------+-------------+
| Signer | A unique identifier of the | REQUIRED |
| | entity authorizing installation | |
| | of the measured component. | |
+----------------+----------------------------------+-------------+
| Countersigners | One or more unique identifiers | OPTIONAL |
| | of further authorizing entities | |
| | for component installation | |
+----------------+----------------------------------+-------------+
Table 1: Measured Component Information Elements
4. Data Model
The data model is inspired by the "PSA software component" claim
(Section 4.4.1 of [I-D.tschofenig-rats-psa-token]), which has been
slightly refactored to take into account the recommendations about
new EAT claims design in Appendix E of [I-D.ietf-rats-eat].
The following types and semantics have been reused:
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* COSE Key Thumbprint [I-D.ietf-cose-key-thumbprint], for signer and
countersigners;
* CoSWID software name and version [RFC9393], for component name and
version;
* CoRIM digest [I-D.ietf-rats-corim], for digest value and
algorithm.
4.1. CDDL
The measured-component data item:
measured-component = [
id: component-id
measurement: corim.digest
signer: ckt
? countersigners: [ + ckt ]
]
; COSE Key Thumbprint
ckt = bytes
component-id = [
name: text
? version: version
]
;# import $version-scheme from rfc9393 as coswid
version = [
val: text
? scheme: coswid.$version-scheme
]
; eventually: ";#import digest from rfcxxxx as corim"
corim.digest = [
alg: (int / text)
val: bytes
]
The CDDL extending the EAT Measurements format:
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mc-cbor = bstr .cbor measured-component
mc-json = tstr .json measured-component
; EAT CBOR (`.feature "cbor"`)
$measurements-body-cbor /= mc-cbor ; native
$measurements-body-cbor /= tstr .b64u mc-json ; tunnel
; EAT JSON (`.feature "json"`)
$measurements-body-json /= mc-json ; native
$measurements-body-json /= tstr .b64u mc-cbor ; tunnel
4.1.1. CWT
+=====================================+====================+
| content-type (CoAP C-F equivalent) | content-format |
+=====================================+====================+
| application/measured-component+cbor | mc-cbor |
+-------------------------------------+--------------------+
| application/measured-component+json | tstr .b64u mc-json |
+-------------------------------------+--------------------+
Table 2
4.1.2. JWT
+=====================================+====================+
| content-type (CoAP C-F equivalent) | content-format |
+=====================================+====================+
| application/measured-component+json | mc-json |
+-------------------------------------+--------------------+
| application/measured-component+cbor | tstr .b64u mc-cbor |
+-------------------------------------+--------------------+
Table 3
5. Examples
(The examples are CBOR only. JSON examples will be added in a future
version of this document.)
The example in Figure 1 is a measured component with all the fields
populated.
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[
/ id / [
/ name / "boot loader X",
/ version / [
"1.2.3rc2",
16384 / semver /
]
],
/ measurement / [
/ alg / "sha-256",
/ val / h'3996003d486fb91ffb056f7d03f2b2992b215b31dbe7af4b37
3431fc7d319da3'
],
/ signer / h'492e9b676c21f6012b1ceeb9032feb4141a880797355f6675
015ec59c51ca1ec',
/ countersigners / [
h'4277bb97ba7b51577a0d38151d3e08b40bdf946753f5b5bdeb814d6ff5
7a8a5e'
]
]
Figure 1: Complete Measured Component
The example in Figure 2 is the same measured component as above but
used as the format of a measurements claim in a EAT claims-set.
Note that the example uses a CoAP Content-Format value from the
experimental range (65000), which will change to the value assigned
by IANA for the application/measured-component+cbor Content-Format.
Note also that the array contains only one measured component, but
additional entries could be added if the measured TCB is made of
multiple, individually measured components.
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{
273: [
[
65000, / using a CoAP C-F from the experimental range /
<<
[
/ id / [
/ name / "boot loader X",
/ version / [
"1.2.3rc2",
16384 / semver /
]
],
/ measurement / [
/ alg / "sha-256",
/ val / h'3996003d486fb91ffb056f7d03f2b2992b215b31db
e7af4b373431fc7d319da3'
],
/ signer / h'492e9b676c21f6012b1ceeb9032feb4141a880797
355f6675015ec59c51ca1ec',
/ countersigners / [
h'4277bb97ba7b51577a0d38151d3e08b40bdf946753f5b5bdeb
814d6ff57a8a5e'
]
]
>>
]
]
}
Figure 2: EAT Measurements Claim using a Measured Component
6. Security Considerations
TODO
7. IANA Considerations
// RFC Editor: replace "RFCthis" with the RFC number assigned to this
document.
7.1. Media Types Registrations
IANA is requested to add the following media types to the "Media
Types" registry [IANA.media-types].
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+=========+=====================================+===========+
| Name | Template | Reference |
+=========+=====================================+===========+
| mc+cbor | application/measured-component+cbor | RFCthis |
+---------+-------------------------------------+-----------+
| mc+json | application/measured-component+json | RFCthis |
+---------+-------------------------------------+-----------+
Table 4: Measured Component Media Types
7.1.1. application/measured-component+cbor
Type name: application
Subtype name: measured-component+cbor
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: binary (CBOR)
Security considerations: Section 6 of RFCthis
Interoperability considerations: n/a
Published specification: RFCthis
Applications that use this media type: Attesters, Verifiers and
Relying Parties
Fragment identifier considerations: The syntax and semantics of
fragment identifiers are as specified for "application/cbor". (No
fragment identification syntax is currently defined for
"application/cbor".)
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration: no
7.1.2. application/measured-component+json
Type name: application
Subtype name: measured-component+json
Required parameters: n/a
Optional parameters: n/a
Encoding considerations: binary (JSON is UTF-8-encoded text)
Security considerations: Section 6 of RFCthis
Interoperability considerations: n/a
Published specification: RFCthis
Applications that use this media type: Attesters, Verifiers and
Relying Parties
Fragment identifier considerations: The syntax and semantics of
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fragment identifiers are as specified for "application/json". (No
fragment identification syntax is currently defined for
"application/json".)
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration: no
7.2. Measured Component Content-Format Registrations
IANA is requested to register two Content-Format numbers in the "CoAP
Content-Formats" sub-registry, within the "Constrained RESTful
Environments (CoRE) Parameters" Registry [IANA.core-parameters], as
follows:
+=========================+================+======+===========+
| Content-Type | Content Coding | ID | Reference |
+=========================+================+======+===========+
| application/measured- | - | TBD1 | RFCthis |
| component+cbor | | | |
+-------------------------+----------------+------+-----------+
| application/measured- | - | TBD2 | RFCthis |
| component+json | | | |
+-------------------------+----------------+------+-----------+
Table 5
8. References
8.1. Normative References
[I-D.ietf-cbor-cddl-modules]
Bormann, C., "CDDL Module Structure", Work in Progress,
Internet-Draft, draft-ietf-cbor-cddl-modules-01, 18
December 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-cbor-cddl-modules-01>.
[I-D.ietf-cbor-cddl-more-control]
Bormann, C., "More Control Operators for CDDL", Work in
Progress, Internet-Draft, draft-ietf-cbor-cddl-more-
control-03, 26 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
cddl-more-control-03>.
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[I-D.ietf-cose-key-thumbprint]
Isobe, K., Tschofenig, H., and O. Steele, "CBOR Object
Signing and Encryption (COSE) Key Thumbprint", Work in
Progress, Internet-Draft, draft-ietf-cose-key-thumbprint-
04, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-cose-
key-thumbprint-04>.
[I-D.ietf-rats-corim]
Birkholz, H., Fossati, T., Deshpande, Y., Smith, N., and
W. Pan, "Concise Reference Integrity Manifest", Work in
Progress, Internet-Draft, draft-ietf-rats-corim-03, 23
October 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-corim-03>.
[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-25, 15
January 2024, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-eat-25>.
[IANA.core-parameters]
IANA, "Constrained RESTful Environments (CoRE)
Parameters",
<https://www.iana.org/assignments/core-parameters>.
[IANA.media-types]
IANA, "Media Types",
<https://www.iana.org/assignments/media-types>.
[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>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/rfc/rfc7252>.
[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>.
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[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/rfc/rfc8610>.
[RFC9165] Bormann, C., "Additional Control Operators for the Concise
Data Definition Language (CDDL)", RFC 9165,
DOI 10.17487/RFC9165, December 2021,
<https://www.rfc-editor.org/rfc/rfc9165>.
[RFC9393] Birkholz, H., Fitzgerald-McKay, J., Schmidt, C., and D.
Waltermire, "Concise Software Identification Tags",
RFC 9393, DOI 10.17487/RFC9393, June 2023,
<https://www.rfc-editor.org/rfc/rfc9393>.
8.2. Informative References
[I-D.tschofenig-rats-psa-token]
Tschofenig, H., Frost, S., Brossard, M., Shaw, A. L., and
T. Fossati, "Arm's Platform Security Architecture (PSA)
Attestation Token", Work in Progress, Internet-Draft,
draft-tschofenig-rats-psa-token-22, 21 February 2024,
<https://datatracker.ietf.org/doc/html/draft-tschofenig-
rats-psa-token-22>.
Appendix A. Collected CDDL
TODO
Appendix B. Open Issues
The list of currently open issues for this documents can be found at
https://github.com/thomas-fossati/draft-fft-rats-eat-measured-
component/issues.
// Note to RFC Editor: please remove before publication.
Acknowledgments
The authors would like to thank Carsten Bormann for comments, reviews
and suggestions.
Authors' Addresses
Simon Frost
Arm
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Email: Simon.Frost@arm.com
Thomas Fossati
Linaro
Email: Thomas.Fossati@linaro.org
Hannes Tschofenig
Siemens
Email: Hannes.Tschofenig@siemens.com
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