Internet DRAFT - draft-ietf-rats-eat-media-type
draft-ietf-rats-eat-media-type
Remote ATtestation ProcedureS L. Lundblade
Internet-Draft Security Theory LLC
Intended status: Standards Track H. Birkholz
Expires: 10 May 2024 Fraunhofer SIT
T. Fossati
Linaro
7 November 2023
EAT Media Types
draft-ietf-rats-eat-media-type-05
Abstract
Payloads used in Remote Attestation Procedures may require an
associated media type for their conveyance, for example when used in
RESTful APIs.
This memo defines media types to be used for Entity Attestation
Tokens (EAT).
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the Remote ATtestation
ProcedureS Working Group mailing list (rats@ietf.org), which is
archived at https://mailarchive.ietf.org/arch/browse/rats/.
Source for this draft and an issue tracker can be found at
https://github.com/thomas-fossati/draft-eat-mt.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 10 May 2024.
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Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. EAT Types . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. A Media Type Parameter for EAT Profiles . . . . . . . . . . . 4
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. +cwt Structured Syntax Suffix . . . . . . . . . . . . . . 6
6.1.1. Registry Contents . . . . . . . . . . . . . . . . . . 6
6.2. Media Types . . . . . . . . . . . . . . . . . . . . . . . 6
6.3. application/eat+cwt Registration . . . . . . . . . . . . 7
6.4. application/eat+jwt Registration . . . . . . . . . . . . 8
6.5. application/eat-bun+cbor Registration . . . . . . . . . . 8
6.6. application/eat-bun+json Registration . . . . . . . . . . 9
6.7. application/eat-ucs+cbor Registration . . . . . . . . . . 9
6.8. application/eat-ucs+json Registration . . . . . . . . . . 10
6.9. Content-Format . . . . . . . . . . . . . . . . . . . . . 10
7. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. -04 . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.2. -03 . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.3. -02 . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.4. -01 . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . 13
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
Payloads used in Remote Attestation Procedures [RATS-Arch] may
require an associated media type for their conveyance, for example
when used in RESTful APIs (Figure 1).
.----. .----------. .----------.
| RP | | Attester | | Verifier |
'-+--' '----+-----' '-----+----'
| | POST /verify |
| | EAT(Evidence) |
| +--------------------------->|
| | 200 OK |
| | EAT(Attestation Results) |
| |<---------------------------+
| POST /auth | |
| EAT(Attestation Results) | |
|<---------------------------+ |
| 201 Created | |
+--------------------------->| |
| | |
| | |
Figure 1: Conveying RATS conceptual messages in REST APIs using EAT
This memo defines media types to be used for Entity Attestation Token
(EAT) [EAT] payloads independently of the RATS Conceptual Message in
which they manifest themselves. The objective is to give protocol,
API and application designers a number of readily available and
reusable media types for integrating EAT-based messages in their
flows, for example when using HTTP [BUILD-W-HTTP] or CoAP [REST-IoT].
1.1. Requirements Language
This document uses the terms and concepts defined in [RATS-Arch].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. EAT Types
Figure 2 illustrates the six EAT wire formats and how they relate to
each other. [EAT] defines four of them (CWT, JWT and Detached EAT
Bundle in its JSON and CBOR flavours), whilst [UCCS] defines the
remaining two: UCCS and UJCS.
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.-----.
.----+ UJCS |<-------------------------.
| '-----' |
| |
| .-----. |
+-----+ UCCS |<-----------------------. |
| '-----' | |
| | |
| .------. | |
+-----+ JWT |<------. | |
| '------' .--+---. | |
| | Crypto |<------. | |
| .------. '--+---' | | |
+-----+ CWT |<------' | | |
| '------' .---+-+-+----.
| | Claims-Set +--.
| .------. '---+---+----' |
+-----+ BUN-J |<------. | ^ | v
| '------' .--+---. | | | .------.
| | Bundle |<------' | | | Digest |
| .------. '--+---' | v '--+---'
+-----+ BUN-C |<------' ^ .---+----. |
| '------' | | submod |<---'
| | '--------'
v | ^
.--------------. | |
| Nested-Token +-----------------+------------'
'--------------'
.-------. .---------. .------.
Legenda: | Process | | Wire Fmt | | CDDL |
'-------' '---------' '------'
Figure 2: EAT Types
3. A Media Type Parameter for EAT Profiles
EAT is an open and flexible format. To improve interoperability,
Section 6 of [EAT] defines the concept of EAT profiles. Profiles are
used to constrain the parameters that producers and consumers of a
specific EAT profile need to understand in order to interoperate.
For example: the number and type of claims, which serialisation
format, the supported signature schemes, etc. EATs carry an in-band
profile identifier using the eat_profile claim (see Section 4.3.2 of
[EAT]). The value of the eat_profile claim is either an OID or a
URI.
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The media types defined in this document include an optional
eat_profile parameter that can be used to mirror the homonymous claim
of the transported EAT. Exposing the EAT profile at the API layer
allows API routers to dispatch payloads directly to the profile-
specific processor without having to snoop into the request bodies.
This design also provides a finer-grained and scalable type system
that matches the inherent extensibility of EAT. The expectation
being that a certain EAT profile automatically obtains a media type
derived from the base (e.g., application/eat+cwt) by populating the
eat_profile parameter with the corresponding OID or URL.
4. Examples
The example in Figure 3 illustrates the usage of EAT media types for
transporting attestation evidence as well as negotiating the
acceptable format of the attestation result.
# NOTE: '\' line wrapping per RFC 8792
POST /challenge-response/v1/session/1234567890 HTTP/1.1
Host: verifier.example
Accept: application/eat+cwt; eat_profile="tag:ar4si.example,2021"
Content-Type: application/eat+cwt; \
eat_profile="tag:evidence.example,2022"
[ CBOR-encoded EAT w/ eat_profile="tag:evidence.example,2022" ]
Figure 3: Example REST Verification API (request)
The example in Figure 4 illustrates the usage of EAT media types for
transporting attestation results.
# NOTE: '\' line wrapping per RFC 8792
HTTP/1.1 200 OK
Content-Type: application/eat+cwt; \
eat_profile="tag:ar4si.example,2021"
[ CBOR-encoded EAT w/ eat_profile="tag:ar4si.example,2021" ]
Figure 4: Example REST Verification API (response)
In both cases, a tag URI [RFC4151] identifying the profile is carried
as an explicit parameter.
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5. Security Considerations
The security consideration of [EAT] and [UCCS] apply in full.
6. IANA Considerations
// RFC Editor: please replace RFCthis with this RFC number and remove
// this note.
6.1. +cwt Structured Syntax Suffix
IANA is requested to register the +cwt structured syntax suffix in
the "Structured Syntax Suffixes" registry
[IANA.media-type-structured-suffix] in the manner described in
[MediaTypes], which can be used to indicate that the media type is
encoded as a CWT.
6.1.1. Registry Contents
Name: CBOR Web Token (CWT)
+suffix: +cwt
References: [CWT]
Encoding Considerations: binary
Interoperability Considerations: N/A
Fragment Identifier Considerations: The syntax and semantics of
fragment identifiers specified for +cwt SHOULD be as specified for
application/cwt. (At publication of this document, there is no
fragment identification syntax defined for application/cwt.)
Security Considerations: See Section 8 of [CWT]
Contact: RATS WG mailing list (rats@ietf.org), or IETF Security Area
(saag@ietf.org)
Author/Change Controller: Remote ATtestation ProcedureS (RATS)
Working Group. The IETF has change control over this
registration.
6.2. Media Types
IANA is requested to add the following media types to the "Media
Types" registry [IANA.media-types].
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+==============+=====================+======================+
| Name | Template | Reference |
+==============+=====================+======================+
| EAT CWT | application/eat+cwt | RFCthis, Section 6.3 |
+--------------+---------------------+----------------------+
| EAT JWT | application/eat+jwt | RFCthis, Section 6.4 |
+--------------+---------------------+----------------------+
| Detached EAT | application/eat- | RFCthis, Section 6.5 |
| Bundle CBOR | bun+cbor | |
+--------------+---------------------+----------------------+
| Detached EAT | application/eat- | RFCthis, Section 6.6 |
| Bundle JSON | bun+json | |
+--------------+---------------------+----------------------+
| EAT UCCS | application/eat- | RFCthis, Section 6.7 |
| | ucs+cbor | |
+--------------+---------------------+----------------------+
| EAT UJCS | application/eat- | RFCthis, Section 6.8 |
| | ucs+json | |
+--------------+---------------------+----------------------+
Table 1: New Media Types
6.3. application/eat+cwt Registration
Type name: application
Subtype name: eat+cwt
Required parameters: n/a
Optional parameters: "eat_profile" (EAT profile in string format.
OIDs MUST use the dotted-decimal notation. The parameter value is
case-insensitive.)
Encoding considerations: binary
Security considerations: Section 5 of RFCthis
Interoperability considerations: n/a
Published specification: Section 6.2 of RFCthis
Applications that use this media type: Attesters, Verifiers,
Endorsers and Reference-Value providers, Relying Parties that need
to transfer EAT payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration:
// maybe
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6.4. application/eat+jwt Registration
Type name: application
Subtype name: eat+jwt
Required parameters: n/a
Optional parameters: "eat_profile" (EAT profile in string format.
OIDs MUST use the dotted-decimal notation. The parameter value is
case-insensitive.)
Encoding considerations: 8bit
Security considerations: Section 5 of RFCthis
Interoperability considerations: n/a
Published specification: Section 6.2 of RFCthis
Applications that use this media type Attesters, Verifiers,
Endorsers and Reference-Value providers, Relying Parties that need
to transfer EAT payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration:
// maybe
6.5. application/eat-bun+cbor Registration
Type name: application
Subtype name: eat-bun+cbor
Required parameters: n/a
Optional parameters: "eat_profile" (EAT profile in string format.
OIDs MUST use the dotted-decimal notation. The parameter value is
case-insensitive.)
Encoding considerations: binary
Security considerations: Section 5 of RFCthis
Interoperability considerations: n/a
Published specification: Section 6.2 of RFCthis
Applications that use this media type: Attesters, Verifiers,
Endorsers and Reference-Value providers, Relying Parties that need
to transfer EAT payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration:
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// maybe
6.6. application/eat-bun+json Registration
Type name: application
Subtype name: eat-bun+json
Required parameters: n/a
Optional parameters: "eat_profile" (EAT profile in string format.
OIDs MUST use the dotted-decimal notation. The parameter value is
case-insensitive.)
Encoding considerations: Same as [RFC7159]
Security considerations: Section 5 of RFCthis
Interoperability considerations: n/a
Published specification: Section 6.2 of RFCthis
Applications that use this media type Attesters, Verifiers,
Endorsers and Reference-Value providers, Relying Parties that need
to transfer EAT payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration:
// maybe
6.7. application/eat-ucs+cbor Registration
Type name: application
Subtype name: eat-ucs+cbor
Required parameters: n/a
Optional parameters: "eat_profile" (EAT profile in string format.
OIDs MUST use the dotted-decimal notation. The parameter value is
case-insensitive.)
Encoding considerations: binary
Security considerations: Section 5 of RFCthis
Interoperability considerations: n/a
Published specification: Section 6.2 of RFCthis
Applications that use this media type: Attesters, Verifiers,
Endorsers and Reference-Value providers, Relying Parties that need
to transfer EAT payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
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Author/Change controller: IETF
Provisional registration:
// maybe
6.8. application/eat-ucs+json Registration
Type name: application
Subtype name: eat-ucs+json
Required parameters: n/a
Optional parameters: "eat_profile" (EAT profile in string format.
OIDs MUST use the dotted-decimal notation. The parameter value is
case-insensitive.)
Encoding considerations: Same as [RFC7159]
Security considerations: Section 5 of RFCthis
Interoperability considerations: n/a
Published specification: Section 6.2 of RFCthis
Applications that use this media type Attesters, Verifiers,
Endorsers and Reference-Value providers, Relying Parties that need
to transfer EAT payloads over HTTP(S), CoAP(S), and other
transports.
Fragment identifier considerations: n/a
Person & email address to contact for further information: RATS WG
mailing list (rats@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration:
// maybe
6.9. Content-Format
| *Issue*: for symmetry reasons we may need a way to pass the
| profile information when using content formats too. Early
| proposal for a new CoAP option:
| [I-D.fossati-core-parametrized-cf]
IANA is requested to register a Content-Format number in the "CoAP
Content-Formats" sub-registry, within the "Constrained RESTful
Environments (CoRE) Parameters" Registry [IANA.core-parameters], as
follows:
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+==========================+================+======+===========+
| Content-Type | Content Coding | ID | Reference |
+==========================+================+======+===========+
| application/eat+cwt | - | TBD1 | RFCthis |
+--------------------------+----------------+------+-----------+
| application/eat+jwt | - | TBD2 | RFCthis |
+--------------------------+----------------+------+-----------+
| application/eat-bun+cbor | - | TBD3 | RFCthis |
+--------------------------+----------------+------+-----------+
| application/eat-bun+json | - | TBD4 | RFCthis |
+--------------------------+----------------+------+-----------+
| application/eat-ucs+cbor | - | TBD5 | RFCthis |
+--------------------------+----------------+------+-----------+
| application/eat-ucs+json | - | TBD6 | RFCthis |
+--------------------------+----------------+------+-----------+
Table 2: New Content-Formats
TBD1..6 are to be assigned from the space 256..999.
In the registry as defined by Section 12.3 of [CoAP] at the time of
writing, the column "Content-Type" is called "Media type" and the
column "Content Coding" is called "Encoding".
// RFC editor: please remove this paragraph.
7. Changelog
// RFC editor: please remove this section
7.1. -04
* Early IANA review
7.2. -03
* Update references
7.3. -02
* Update references
* Register +cwt SSS (Issue#14 (https://github.com/ietf-rats-wg/
draft-eat-mt/issues/14))
* Move from eat-jwt to eat+jwt (Issue#14 (https://github.com/ietf-
rats-wg/draft-eat-mt/issues/14))
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* Move from eat-cwt to eat+cwt (Issue#14 (https://github.com/ietf-
rats-wg/draft-eat-mt/issues/14))
7.4. -01
* Rename profile to eat_profile for consistency with EAT (Issue#4
(https://github.com/ietf-rats-wg/draft-eat-mt/issues/4))
* The DEB acronym is gone: shorthand is now "bun" from bundle
(Issue#8 (https://github.com/ietf-rats-wg/draft-eat-mt/issues/8))
* Incorporate editorial suggestions from Carl and Dave (Issue#7
(https://github.com/ietf-rats-wg/draft-eat-mt/issues/7), Issue#9
(https://github.com/ietf-rats-wg/draft-eat-mt/issues/9))
8. References
8.1. Normative References
[CoAP] 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>.
[CWT] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/rfc/rfc8392>.
[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-22, 14
October 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-eat-22>.
[IANA.core-parameters]
IANA, "Constrained RESTful Environments (CoRE)
Parameters",
<http://www.iana.org/assignments/core-parameters>.
[IANA.media-type-structured-suffix]
IANA, "Structured Syntax Suffixes",
<http://www.iana.org/assignments/media-type-structured-
suffix>.
[IANA.media-types]
IANA, "Media Types",
<http://www.iana.org/assignments/media-types>.
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[MediaTypes]
Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/rfc/rfc6838>.
[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>.
[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/rfc/rfc7159>.
[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>.
[UCCS] Birkholz, H., O'Donoghue, J., Cam-Winget, N., and C.
Bormann, "A CBOR Tag for Unprotected CWT Claims Sets",
Work in Progress, Internet-Draft, draft-ietf-rats-uccs-06,
2 August 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-rats-uccs-06>.
8.2. Informative References
[BUILD-W-HTTP]
Nottingham, M., "Building Protocols with HTTP", BCP 56,
RFC 9205, June 2022.
[I-D.fossati-core-parametrized-cf]
Fossati, T. and H. Birkholz, "Parametrized Content-Format
for CoAP", Work in Progress, Internet-Draft, draft-
fossati-core-parametrized-cf-01, 17 October 2022,
<https://datatracker.ietf.org/doc/html/draft-fossati-core-
parametrized-cf-01>.
[RATS-Arch]
Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote ATtestation procedureS (RATS)
Architecture", RFC 9334, DOI 10.17487/RFC9334, January
2023, <https://www.rfc-editor.org/rfc/rfc9334>.
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[REST-IoT] Keränen, A., Kovatsch, M., and K. Hartke, "Guidance on
RESTful Design for Internet of Things Systems", Work in
Progress, Internet-Draft, draft-irtf-t2trg-rest-iot-12, 25
July 2023, <https://datatracker.ietf.org/doc/html/draft-
irtf-t2trg-rest-iot-12>.
[RFC4151] Kindberg, T. and S. Hawke, "The 'tag' URI Scheme",
RFC 4151, DOI 10.17487/RFC4151, October 2005,
<https://www.rfc-editor.org/rfc/rfc4151>.
Acknowledgments
Thank you Carl Wallace, Dave Thaler, Michael Richardson for your
comments and suggestions.
Authors' Addresses
Laurence Lundblade
Security Theory LLC
Email: lgl@securitytheory.com
Henk Birkholz
Fraunhofer Institute for Secure Information Technology
Rheinstrasse 75
64295 Darmstadt
Germany
Email: henk.birkholz@sit.fraunhofer.de
Thomas Fossati
Linaro
Email: thomas.fossati@linaro.org
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