WG Review: Remote ATtestation ProcedureS (rats)

[The IESG <[e-mail]>]

The Remote ATtestation ProcedureS (rats) WG in the Security Area of the IETF
is undergoing rechartering. The IESG has not made any determination yet. The
following draft charter was submitted, and is provided for informational
purposes only. Please send your comments to the IESG mailing list
([e-mail]) by 2022-05-21.

Remote ATtestation ProcedureS (rats)
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Current status: Active WG

Chairs:
  Ned Smith <[e-mail]>
  Nancy Cam-Winget <[e-mail]>
  Kathleen Moriarty <[e-mail]>

Assigned Area Director:
  Roman Danyliw <[e-mail]>

Security Area Directors:
  Roman Danyliw <[e-mail]>
  Paul Wouters <[e-mail]>

Mailing list:
  Address: [e-mail]
  To subscribe: https://www.ietf.org/mailman/listinfo/rats
  Archive: https://mailarchive.ietf.org/arch/browse/rats/

Group page: https://datatracker.ietf.org/group/rats/

Charter: https://datatracker.ietf.org/doc/charter-ietf-rats/

# Introduction

In network protocol exchanges, it is often the case that one entity (a
Relying Party) requires evidence about the remote peer (and system components
[RFC4949] thereof), in order to assess the trustworthiness of the peer. 
Remote attestation procedures (RATS) determine whether relying parties can
establish a level of confidence in the trustworthiness of remote peers,
called Attesters.  The objective is achieved by a two-stage appraisal
procedure facilitated by a trusted third party, called Verifier, with trusted
links to the supply chain.

The procedures for the two stages are:

* Evidence Appraisal: a Verifier applies policy and supply chain input, such
as Endorsements and References Values, to create Attestation Results from
Evidence.

* Attestation Results Appraisal: a Relying Party applies policy to
Attestation Results associated with an Attester's Evidence that originates
from a trusted Verifier. The results are trust decisions regarding the
Attester.

To improve the confidence in a system component's trustworthiness, a relying
party may require evidence about:

* system component identity,
* composition of system components, including nested components,
* roots of trust,
* an assertion/claim origination or provenance,
* manufacturing origin,
* system component integrity,
* system component configuration,
* operational state and measurements of steps which led to the operational
state, or

* other factors that could influence trust decisions.

While domain-specific attestation mechanisms such as Trusted Computing Group
(TCG) Trusted Platform Module (TPM)/TPM Software Stack (TSS), Fast Identity
Online (FIDO) Alliance attestation, and Android Keystore attestation exist,
there is no interoperable way to create and process attestation evidence to
make determinations about system components among relying parties of
different manufactures and origins.

# Goals

The WG has defined an architecture (draft-ietf-rats-architecture) for remote
attestation. The WG will standardize formats for describing evidence and
attestation results and the associated procedures and protocols to convey
evidence for appraisal to a verifier and attestation results to a relying
party. Additionally, the WG will standardize formats for endorsements and
reference values, and may apply and/or profile existing protocols (e.g.,
DTLS, CoAP, or MUD) to convey them to the verifier. Formats and protocols for
appraisal policy for evidence and appraisal policy for attestation results
are out of scope.

The WG will continue to cooperate and coordinate with other IETF WGs such as
TEEP, SUIT, CoRE, ACE, and CBOR; and work with organizations in the
community, such as the TCG, Global Platform, and the FIDO Alliance, as
appropriate.

# Program of Work

The working group will develop standards supporting interoperable remote
attestation procedures for system components. The main deliverables are as
follows:

1. Specify use cases for remote attestation (to document and achieve WG
consensus but not expected to be published as an RFC).

2. Specify augmentations to the RATS architecture
(draft-ietf-rats-architecture) in support of specific attestation techniques.

3. Standardize an information model for evidence and attestations results
scoped by the specified use-cases.

4. Standardize data models that implement and secure the defined information
model (e.g., CBOR Web Token structures [RFC8392], JSON Web Token structures
[RFC7519]).

5. If feasible, use or extend existing protocols to securely convey evidence
and attestation results, or if not, then standardize interoperable protocols
for this purpose.

6. Standardize interoperable data formats to securely declare and convey
endorsements and reference values.

Milestones:

  Jul 2022 - Call for adoption on Concise Reference Integrity and Endorsement
  Manifests

  Nov 2023 - Submit Concise Reference Integrity and Endorsement Manifests for
  publication