Session Date/Time: 21 Jul 2025 12:30

expat

Summary

This Birds of a Feather (BoF) session explored the need for standardizing a TLS extension enabling attestation of one or more endpoints. The session covered the problem statement, use cases (specifically confidential computing), and design space considerations. A key focus was on whether the IETF is the right place to address this problem and whether a tractable solution exists. The discussions revolved around the scope of a potential working group, including the level of TLS modification allowed, and the role of authentication versus attestation.

Key Discussion Points

Problem Statement: The need for verifiable attestation over TLS, particularly for confidential computing use cases, to provide assurance about the security and posture of the platform. Existing solutions are fragmented and lack standardization.
Use Cases: Secrets provisioning and privacy-preserving collaborative computation (e.g., data clean rooms) within confidential computing environments.
Design Space: Pre-handshake, intra-handshake, and post-handshake attestation approaches were discussed, with a focus on post-handshake solutions using TLS exported authenticators. Trade-offs between protocol changes, deployment complexity, and evidence freshness were considered.
Timeliness of Attestation: A debate emerged regarding the expected lifetime of the attestation and whether re-attestation is needed during the lifetime of a TLS session. The importance of freshness guarantees and potential for firmware changes to invalidate attestations was heavily discussed.
Authentication vs. Attestation: Clarification was sought on whether the goal is to authenticate TLS itself or authenticate an application layer protocol using TLS. The proposed solution aims to authenticate the TLS connection and provide additional security properties. The scope of authentication with relation to attestation and how it relates to TLS needed clarification in the charter.
IETF Appropriateness: Whether the IETF is the right venue for this work and how the working group will engage with Ratson TLS and other interested parties. Existing confidential computing solutions use TLS.
Charter Scope: Discussion of the need to support existing standards while exploring new solutions, discussion of whether should the working group will prefer pre -existing solutions where possible. Discussion of whether a working group would prefer to explore existing solutions spaces.
Third Party Dependencies: Clarification that authenticators are between client and server, there is no third party.
Vendor Implementations: The need to have commitments from vendors that would actually deploy implementations of a solution if a proposed standard is adopted.
TLS Binding: The need to bind the attestation to the TLS session.

Decisions and Action Items

Revise Charter Text: The proponents will revise the charter text based on the feedback received during the session, paying particular attention to scope, relationship with TLS and Rats, and privacy considerations.
Clarify Solution Scope: It was determined necessary to clarify the scope between the endpoint attestation and whether the solution would be focused on what is allowed or disallowed with less authentication.

Next Steps

The revised charter will be circulated on the [email protected] mailing list for further discussion.
The AD will evaluate whether a second BoF is needed or if the group can proceed directly to forming a working group.