[Seat] Re: Comments on formal analysis of relay attacks in intra-handshake attestation (CVE-2026-33697)

[Chengxin Huang <[e-mail]>]

Hello everyone,

After careful review, I would like to express strong support for the main
results of the Intra-handshake.fail paper and for considering its
accompanying code artifacts as substantive technical input for SEAT and
UFMRG.

The result I find most important is that the security of intra-handshake
attestation cannot be judged only by whether Evidence is carried during the
TLS handshake. The central question is that how strongly Evidence is bound
to the same TLS connection whose keys will protect the later application
traffic. This is a protocol-level issue, and it is directly relevant to how
SEAT evaluates candidate mechanisms for attested TLS.

The paper's analysis of binding levels is especially useful. It connects
the Evidence to different stages of the TLS key schedule and explains why
some seemingly natural binding materials are not sufficient against relay
attacks. In my view, this gives the WG a concrete basis for discussing the
paper's result instead of relying only on intuitive message-flow arguments.

I also support the methodological direction of the paper. For work that
adds attestation-related logic to or around the TLS handshake, explicit
security properties and reproducible formal artifacts are the right way
forward. Authors make it possible for the community to inspect assumptions,
test claims, compare mitigations, and improve the design on a scientific
basis.

This work is also relevant to UFMRG. It is a practical example of applying
formal analysis to an active IETF protocol-standardization problem. The
paper and code can help both the standards community and the formal-methods
community understand how formal models can be used in real protocol work,
including where such models are strong and where further analysis may still
be needed.

For these reasons, I strongly support the analysis of the paper and support
treating the paper and code as important technical input for further SEAT
and UFMRG review and refinement, as we move forward.

Best regards,
Chengxin Huang

On Mon, Jul 6, 2026 at 11:17 PM Steve <[e-mail]> wrote:

> Dear all,
>
> I am Research Analyst at Cloud Security Alliance (CSA-GCR).
>
> Because of highly severe attacks, the intra-handshake.fail paper deserves
> close attention from the SEAT WG, UFMRG and the related research community.
> From a Cloud Security Alliance community and cloud-security industry
> perspective, I strongly support bringing the paper and its supporting
> open-source code into the WG/RG discussion.
> Cloud and confidential-computing deployments rely on attestation
> mechanisms that can be implemented, audited, and operated at scale. In this
> setting, a protocol extension that adds intra-handshake attestation
> behavior affects more than message syntax. It affects implementation
> assurance, conformance testing, incident response, certification, and
> enterprise risk acceptance.
>
> The paper is therefore important industry input because it connects a
> concrete protocol-design question with formal analysis, relay-attack risk,
> and production implementation impact. Its treatment of binding mechanisms
> gives cloud providers, enterprise relying parties, security vendors, and
> governance teams a sharper basis for judging whether a proposed attestation
> transport path delivers security value proportionate to its operational
> complexity.
>
> I strongly support using the Intra-handshake.fail paper and code as a
> reference point for further SEAT and UFMRG discussion, and I encourage
> review by WG participants, UFMRG experts, confidential-computing
> implementers, and cloud-security stakeholders.
>
> Best regards,
> Steve Luo
> Research Analyst, Cloud Security Alliance (CSA-GCR)
>
> Songbo Bu <[e-mail]> 于2026年7月6日周一 22:18写道：
>
>> Hi Usama, Slava, Jean-Marie, all,
>>
>> Based on my participation in the related research discussions, I
>> appreciate sharing Intra-handshake.fail paper and code with the WG/RG and
>> strongly support using them as important technical input for the ongoing
>> SEAT discussion.
>>
>> The paper and code is valuable because it makes the discussion more
>> property-driven. In particular, I think the WG should explicitly examine
>> what security property a hybrid intra-handshake plus post-handshake
>> attestation design can satisfy that post-handshake attestation alone cannot
>> satisfy. This question is independent of any particular specification
>> proposal, and it is important for evaluating whether additional
>> intra-handshake complexity is technically justified.
>>
>> I also support the paper’s narrower focus on intra-handshake attestation.
>> Keeping the analysis scoped in this way avoids conflating different
>> attestation models and allows the WG/RG to reason more precisely about
>> binding mechanisms, relay attacks, and the relationship between Evidence
>> and the TLS connection.
>>
>> From WG charter perspective, the paper is useful because it gives the
>> community a concrete object to review, challenge, reproduce, and improve.
>> This is especially important where formal models, protocol state-machine
>> changes, and production implementations intersect.
>>
>> It helps bring the standards community and formal methods researchers
>> closer to share experience and ideas and provides UFMRG a concrete
>> methodology for protocol analysis of AI agents.
>>
>> For these reasons, I strongly support sharing this paper and code with
>> the WG/RG and encourage review from SEAT WG participants and UFMRG
>> formal-methods experts.
>>
>> Best regards,
>> Songbo Bu
>>
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