[Seat] Re: New Version Notification for draft-mihalcea-seat-use-cases-02.txt

[Markus Rudy <[e-mail]>]

Hi Henk,

You may be looking for the secure channels implemented by Project Oak: https://github.com/project-oak/oak/tree/main/oak_session.

Cheers, Markus

From: Henk Birkholz <[e-mail]>
Date: Monday, 11. May 2026 at 14:14
To: Muhammad Usama Sardar <[e-mail]>
Cc: Yaron Sheffer <[e-mail]>; Nathanael Ritz <[e-mail]>; [e-mail] <[e-mail]>; [e-mail] <[e-mail]>
Subject: [Seat] Re: New Version Notification for draft-mihalcea-seat-use-cases-02.txt

On 11.05.26 13:57, Muhammad Usama Sardar wrote:
> Hi Henk,
>
> Thank you for follow-up.
>
> Please note that all claims I make are to the best of my knowledge,
> understanding, and belief at the time of issuance of these claims. It is
> certainly possible that I may be missing something, or may have
> misunderstood something, or that some claims may become stale with time
> or deeper research. If you know of something which contradicts my
> claims, please provide substantive evidence.
>
> Please also note that we do have members from Google on this list.
>
> I would like to make another claim+plea: RATS cannot fly without SEAT --
> SEAT provides the aeroplane for RATS to fly. That is to say, we need
> more of your contributions in SEAT. 🙂
>
> Hope the following helps. Happy to clarify further if required.
>
> On 11.05.26 12:21, Henk Birkholz wrote:
>> On 06.05.26 12:59, Muhammad Usama Sardar wrote:
>>>> As an individual, I find an assertion, such as "a large part of the
>>>> industry switching to post HS", to be bit premature, tbh.
>>>
>>> I would note that you are misquoting me. I find that weird because
>>> you are not even paraphrasing; you have put it in quotes as if I said
>>> it. I rather said:
>>>
>>>      "A large part of the industry has started switching or planning
>>> to switch to post-handshake attestation."
>>>
>>> To name a few meeting my statement:
>>>
>>>   * Google
>>>   * Microsoft
>>>   * SCONE
>>>   * GA4GH
>>>   * Elixir Europe
>>>   * Edgeless Systems
>>>   * Zama
>>>   * CNCF Confidential Containers
>>>   * Cocos AI
>>>   * GENXT
>>>   * Pacific Analytics
>>>   * JetBrains
>>>   * Nebius
>>>   * Flashbots
>>
>> I apologize. I rarely do this.
> No problem at all; I appreciate the apology. I only highlighted the
> distinction because the change in wording significantly shifts the
> technical meaning.
>> But in the light of your many recent claims across various lists - and
>> me being a little bit familiar with Microsoft and Google: could you
>> please highlight were Google or Microsoft have "started switching or
>> planning to switch to post-handshake attestation"? I understand that
>> both are big companies and thereby anyone might miss something, but if
>> you could substantiate those claims, I think it would be in the
>> interest of everyone here.
>
> Sure.
>
> Google: please see [6]. My claim is also based on more recent personal
> discussions in Tokyo with Tiziano Santoro and his team after my talk --
> see recordings in [1] -- at Linux Plumber's Conference 2025. Please note
> that we are fortunate to have at least 2 members from Google on this
> list, and they will surely correct me if I am attesting to something
> which is stale since December 2025. As far as I know, Google has a very
> strong interest in formal methods (e.g., see Tiziano's work) and I am
> quite confident they will stay on high-assurance solution post-handshake
> attestation.
>
> Microsoft: please see [7]. As a member of GA4GH (i.e., without any
> hats): Microsoft is interested in the post-handshake attestation
> solution being implemented in the GA4GH.
>
> My claim on both Google and Microsoft is also based on another SDO that
> I am a member of -- unfortunately, the document is not yet public to
> share. I will share it with the list later on.
>
>>> In contrast, in meeting 125, I explicitly asked whether someone knows
>>> any other /implementation/ of intra-handshake attestation [5]. Nobody
>>> showed up.
>>>
>>> Nevertheless, if someone knows someone who is using intra-handshake
>>> attestation and has plans to continue to use it, please share so that
>>> we can inform them about the attacks.
>
> Again, as requested, if you are aware of any implementation or
> deployment of /intra/-handshake attestation, please let me know so that
> we can responsibly disclose the attacks to them. Thank you in advance
> for your support in making the systems secure.
>
>
> Best regards,
>
> -Usama
>
>>>>>> > [0]
>>>>>> https://github.com/tls-attestation/use-cases-and-properties/issues/8
>>>>>> > [1]
>>>>>> https://github.com/CCC-Attestation/formal-spec-id-crisis#upcoming-and-recent-talks-and-research-visits
>>>>>> [2]
>>>>>> https://www.researchgate.net/publication/398839141_Identity_Crisis_in_Confidential_Computing_Formal_Analysis_of_Attested_TLS
>>>>>
>>>>> [3]
>>>>> https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/platform-ownership-endorsements.html
>>>>>
>>>>> [4]
>>>>> https://mailarchive.ietf.org/arch/msg/seat/OB6ERG-aiY1xpxJEVY7xmVu2v_U/
>>> [5]
>>> https://datatracker.ietf.org/meeting/125/materials/slides-125-seat-security-analysis-00.pdf#page=6
>
> [6]
> https://github.com/CCC-Attestation/meetings/blob/main/materials/KeithMoyer_STET.pdf

TBF, I was unaware of Keith's presentation from four years ago, but that
seems to precede basically all of the discussions here. Additionally,
slide 4 seems to be an intra-handshake abstraction? I might be missing
something very obvious here, though.

>
> [7] https://www.youtube.com/watch?v=J7SibeZmQsE
>
>
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