[Seat] Re: Regarding symbolic analysis of draft-fossati-seat-early-attestation-06

[Nathanael Ritz <[e-mail]>]

Hi,

On Sun, 9 Aug 2026 at 20:59, Songbo Bu <[e-mail]> wrote:

> [snip] My understanding is that `selfsign` is self-signed certificate for
> the
> key generated within the TEE. Evidence cannot be transmitted as it is
> in TLS 1.3, so a self-signed certificate is generated. Could you
> clarify what sense it would make to check the self-signed certificate
> at client-side? What needs to be checked before gate release is the
> signature using AK and that is correctly there in my reading
> (
> https://github.com/muhammad-usama-sardar/intra-handshake.fail/blob/819bb7f20ac458b27c9be2c91cce1e72b8b5f4f7/binder1/tls-lib-simple.pvl#L682
> ).
>

The symbolic `selfsign` parameter is a redundant modeling bug. Within the
CRT message of Usama's model, the Evidence is conveyed in the `quote`
parameter. The ephemeral signing key is the `pubEK` parameter. However, as
mentioned before, outside of introducing a modeling artifact, its presence
is generally harmless. I say this because as one may have already seen, a
query like "Property G-C2: Composition Property for Relay attack," already
demonstrates that using the CH...SH checkpoint successfully mitigates
CVE-2026-33697/EUVD-2026-16488 -- even with the modeling bug left
untouched.

On Sun, 9 Aug 2026 at 20:59, Songbo Bu <[e-mail]> wrote:

> I don't think it is helpful to downplay someone's work by calling it
> "niaeve binders". Do you really believe that tall companies like Meta
> are using what you call as "niaeve binders"? According to section 8 of
> intra-handshake.fail paper, that has gone through "extensive security
> review" (
> https://github.com/trailofbits/publications/blob/master/reviews/2025-08-meta-whatsapp-privateprocessing-securityreview.pdf
> )
> by a cybersecurity firm "Trail of Bits". In my search, Trail of Bits
> appears to be a very reputed firm. Do you really believe that a very
> reputed cybersecurity firm missed "niaeve binders" in their "extensive
> security review"?
>

Absolutely. Funny, Usama asked me the exact same thing a few weeks ago [0].
The answer to that same question remains unchanged [1]: "I highly doubt
[anyone] will be offended, if that's what you might be concerned about."

Secure systems get better with a healthy dose of collaboration between both
red teams (finding attacks) and blue teams (constructively guarding and
mitigating). Both are highly valuable to the community.To quote someone
else I spoke to in a discussion about this technology space, "it's all just
a gigantic work in progress."

Cheers,
Nathanael


>
> Best,
> Songbo
>

[0]
https://github.com/CCC-Attestation/attested-tls-poc/pull/58#discussion_r3580301451

[1]
https://github.com/CCC-Attestation/attested-tls-poc/pull/58#discussion_r3580393272